Carnets Geol. 16 (5) 

Click here to close the window!

Contents

[I. Introduction] [II. Phylogeny] [III. Systematic paleontology]
[IV. Phylogenetic relationships ...] [V. Stratigraphical and paleogeographical distribution] [VI. Conclusions] [Bibliographic references] [Plates] and ... [Appendix]


Revision of the Early Cretaceous genera Heminautilus Spath, 1927,
and Josanautilus Martínez & Grauges, 2006
(Nautilida, Cenoceratidae)

Cyril Baudouin

16, rue Frédéric Mistral, 26200 Montélimar (France)

Centre d'Études Méditerranéennes, 04170 St-André les Alpes (France)

Gérard Delanoy

Département des Sciences de la Terre, Université de Nice-Sophia-Antipolis, Faculté des Sciences, 28 avenue Valrose, 06108 Nice Cedex 2 (France)

Centre d'Études Méditerranéennes, 04170 St-André les Alpes (France)

Josep Anton Moreno-Bedmar

Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, 04510 México, D.F. (Mexico)

Antoine Pictet

Institute of Earth Sciences, Bâtiment Géopolis, 1015 Lausanne (Suisse)

Jean Vermeulen

Grand rue, 04330 Barrême (France)

Gabriel Conte (†)

"Lou Seren", 04300 Forcalquier (France)

Roland Gonnet

Chemin de Dardène, La Barthelasse, 84000 Avignon (France)
Centre d'Études Méditerranéennes, 04170 St-André les Alpes (France)

Patrick Boselli

57 bis, avenue des Patriotes, 26300 Bourg-de-Péage (France)

Centre d'Études Méditerranéennes, 04170 St-André les Alpes (France)

Marc Boselli

57 bis, avenue des Patriotes, 26300 Bourg-de-Péage (France)
Centre d'Études Méditerranéennes, 04170 St-André les Alpes (France)

Published online in final form (pdf) on April 14, 2016
[Editor: Bruno Granier; language editor: Stephen Carey]

Click here to download the PDF version!

Abstract

In spite of recent interest, the various species belonging to the genera Heminautilus Spath, 1927, and Josanautilus Martínez & Grauges, 2006, have never been the object of a general revision. More than 160 specimens belonging to various species of these two genera were studied, with the aim of identifying the specific characteristics and the stratigraphical and paleogeographical distribution of the various species which compose them, as well as to propose a phylogeny for the group. This study confirms the non-synonymy of Heminautilus saxbii (Morris, 1848) and H. lallierianus (Orbigny, 1841), establishes that H. tejeriensis Martínez & Grauges, 2006, and H. verneuilli (Vilanova, 1870) represent junior synonyms of H. saxbii (Morris) and suggests the creation of the species H. ? japonicus sp. nov. The origin of the genus Heminautilus Spath from Pseudocenoceras Spath, 1927, proposed by Tintant, and the origin of Josanautilus Martínez & Grauges from Heminautilus Spath are both confirmed.

Key-words

Nautiloidea; Cenoceratidae; Heminautilus; Josanautilus; Early Cretaceous; Barremian; Aptian.

Citation

Baudouin C., Delanoy G., Moreno-Bedmar J.A., Pictet A., Vermeulen J., Conte G. , Gonnet R., Boselli P. & Boselli  M. (2016).- Revision of the Early Cretaceous genera Heminautilus Spath, 1927, and Josanautilus Martínez & Grauges, 2006 (Nautilida, Cenoceratidae).- Carnets Geol., Madrid, vol. 16, no. 5, p. 61-212.

Résumé

Révision des genres Heminautilus Spath, 1927, et Josanautilus Martínez & Grauges, 2006 (Nautilida, Cenoceratidae), du Crétacé inférieur.- Malgré des travaux récents, les différentes espèces appartenant aux genres Heminautilus Spath, 1927, et Josanautilus Martínez & Grauges, 2006, n'ont jamais fait l'objet d'une révision d'ensemble. Plus de 160 spécimens appartenant à différentes espèces de ces deux genres ont été étudiés dans le but de cerner les caractères spécifiques et la répartition stratigraphique et paléogéographique des différentes espèces qui les composent, ainsi que de proposer un schéma phylogénétique de ce groupe. Cette étude a permis en particulier de confirmer la non-synonymie d'Heminautilus saxbii (Morris, 1848) et d'H. lallierianus (Orbigny, 1841), d'établir qu'H. tejeriensis Martínez & Grauges, 2006, et H. verneuilli (Vilanova, 1870) représentent des synonymes juniors d'H. saxbii (Morris), et de créer l'espèce H. ? japonicus sp. nov. L'origine du genre Heminautilus Spath chez Pseudocenoceras Spath, 1927, proposée par Tintant, a pu être confortée et l'origine de Josanautilus Martínez & Grauges chez Heminautilus Spath a également pu être confirmée.

Mots-clefs

Nautiloidea ; Cenoceratidae ; Heminautilus ; Josanautilus ; Crétacé inférieur ; Barrémien ; Aptien.


I. Introduction

The genus Heminautilus Spath, 1927, includes forms present in the Early Cretaceous (Early Barremian to Early Aptian), with very distinctive and easily recognizable morphology within the Nautiloidea Blainville, 1825. Its various representatives share a relatively compressed section, a strongly differentiated ventral region and a sinuous suture line, with a particularly well developed ventral lobe. For a long time the genus was poorly known and, in numerous works (F.-J. Pictet & Campiche, 1858; Douvillé, 1916; Dimitrova, 1967; Obata & Ogawa, 1976; Obata et al., 1984; Nikolov & Parashkevanov, 1995; Aly, 2006; Abu-Zied, 2008), its European and North African representatives were attributed without distinction to the species H. lallierianus (Orbigny, 1841) and H. saxbii (Morris, 1848), sometimes in spite of characteristics that clearly separate them from the type specimens. The recent works of Conte (1980, 1985, 1989, 2007, 2010), Martínez & Grauges (2006) and Delanoy et al. (2012) contributed to a better knowledge of the genus, in particular with the creation of the species H. sanctaecrucis Conte, 1980, H. tejeriensis Martínez & Grauges, 2006, and H. boselliorum Delanoy et al., 2012. Furthermore, Martínez & Grauges recently erected the monospecific genus Josanautilus Martínez & Grauges, 2006, for the species Nautilus lacerdae Vilanova, 1870, phylogenetically very close to the genus Heminautilus Spath. However, no global revision of these two genera has been undertaken until now. The object of the present work is to clarify the diagnostic characteristics of the various species and to summarise their geographical and stratigraphical distribution as well as the phyletic links between them.

We also look at the possible synonymy between the species H. lallierianus (Orbigny, 1841) and H. saxbii (Morris, 1848), that has been suggested by numerous authors (Orbigny, 1850; F.-J. Pictet & Campiche, 1858; Douvillé, 1916; Scott, 1943).

II. Phylogeny

1. The systematic position and origin of the genus Heminautilus Spath, 1927

The classification of Spath

Spath (1927) is the first author to propose a classification of Nautiloidea, based purely on morphological criteria. Thus he classifies the genus Heminautilus Spath, 1927, in the Family Paracenoceratidae Spath, 1927, which gathers all the forms with a differentiated ventral region and a suture line containing a well developed ventral lobe. However, Spath (1927, p. 25) himself recognizes the polyphyletic character of this family. The works of Tintant (Tintant & Kabamba, 1983; Tintant, 1993) will later show that this classification does not actually take into account phyletic data and that numerous identical morphological characteristics appear in an iterative way in various lineages. The classification of Spath was used, however, by Dzik (1984, p. 181) who presented a phylogenetic outline of the Family Paracenoceratidae Spath.

The classification of Kummel

In 1956, Kummel briefly returns to the classification proposed by Spath (1927). He keeps most of the families proposed by the latter but reducing them to the rank of subfamily. However, he moves the genus Heminautilus Spath, 1927, into the Subfamily Cymatoceratinae Spath, 1927. Indeed, he notes (p. 435) that the suture line of the genus Heminautilus Spath is more sinuous than that of the other representatives of the Paracenoceratidae Spath, 1927, and that some specimens of Heminautilus Spath [specimens attributed to Nautilus lallieri Orbigny, 1841, by Douvillé, 1916, Pl. 17, figs. 2-4, 6; Heminautilus rangei (Hoppe, 1922)] possess sinuous ribbing close to that observed on the genus Cymatoceras Hyatt, 1884, while other representatives of the Paracenoceratidae Spath show no ribbing.

However, in a recent work, Chirat & Bucher (2006, p. 62) showed that the structure of the shell as well as the ribbing observed on the specimens of Heminautilus Spath illustrated by Douvillé (1916, Pl. 17, figs. 2-4, 6) are very different from that observed on Cymatoceras Hyatt, and that consequently there is no direct phyletic link between these two genera.

The works of Tintant

In various papers (Tintant & Kabamba, 1983, 1985; Tintant, 1980, 1989, 1993), Tintant established a new classification based on phyletic data rather than strictly morphological. Thus, he established (1993) that characteristics such as the presence of ribbing, a flat or concave ventral region, or even a sinuous suture line, appear in an iterative way in very different lineages. These features are interpreted as an adaptive answer to a particular environment and are not systematically considered as the consequence of a phyletic link. To establish his new classification, Tintant used the usual specific characters (ornamentation, suture line, section and ventral region shape, position of the siphon) by interpreting them either as the indication of a phyletic link or as an iterative homeomorphy, in particular for stratigraphically distant species. For Tintant & Kabamba (1983), the genus Heminautilus Spath, 1927, derives from the genus Pseudocenoceras Spath, 1927, by the appearance of a sinuous suture line and a concave ventral region. However, this last genus, in the conception of Kummel (1956), seems polyphyletic: it contains various species distributed from the Berriasian to the Maastrichtian. In the Early Cretaceous, the only known species are Pseudocenoceras berriasensis (F.-J. Pictet, 1867) from the Berriasian of southeast France, Pseudocenoceras campichei (Karakasch, 1907) from the Hauterivian? of Crimea and Pseudocenoceras picteti (Karakasch, 1907) from the Early Barremian? of Crimea. No representative of the genus Pseudocenoceras Spath seems to be known in the Valanginian, Aptian and Albian; in the Cenomanian the genus is again present, particularly in the form of its type species P. largilliertianus (Orbigny, 1841). It seems clear that for Tintant the genus Heminautilus Spath derives from the group formed by the Early Cretaceous taxa P. berriasensis (F.-J. Pictet), P. campichei (Karakasch) and P. picteti (Karakasch), even if the phyletic links amongst these three species remain to be specified.

The systematic position adopted in this work

By considering the morphological characteristics and the stratigraphical position of the various representatives of the genus Heminautilus Spath, 1927, another hypothesis on the phyletic position of this genus can be envisaged. Indeed, the genus Xenocheilus Shimansky & Erlanger, 1955, present from the Berriasian to the Hauterivian, even to the Early Barremian, shows morphological characteristics close to Heminautilus Spath. According to Shimansky (1975), followed by Tintant & Kabamba (1983), this genus belongs to the Family Pseudonautilidae Shimansky & Erlanger, 1955, close to the genera Pseudonautilus Meek, 1876, and Aulaconautilus Spath, 1927, which would indicate that all three derive from the Jurassic genus Pseudaganides Spath, 1927.

The genus Xenocheilus Shimansky & Erlanger, and in particular the taxon Xenocheilus ulixis Shimansky & Erlanger, 1955, from the Hauterivien of Crimea (see Pl. I , fig. 1), have a very involute coiling with a flat or slightly concave ventral region, and a suture line with a deep lateral lobe and a well indented ventral lobe. As observed by Dzik (1984, p. 180-181), it would be possible to postulate here the origin of the first representatives of the genus Heminautilus Spath, which could derive from Xenocheilus ulixis Shimansky & Erlanger by a slight modification of the sutural line (lateral lobe shallower, wider and round in Heminautilus Spath) and a reduction of the width of the ventral region. However, the position of the siphuncle is a major obstacle to the hypothesis of a direct ancestor-descendant relationship between Xenocheilus and Heminautilus, because in Heminautilus Spath the siphuncle is always situated in the lower half of the section while it is close to the ventral region in Xenocheilus Shimansky & Erlanger and in all the Pseudonautilidae Shimansky & Erlanger. These ornamental and sutural similarities were previously noted by Shimansky (1975) who considered them due to morphological convergence.

The systematic position adopted by Tintant (Tintant & Kabamba, 1983; Tintant, 1993), who considers that the genus Heminautilus Spath, 1927, comes from Pseudocenoceras Spath, 1927, corresponds best with the current data, and consequently the genus Heminautilus Spath is here placed within the Family Cenoceratidae Tintant & Kabamba, 1983. The main characteristics of the genus Pseudocenoceras Spath, 1927, are a wide and flattened ventral region, a subrectangular section, a slightly sinuous suture line and the siphuncle in a subcentral position, closer to the dorsal face than to the ventral region. In the hypothesis of Tintant, the genus Heminautilus Spath would thus derive from Pseudocenoceras Spath by the appearance of a sinuous suture line developing a strong lateral lobe, and of a ventral region with angular edges, as well as by a slight lower position of the siphuncle on the section. From this perspective, the taxon Pseudocenoceras campichei (Karakasch, 1907), from the Hauterivian? of Crimea (Pl. I , fig. 2), seems to be the best candidate for the origin of the genus Heminautilus Spath, both morphologically and stratigraphically. However, the current data on these two genera and, in particular, on possible specimens from the Late Hauterivian - Early Barremian remain too fragmentary to provide confirmation, and the hypothesis of Tintant needs to be supported by a more plentiful material.

2. The systematic position and origin of the genus Josanautilus Martínez & Grauges, 2006

The monospecific genus Josanautilus Martínez & Grauges, 2006, based on its type species Nautilus lacerdae Vilanova, 1870, is a taxon known only from the Early Aptian of Spain and southeast France. Its ornamental and sutural characteristics, as well as its stratigraphical position, show that this species is very close to the genus Heminautilus Spath, 1927, as noted by Shimansky (1975, p. 124) and Martínez & Grauges (2006, p. 17). Furthermore, both genera seem to have similar environmental requirements and are generally present only in the outer platform domain; the genus Heminautilus Spath is generally associated with Josanautilus Martínez & Grauges in deposits where the latter is present. They have in common a similar sutural line, a siphuncle placed in the lower half of the section, a flat ventral region, a trapezoidal section and very involute coiling. The ribbing on the flanks of the body chamber in Josanautilus Martínez & Grauges is also similar to that observable on some ornamented forms of the genus Heminautilus Spath. The essential difference between the genera is the presence in Josanautilus Martínez & Grauges of a wider and slightly convex ventral region, with a strong central keel surrounded by one or two longitudinal ribs. These characteristics show clearly that Josanautilus Martínez & Grauges comes from the genus Heminautilus Spath, probably by way of the taxon Heminautilus sanctaecrucis Conte, 1980, whose ventral region shows a median keel.

On the other hand, Josanautilus lacerdae (Vilanova, 1870) shows morphological similarities with the Berriasian species Aulaconautilus sexcarinatus (F.-J. Pictet, 1867), the cast of whose holotype is shown here (Pl. II , fig. 1). Indeed, this last taxon is characterized by a sinuous suture line, as well as by the presence of six or eight longitudinal ribs on a wide and flattened ventral region. However Aulaconautilus sexcarinatus (F.-J. Pictet) differs from Josanautilus lacerdae (Vilanova) by clear differences in the suture line which shows a far less developed lateral saddle and a narrower and less round lateral lobe. The ornamentation of the ventral region of J. lacerdae (Vilanova) also presents only superficial similarities to that of A. sexcarinatus (F.-J. Pictet) and can be distinguished easily by the presence of a median keel and the absence of longitudinal ribs on the phragmocone. Furthermore, no ribbing is visible on the flanks in A. sexcarinatus (F.-J. Pictet); the section of the latter is clearly narrower, and subrectangular instead of trapezoidal as in J. lacerdae (Vilanova); and the whorls' height increases more slowly than in J. lacerdae (Vilanova). All of these characteristics, associated with a very different stratigraphical position [Berriasian for A. sexcarinatus (F.-J. Pictet) and Early Aptian for J. lacerdae (Vilanova)], show that the similarities between these taxa represent only homeomorphic characteristics and not the consequence of a phyletic link, as noted by Martínez & Grauges (2006, p. 17).

III. Systematic paleontology

Methodology and conventions: the measurements of height (H), thickness of the whorls (E) and width of the ventral region (M) were made at various diameters (D) (Fig. 1 ). The measurements of the variation of the lateral lobe of the suture line were made according to the method of Marchand & Tintant (1971): L indicates the width of the lateral lobe and P indicates its depth (Fig. 1 ). The measurements indicated in bold and italic type were made from photos and are thus subject to some uncertainty (Tables 2-14). To simplify the text, repositories of the studied or quoted specimens are abbreviated (Table 1). The biozonation of the Early Cretaceous used here (Fig. 2 ) is the one developed by the IUGS Lower Cretaceous Ammonite Working Group (Reboulet et al., 2011, 2014), for the North-Tethyan Domain, with the exception of the Imerites giraudi Zone which is split into three subzones at the top of the Barremian (Bert et al., 2008, and Reboulet et al., 2011). It is correlated for the end of the Early Aptian with the biozonation developed by Moreno-Bedmar et al. (2015) for Mexico and southern North America and the one developed by Etayo-Serna (1979) for Colombia.

Fig. 1
Click on thumbnail to enlarge the image.

Figure 1: Explanatory scheme for the measurements made on the studied specimens.

Fig. 2
Click on thumbnail to enlarge the image.

Figure 2: Biozonation of the Barremian and Aptian (Early Cretaceous) used in this work.

Table 1: List of abbreviations used in the text.

AMNH American Museum of Natural History, New York, United States
BEG Bureau of Economic Geology, Austin, Texas, United States
BMNH British Museum of National History, England
EM École des Mines, Claude Bernard University, Lyon, France
FSM Faculté des Sciences of Marseille, France
GK Kyushu University, Japan
GMMU Geological Museum of Mansoura University, Egypt
GSUB Geosciences Collection of the University of Bremen, Germany
HNHM Hungarian Natural history Museum
IGM Instituto de Geología, Universidad Nacional Autónoma de México
MB Natural History Museum of Bâle, Switzerland
MCGL Muséum Géologique Cantonal of Lausanne, Switzerland
MGB Museu de Geologia de Barcelona, Spain
MGNR Museo Geológico Nacional J. Royo y Gómez, Bogotá, Colombia
MHNA Natural History Museum of Auxerre, France
MHNG Natural History Museum of Geneva, Switzerland
MHNN Natural History Museum of Neuchâtel, Switzerland
MNCN Museo Nacional de Ciencias Naturales, Madrid, Spain
MNHN Muséum National d’Histoire Naturelle of Paris, France
MPL Museo Paleontológico Laguna, Torreón, Coahuila State, Mexico
MPUC Museum of Paleontology, California University, United States
MPUS Museum of Paleontology, Sofia University, Bulgaria
MV Museum of Valltorta, Spain
NMNS National Science Museum, Tokyo, Japan
PNRL Parc Naturel Régional du Lubéron, France
PUAB Universitat Autònoma de Barcelona, Spain
UNCB Colecciones Paleontológicas, Departamento de Geociencias, Universidad Nacional de Colombia, Bogotá
UPMC Pierre et Marie Curie University, Paris, France
USNM United States National Museum, Washington, United States

Order Nautilida Agassiz, 1847

Superfamily Nautiloidea Blainville, 1825

Family Cenoceratidae Tintant & Kabamba, 1983

Genus Heminautilus Spath, 1927

(= Vorticoceras Scott, 1940; ? Platynautilus Yabe & Ozaki, 1953)

Type species: Nautilus saxbii Morris, 1848 [by original designation of Spath (1927, p. 22)].

Discussion: the genus Vorticoceras Scott, 1940, is a synonym of Heminautilus Spath, 1927, as established previously Scott (1943) and Kummel (1956). The genus Platynautilus Yabe & Ozaki, 1953, is probably also a synonym of Heminautilus Spath (see discussion in section V). The genus Heminautilus Spath includes the species H. boselliorum Delanoy et al., 2012, H. rangei (Hoppe, 1922), H. sanctaecrucis Conte, 1980, H. saxbii (Morris, 1848) [= H. verneuilli (Vilanova, 1870); H. tejeriensis Martínez & Grauges, 2006], H. lallierianus (Orbigny, 1841), H. etheringtoni Durham, 1946, H. stantoni (Scott, 1940), H. ? japonicus sp. nov. and H. ? tyosiensis (Yabe & Osaki, 1953); its known stratigraphical distribution extends from the Early Barremian, Kotetishvilia nicklesi Zone, to the top of the Early Aptian, Dufrenoyia furcata Zone. It is present in Europe (Bulgaria, England, France, Hungary, Spain and Switzerland), North Africa (Egypt and Tunisia), Ethiopia, Japan, North America (USA [Arkansas], Mexico [Puebla and Durango states]), and northern South America (Colombia and Venezuela).

The taxon Heminautilus akatsui Matsumoto, 1980 (in Matsumoto et al., 1980), from the Early Albian of Japan, shows an unusual stratigraphical position and ornamental and sutural characteristics very different from those classically present in the genus Heminautilus Spath and in particular in its type species; it certainly belongs to a different genus. Its holotype is featured in this work (Pl. II , fig. 2).

Heminautilus boselliorum Delanoy et al., 2012

Pl. II , fig. 3; Pl. III , figs. 1-3; Pl. IV , figs. 1-3; 
Pl. V
, figs. 1-2; Pl. VI , figs. 1-2; Pl. VII , figs. 1-2, 4; 
Pl. VIII
, figs. 1-3; Pl. IX , figs. 1-3

?

1975

Heminautilus sp. - Shimansky, Pl. 27, fig. 4.

pars

1995

Heminautilus saxbii (Morris, 1848) - Nikolov & Parashkevanov, p. 65: no. K1 1693, K1 1694, non no. K1 6005, Pl. 5, fig. 1, 1a (= ? H. sanctaecrucis Conte, 1980).

2002

Heminautilus aff. saxbii (Morris, 1848) - Vermeulen, p. 37.

2012

Heminautilus boselliorum sp. nov. - Delanoy et al., p. 157, Pl. 1, fig. 1; Pl. 2, figs. 1-2; Pl. 3, figs. 1-2; Pl. 4, fig. 2; Pl. 8, fig. 2; Pl. 9, fig. 2; Pl. 11, fig. 2; Pl. 12, fig. 1.

2013

Heminautilus sp. - Főzy & Szente, p. 183.

Material studied (N = 13): specimens no. Mej01a, Mej02, Mej03, Mej11, coll. Baudouin, no. RG2000, RG2001, RG2002a, b, coll. Gonnet, no. LUS01, LUS02, coll. Boselli, no. MNHN.F.A52065, Early Barremian, Nicklesia pulchella Zone, La Lèque, Lussan (Gard, France); specimen no. MHNG GEPI 15935, Nicklesia pulchella Zone?, Escragnolles (Alpes-Maritimes, France); specimen no. 415950, coll. Vermeulen, upper part of the Kotetishvilia nicklesi Zone, section no. 833, Comps-sur-Artuby (Var).

Type: the holotype (by original designation) is the specimen no. Mej01a, coll. Baudouin, presented by Delanoy et al. (2012, Pl. 1, fig. 1a-c); a cast is deposited in the paleontology collections of the Muséum National d'Histoire Naturelle of Paris with the no. MNHN.F.A52064.

Geographical distribution: the species is known from France (departments of the Gard, the Var and the Alpes-Maritimes), Bulgaria and Hungary.

Stratigraphical distribution: Heminautilus boselliorum Delanoy et al., 2012, is present in the Early Barremian, upper part of the Kotetishvilia nicklesi Zone and Nicklesia pulchella Zone of southeast France, and in the lower part of the Kotetishvilia compressissima Zone in Hungary (specimen no. M 2002.554, coll. HNHM, Pl. IX , fig. 2, bed 126 of the Bersek quarry, Gerecse Mountains; Főzy & Janssen, 2009). The Bulgarian specimens (coll. MPUS) no. K1 1693 (Pl. VIII , fig. 1; Pl. IX , fig. 1) and K1 1694 (Pl. VIII , fig. 2) (studied by Nikolov & Parashkevanov, 1995, p. 65) come from the Early Barremian without more precision. The specimen no. MHNG GEPI 15935 (Pl. VII , fig. 1; Pl. IX , fig. 3) from Escragnolles (Alpes-Maritimes, France) is assumed to come from the Nicklesia pulchella Zone based upon the character of its matrix.

Dimensions (in mm): see Table 2.

Table 2: Measurements of Heminautilus boselliorum Delanoy et al., 2012.

D H E H/D E/D E/H M M/D M/H P L P/L L/H
Holotype no. Mej01a 156 89.4 56.3 0.57 0.36 0.63 15 0.1 0.17 - - - -
141.9 85.5 48.7 0.6 0.34 0.57 14 0.1 0.16 - - - -
122.2 73.3 36.5 0.6 0.3 0.5 12.3 0.1 0.17 16 56 0.29 0.76
113.1 67 33.2 0.59 0.29 0.5 10.7 0.09 0.16 16 51 0.31 0.76
- 50 26.1 - - 0.52 8.6 - 0.17 14 35 0.4 0.7
- 43.5 24.1 - - 0.55 8.5 - 0.2 9.4 33 0.28 0.76
no. Mej02 139.3 74.4 44.5 0.53 0.32 0.6 12.4 0.09 0.17 - - - -
- 54 - - - - 8 - 0.15 12 41 0.29 0.76
no. Mej03 133.5 c80 34 0.6 0.25 0.43 12.5 0.09 0.16 - - - -
102.8 c58 29.5 0.56 0.29 0.51 8.7 0.08 0.15 16.3 47 0.35 0.81
95.2 53.8 29.3 0.57 0.31 0.54 8.2 0.09 0.15 15.5 45 0.34 0.84
no. Mej11 - 89.7 - - - - 16.3 - 0.18 - - - -
- 70.1 37.9 - - 0.54 13.1 - 0.19 11.1 58.3 0.19 0.83
no. RG2000 131.3 78.2 - 0.6 - - 12.4 0.09 0.16 - - - -
112.3 71.2 - 0.63 - - 11.3 0.1 0.16 14.9 52.2 0.29 0.73
98.2 61.9 - 0.63 - - 8.7 0.09 0.14 16.6 48.2 0.34 0.78
no. RG2001 148.8 87.4 46.6 0.59 0.31 0.53 - - - - - - -
134.3 82.1 c32.6 0.61 0.24 0.4 c10.2 0.08 0.12 18.8 59.6 0.32 0.73
- 52.4 c22.8 - - 0.44 c4.5 - 0.09 9.4 40.4 0.23 0.77
no. RG2002a 155.8 92.8 55.5 0.6 0.36 0.6 14.2 0.09 0.15 - - - -
- 71 40.9 - - 0.58 12.3 - 0.17 19.2 59.7 0.32 0.84
- 63.3 33.2 - - 0.52 11 - 0.17 18.2 51.4 0.35 0.81
no. RG2002b 153 82.2 c54.7 0.54 0.36 0.67 21.1 0.14 0.26 - - - -
132 82.1 c41.2 0.62 0.31 0.5 14.2 0.11 0.17 15.8 60.7 0.26 0.74
no. MNHN.F.A52065 65.7 c41 24.5 0.62 0.37 0.6 5 0.08 0.12 - - - -
no. LUS01 148.7 83.8 45.9 0.56 0.31 0.55 18.5 0.12 0.22 - - - -
108.9 69 30.4 0.63 0.28 0.44 9.7 0.09 0.14 11.7 52.8 0.22 0.77
92 58.9 - 0.64 - - 7.6 0.08 0.13 11.8 44.7 0.26 0.76
no. LUS02 68.3 41.2 21.7 0.6 0.32 0.53 7.6 0.11 0.18 9.1 30.1 0.3 0.73
- 26.5 16 - - 0.6 4.4 - 0.17 5.1 20.5 0.25 0.77
no. MHNG GEPI 15935 128 81 - 0.63 - - 15 0.12 0.19 - - - -
- 78 - - - - 13.5 - 0.17 15 54 0.28 0.69
- 65 - - - - 9 - 0.14 14 46.5 0.3 0.72
no. 415950 83.5 47.3 26.1 0.57 0.31 0.55 7.4 0.09 0.16 - - - -
74.5 43.5 22.1 0.58 0.3 0.51 6.5 0.09 0.15 11.3 34.1 0.33 0.78
- 28.6 19.6 - - 0.69 5.3 - 0.19 8.8 22.6 0.39 0.79
no. K1 1693 - 85.6 43.4 - - 0.51 13.5 - 0.16 - - - -
- 74.4 - - - - 11.5 - 0.15 14.9 54.9 0.27 0.74
- 54.1 - - - - - - - 13.3 43.3 0.31 0.8
no. K1 1694 - 30.4 17.9 - - 0.59 6.3 - 0.21 5.9 22.7 0.26 0.75
- 27.9 - - - - 5.2 - 0.19 6 20.8 0.29 0.75
- 23.3 - - - - - - - 5.5 18.7 0.29 0.8
no. M 2002.554 104.1 60.9 - 0.59 - - - - - 14.9 44.5 0.33 0.73
79.1 45.4 - 0.57 - - - - - 10.5 32.6 0.32 0.72

Description: the studied specimens show a compressed section (E/H between 0.40 and 0.69) and a very involute conch, with convex flanks, with maximum thickness situated approximately at the bottom third. Until D = 35 mm the ventral region is slightly convex, becoming then clearly flat, with two angular edges. On the body chamber, the angular edges heighten as weak keels and give a clearly concave shape to the ventral region. In well preserved specimens, we also observe the presence of a very slight keel, wide and rounded, especially visible at the end of the phragmocone and the beginning of the body chamber.

Virtually none of the shells displays ornamentation. However, in the adult specimens, some weak rursiradiate ribs appear at the end of the body chamber, in the upper third of the flanks. Specimen no. MHNG GEPI 15935, from the Nicklesia pulchella Zone? of Escragnolles (Alpes-Maritimes), shows similar ornamentation which appears earlier on the body chamber. Its characteristics and stratigraphical position permits its assignment to H. boselliorum Delanoy et al.

The suture line (Fig. 3 ) contains a very wide, relatively shallow lateral lobe (P/L ranges between 0.19 and 0.40), a reduced umbilical saddle and an indented ventral lobe. The siphuncle, highly visible on specimens no. Mej11 (Pl. III , fig. 3c) and no. LUS02 (Pl. IV , fig. 3b) is located very low, near the dorsal edge of the section.

Fig. 3
Click on thumbnail to enlarge the image.

Figure 3: Heminautilus boselliorum Delanoy et al., 2012. Suture line of specimens no. Mej01, left side (a), MHNG GEPI 15935, right side (b), RG2001, left side (c) and Mej02, right side (d).

Variability: the sample (N = 13) studied here consists of sufficient well stratigraphically located specimens to allow a statistical analysis. The sample constitutes a quite homogeneous group, permitting us to estimate the intraspecific variability. The variability is minor and involves only the wideness of the conch and the morphology of the ventral region. The thickness of the shell varies from thin, in which the ratio E/H is between 0.40 and 0.50, to clearly thicker in which E/H can exceed 0.60. The width of the ventral region is directly correlated to the thickness of the shell: in the thin forms M/H is between 0.10 and 0.15, while in thick morphs this ratio can exceed 0.25. Independently, the shape of the ventral region varies on the phragmocone from flat to slightly concave, with the presence or absence of a very slight central keel, generally towards the end of the phragmocone or the beginning of the body chamber. To a lesser extent, we also observe a certain variability in the the suture line, with a more or less deep lateral lobe, whose ratio P/L can vary from 0.19 to 0.40. Rather significant variations in its depth are sometimes observed in the same specimen at various diameters, without an obvious link to an ontogenic stage.

Discussion and comparisons: Heminautilus boselliorum Delanoy et al., 2012, is a species very close to H. saxbii (Morris, 1848). However, it can be distinguished from H. saxbii (Morris) by a slightly less developed lateral lobe, with the average ratio P/L of 0.30 in H. boselliorum Delanoy et al., and of 0.35 in H. saxbii (Morris). In reference to the ornamentation and form of the shell, it can be distinguished by the presence of a very slight keel on the ventral region of the best preserved specimens of H. boselliorum Delanoy et al. and a slightly differing section, as well as by ribbing which appears earlier on the body chamber of H. saxbii (Morris). H. boselliorum Delanoy et al. also occupies a stratigraphical position very different from that of H. saxbii (Morris, 1848); this last taxon is known only in the Early Aptian, Deshayesites forbesi Zone.

H. boselliorum Delanoy et al. is also similar to H. sanctaecrucis Conte, 1980, from the latest Barremian - Early Aptian, Deshayesites forbesi Zone. H. sanctaecrucis Conte can be easily distinguished by the presence of a strong median keel on the ventral region, as well as by shoulders lining the ventral region which are clearly stronger on the body chamber of adult specimens.

Finally, H. boselliorum Delanoy et al. can be distinguished readily from H. lallierianus (Orbigny, 1841) from the Early Aptian by its far less developed lateral lobe [P/L between 0.35 and 0.50 in H. lallierianus (Orbigny)], its far less concave ventral region and its ontogenetically much later ribbing on the body chamber.

Heminautilus rangei (Hoppe, 1922)

Pl. VII , fig. 3; Pl. IX , figs. 4-5; 
Pl. X
, figs. 1-3; Pl. XI , figs. 1-2

pars

1916

Nautilus lallieri Orbigny, 1841 - Douvillé, p. 129, Pl. 17, figs. 2-4, 6, non fig. 5 [= H. saxbii (Morris, 1848)].

1922

Nautilus rangeï nov. sp. - Hoppe, p. 144, Pl. 4, figs. 2-3.

2008

Heminautilus lallierianus (Orbigny, 1841) - Abu-Zied, fig. 3, A-C.

Material studied (N = 4): specimens no. EM696, EM697, EM698, EM699, Late Barremian?, Bir Lagama (north Sinai, Egypt).

Type: Hoppe (1922) figured two specimens (Pl. 4, figs. 2-3) from "Ledschime" (north Sinai, Egypt; Fig. 4 ), without nomination of a holotype; the illustration of Hoppe (1922) is reproduced here on Pl. XI , figs. 1-2. These two specimens belonged to the Range collection, stored in the Geologisch-paläontologischen Institut der Universität Leipzig (Germany), but could not be found and can be considered as lost. The original figures of Hoppe (1922, reproduced here Pl. XI , figs. 1-2) prevent the development of a complete picture of the species. In particular, the shape of the ventral region is difficult to construe and gives the impression of being strongly concave. The specimens no. EM696, EM697, EM698 and EM699, as well as specimen no. TK25/15 (Pl. X , fig. 3) illustrated by Abu-Zied (2008), show that the ventral region of this species is not strongly concave. Furthermore, in the original depictions the specimen in lateral view is fragmentary, so that only the ornamentation of the upper part of the flanks is visible. In the absence of specimens attributable to this species in the Range collection, we erect as a neotype the specimen no. EM699 (Pl. X , fig. 1), illustrated by Douvillé (1916, Pl. 17, fig. 6a-b) and stored in the collection of the École des Mines (Université Claude Bernard, Lyon, France). It comes from Bir Lagama, a locality very close to that of the type specimens displayed in Hoppe (1922) (Fig. 4 ), and is probably from the Late Barremian, Gerhardtia sartousiana or Imerites giraudi zones (cf. section "stratigraphical distribution").

Fig. 4
Click on thumbnail to enlarge the image.

Figure 4: Geological map of the north Sinai (Egypt). Modified from Abu-Zied (2008).

By means of this neotype, completed by the paratypes no. EM696, EM697 and EM698 showing the various ontogenetic stages of the species, we can define the specific characteristics of H. rangei Hoppe, 1922, more accurately than using the original depiction of Hoppe, 1922.

Geographical distribution: the species is known only in the north of the Sinai (Egypt). All the known specimens come from a very restricted area (Fig. 4 ): those presented by Hoppe (1922) come from "Ledschime", a location corresponding approximately (Range, 1920, Pl. 8) to the section of El Tourkumanyia described by Abu-Zied (2008), the source of the specimen no. TK25/15 (coll. GMMU); the neotype no. EM699 and the three paratypes no. EM696, EM697 and EM698 come from Bir Lagama, situated slightly further west in the same massif.

Stratigraphical distribution: both specimens shown in Hoppe (1922) were dated, according to him, from the Vraconian (= latest Albian). However, the presence in the same formation ("Ledschime-Horizont") of representatives of the genus Peudohaploceras Hyatt, 1900, close to P. douvillei (Fallot, 1920) (= Puzosia kossmati sp. nov. in Hoppe, 1922, p. 140, Pl. 3, fig. 10) indicates a very likely Late Barremian age. The specimen no. TK25/15 (Pl. X , fig. 3) illustrated by Abu-Zied (2008) comes from the Late Barremian, Subpulchellia oehlerti Zone [= Mogharaeceras priscum (Douvillé, 1916)]. According to Bulot et al. (2011), Mogharaeceras priscum (Douvillé) is a Late Barremian species, probably present in an interval included in Gerhardtia sartousiana to Imerites giraudi zones. Abu-Zied (2008) also indicates, without figures, the presence of Heminautilus lallierianus (Orbigny, 1841) [= Heminautilus rangei (Hoppe, 1922) or Heminautilus saxbii (Morris, 1848) ?] in the Early Aptian. Specimens depicted by Douvillé are attributed by him to the Aptian without more precision. However, compared with the specimen shown by Abu-Zied (2008), which presents exactly the same ornamental and morphological characteristics, such a stratigraphical position seems doubtful and these specimens are more likely from the Late Barremian. These specimens were also reallocated to the Barremian by Mahmoud (1955, p. 12). Thus Heminautilus rangei (Hoppe, 1922) is clearly present in the Late Barremian, in the Gerhardtia sartousiana Zone or Imerites giraudi Zone; its supposed presence in the Early Aptian is unproven and might stem from the confusion with another species collected in higher levels as attested by the presence of Heminautilus saxbii (Morris, 1848) among the material collected by Douvillé (1916).

Dimensions (in mm): see Table 3.

Table 3: Measurements of Heminautilus rangei (Hoppe, 1922).

D H E H/D E/D E/H M M/D M/H P L P/L L/H
Type specimen (Hoppe, 1922) 125 80 50 0.64 0.4 0.63 - - - - - - -
Neotype no. EM699 135.8 87.8 - 0.65 - - 16.1 0.12 0.18 - - - -
94.1 55.5 38.4 0.59 0.41 0.69 10.4 0.11 0.19 - - - -
no. EM698 72.5 43.6 28.7 0.6 0.4 0.66 6.3 0.09 0.14 9.6 35 0.27 0.8
52.8 34.8 22.5 0.66 0.43 0.65 5.3 0.1 0.15 7.5 28 0.27 0.8
no. EM697 59 38 24.6 0.64 0.42 0.65 5.6 0.09 0.15 - - - -
46.3 28.8 18.5 0.62 0.4 0.64 4.7 0.1 0.16 6.1 23.5 0.26 0.82
32.3 19.8 13.9 0.61 0.43 0.7 3.5 0.11 0.18 4.1 16.4 0.25 0.83
no. EM696 35 24.7 15.6 0.71 0.45 0.63 3.8 0.11 0.15 - - - -
no. TK25/15 (Abu-Zied, 2008) 125 74 41 0.59 0.33 0.55 12 0.1 0.16 - - - -

Description: the four specimens of the collection of the École des Mines, all illustrated by Douvillé (1916, Pl. 17) as Nautilus lallierianus Orbigny, 1841, provide precise knowledge about the ontogeny and the characteristics of this species. The neotype no. EM699, preserved with at least a part of its body chamber, probably represents the adult stage of the species.

With a diameter of up to about 20 mm, no ornamentation is visible with the exception of fine longitudinal striae on the flanks and the ventral region, visible on the shell of the paratype no. EM696 (Pl. IX, fig. 4). The section is oval, with rounded flanks and ventral region. Beyond this diameter, the section changes and becomes trapezoidal; flanks flatten and converge on the ventral region which very gradually becomes flat, with the appearance of a slight ventro-lateral shoulder. At the same time, the ribbing appears, consisting of broad ribs arising near the umbilical border and whose aboral edge follows a flat slope while the adoral edge is clearly more abrupt. Ribs are radial or slightly rursiradiate in the lower half of the flanks, becoming strongly rursiradiate beyond, and then fading approaching the ventral region. With growth, these ribs become broader and their point of appearance moves higher on the flanks. From approximately D = 70 mm, the ventral region is clearly flat (specimen no. EM698, Pl. IX , fig. 5; Pl. X , fig. 2). Finally, in the adult specimens (no. EM699, Pl. X , fig. 1; no. TK25/15, Pl. X , fig. 3), ribs appear slightly before the middle of flanks; they are very broad, flat, and barely separated by a narrow groove. They become irregular in their spacing, delineation and point of appearance on the flanks. The ventral region is lined by strong shoulders, giving to the ventral region a slightly to clearly concave shape (for example in the specimen illustrated by Hoppe (1922) Pl. 4, fig. 3; reproduced here Pl. XI , fig. 2). We also observe fine growth lines there forming a rounded chevron (specimen no. EM699, Pl. X , fig. 1b). Finally, at the end of the preserved part of the neotype no. EM699, a wide and slightly raised keel appears on the ventral region.

The suture line (Fig. 5 ), easily observable on specimens no. EM697 and no. EM698, shows a relatively undeveloped, rather narrow lateral saddle and a wide and shallow lateral lobe (P/L between 0.25 and 0.27). It crosses the ventral region straight, without forming a ventral lobe. The siphuncle, visible on specimens no. EM696 and no. EM697, is situated near the dorsal edge of the section.

Fig. 5
Click on thumbnail to enlarge the image.

Figure 5: Heminautilus rangei (Hoppe, 1922). Suture line of specimens no. EM698, right side (a-b), EM697, left side (c) and of the unregistered specimen, right side (d) figured by Hoppe (1922; Pl. 4, fig. 2).

Discussion and comparisons: the very characteristic ornamentation of Heminautilus rangei (Hoppe, 1922) differentiates it immediately from most of the other species of the genus Heminautilus Spath, 1927, where the ornamentation is absent or only present on the adoral part of the body chamber, with much narrower rounded ribs.

However, some characteristics of the shell of H. rangei (Hoppe), in particular the pattern of its suture line and the shape of its ventral region, indicate that this species is close to H. boselliorum Delanoy et al., 2012, and H. sanctaecrucis Conte, 1980. In H. sanctaecrucis Conte the median keel is consistently well developed in all specimens, whereas in H. rangei (Hoppe) it is observable in one specimen, the neotype no. EM699, but less developed than H. sanctaecrucis Conte.

H. rangei (Hoppe) is also similar to H. ? japonicus sp. nov., in particular its slightly concave ventral region, ornamented with fine growth lines, as well as its very similar stratigraphical position in the Late Barremian. However the suture line and the ribbing of H. ? japonicus sp. nov. are very different, which distinguishes it easily from H. rangei (Hoppe).

H. rangei (Hoppe) also shows some affinities with the Japanese species H. ? tyosiensis (Yabe & Osaki, 1953), because of its slightly concave ventral region lined with two strong shoulders, and the presence of comparable ribbing on a part of the phragmocone. However, H. ? tyosiensis (Yabe & Osaki) can be easily distinguished from H. rangei (Hoppe) by its much wider ventral region, its quickly fading ribbing and a different suture line, with a clearly deeper lateral lobe. H. ? tyosiensis (Yabe & Osaki) also occupies a very different stratigraphical and geographical position (= Dufrenoyia furcata Zone, Japan).

Heminautilus sanctaecrucis Conte, 1980

Pl. XI , figs. 3-5; Pl. XII , figs. 1-3; Pl. XIII , figs. 1-3; 
Pl. XIV
, figs. 1-2; Pl. XV , fig. 1; Pl. XVI , fig. 1

1858

Nautilus lallierianus Orbigny, 1841 - F.-J. Pictet & Campiche, p. 148, Pl. 19, fig. 6a-c.

1967

Xenocheilus lallierianus (Orbigny, 1841) - Dimitrova, p. 18, Pl. 4, fig. 1.

1980

Heminautilus sanctaecrucis sp. nov. - Conte, p. 137, Pl. 1. figs. 1-2, 4a.

1985

Heminautilus cf. sanctaecrucis Conte, 1980 - Conte, p. 30, Pl. 1, fig. 6.

1989

Heminautilus sanctaecrucis Conte, 1980 - Conte, p. 30, Figs. 5-7.

pars

1995

Heminautilus sanctaecrucis Conte, 1980 - Nikolov & Parashkevanov, p. 63, Pl. 1, fig. 1?; Pl. 2, fig. 1?; Pl. 3, figs. 1?, 2, 2a; Pl. 4, figs. 1, 1a, 2, 2a.

?

1995

Heminautilus saxbii (Morris, 1848) - Nikolov & Parashkevanov, p. 65, Pl. 5, fig. 1, 1a.

2009

Heminautilus sanctaecrucis Conte, 1980 - Lehmann et al., p. 904, Pl. 1, figs. 6.

2010

Heminautilus sanctaecrucis Conte, 1980 - Conte, p. 118, Figs. 6-7.

Material studied (N = 4): specimen no. MCGL 20747, Early Aptian, Deshayesites forbesi Zone, Sainte-Croix (Switzerland); specimens no. MHNG GEPI 15936, MHNN 26904, Early Aptian, Deshayesites forbesi Zone, La Presta, Val-de-Travers (Switzerland); specimen no. Bw599, coll. FSM, Late Barremian, Imerites giraudi Zone, Pseudocrioceras waagenoides Subzone, bed 78, Les Caniers, La Bédoule (Bouches du Rhône, France).

Type: the holotype (by original designation of Conte, 1980, p. 138) is the specimen no. MCGL 20747 illustrated by F.-J. Pictet & Campiche (1858) Pl. 19, fig. 6, as Nautilus lallierianus Orbigny, 1841. Stored in the Muséum Géologique Cantonal of Lausanne (Switzerland), it is depicted anew in this work Pl. XI , fig. 3.

Geographical distribution: the species is known in Switzerland, Bulgaria, southeast France and Tunisia.

Stratigraphical distribution: the holotype comes from the base of the "Marnes jaunes de la Vraconne" (F.-J. Pictet & Campiche, 1858) at Sainte-Croix (Switzerland), immediately above the Urgonian Limestone. The bottom third of these Jura marls corresponds to the Grünten Member defined in the Helvetic Domain, whose base is attributed to the Deshayesites forbesi Zone (A. Pictet et al., 2009, p. 492-493). The Bulgarian specimens (coll. MPUS) studied by Dimitrova (1967) and Nikolov & Parashkevanov (1995) are attributed to the Late Barremian (specimens no. K1 6001, K1 6002, K1 6003, K1 6004) and to the Early Aptian (specimen no. K1 1692) without more precision. In Tunisia the species is present in the Early Aptian, Deshayesites oglanlensis Zone (specimen no. GSUB C4035, Lehmann et al., 2009). In southeast France, the range of Heminautilus sanctaecrucis Conte, 1980, seems to be latest Barremian/earliest Aptian. The unregistered specimen of the Frasali collection (Pl. XV , fig. 1) comes from the Coustellet quarry (Vaucluse, France), situated in the units 3 and 4 of the series of the southwest region of the Vaucluse mountains and attributed to the Early Bedoulian by Masse (1976, p. 38-42). The specimen no. 131H (coll. Gesbert, Pl. XI, fig. 5; Pl. XII , fig. 1) comes from the col des Abeilles, Monieux (Vaucluse, France), and corresponds to the unit of the "Calcaires fins des Colombières" of the Nesque series, attributed to the latest Barremian/earliest Aptian by Masse (1976, p. 34-38). At La Bédoule (Bouches du Rhône, France) the species was collected at the top of the Late Barremian, Imerites giraudi Zone, Pseudocrioceras waagenoides Subzone (specimen no. Bw599, Pl. XII , fig. 2; Pl. XIII , fig. 1). Heminautilus sanctaecrucis Conte, 1980, is thus present from the Late Barremian, top of the Imerites giraudi Zone, to the Early Aptian, Deshayesites forbesi Zone.

Dimensions (in mm): see Table 4.

Table 4: Measurements of Heminautilus sanctaecrucis Conte, 1980.

D H E H/D E/D E/H M M/D M/H P L P/L L/H
Holotype no. MCGL 20747 96.3 55.4 34 0.58 0.35 0.61 9.8 0.1 0.18 - - - -
86.3 51 26.8 0.59 0.31 0.53 8.7 0.10 0.17 - - - -
69.2 41.3 21.9 0.6 0.32 0.53 7.2 0.10 0.17 - - - -
- - - - - - - - - 7 34 0.21 -
- - - - - - - - - 9.5 34 0.28 -
no. BW599 126.1 72.4 - 0.57 - - 9.5 0.08 0.13 - - - -
104.3 60.1 - 0.58 - - 8.2 0.08 0.14 11 48.2 0.23 0.8
- 48.2 - - - - 6.8 - 0.14 7.3 37.7 0.19 0.78
Unregistered specimen (coll. Frasali) 154.1 92.9 45.4 0.6 0.29 0.49 17.9 0.12 0.19 - - - -
- - - - - - - - - 7.2 49.9 0.14 -
no. 131H 170 90 - 0.53 - - - - - - - - -
- 78 - - - - - - - 20 52 0.38 0.67
- 60 - - - - - - - 20 42 0.48 0.7
no. K1 1692 (Nikolov & Parashkevanov, 1995) 133 80 53 0.6 0.4 0.66 12 0.09 0.15 16 47 0.34 0.59
- 58 - - - - - - - 14 39 0.36 0.67
no. K1 6001 (Nikolov & Parashkevanov, 1995) 147 97 59 0.66 0.4 0.61 13 0.09 0.13 - - - -
no. K1 6003 (Nikolov & Parashkevanov, 1995) 109 67 - 0.61 - - - - - - - - -
- 55 - - - - - - - 13 37 0.35 0.67
no. K1 6005 (Nikolov & Parashkevanov, 1995) 53 35 24 0.66 0.45 0.69 4 0.08 0.11 - - - -

Description: the studied specimens show a relatively compressed section, with slightly rounded flanks, where maximum thickness is in the lower third. The ventral region is rather narrow and flat or slightly concave. It is lined by two more or less strongly angular ventro-lateral shoulders and shows a clear median keel, especially visible in the last whorl. On the specimen no. Bw599, this median keel seems to appear where the diameter is about 85 mm, later than on the holotype where it is visible from approximately D = 60 mm. The ornamentation is absent on almost all the shell; we observe however some sinuous ribs present only at the adoral part of the body chamber of adult specimens (specimen no. 131H, Pl. XII , fig. 1). The body chamber is only partially preserved on the holotype and probably for this reason there are no ribs present.

The suture line is slightly sinuous, with a shallow lateral lobe (P/L most of the time between 0.20 and 0.35). It crosses the ventral region without forming a ventral lobe, except when the ventral region shows strong shoulders, where it forms a shallow ventral lobe (Fig. 6 ). The siphuncle, visible on specimen no. MHNN 26904 (Pl. XIII , fig. 3), is situated in the dorsal half of the section.

Fig. 6
Click on thumbnail to enlarge the image.

Figure 6: Heminautilus sanctaecrucis Conte, 1980. Suture line of specimens no. MCGL 20747, right side (a), 131H, right side (b), K1 1692, left side (c, d) and Bw599, left side (e, f).

The specimen no. K1 6001, shown by Nikolov & Parashkevanov (1995) and depicted anew (Pl. XIV , fig. 1; Pl. XVI , fig. 1), is tentatively attributed to Heminautilus sanctaecrucis Conte, 1980. It differs from other representatives of the species by the presence of clear rursiradiate ribbing on the top of the flanks of the body chamber and by the shape of its ventral region, lined by two very strong ventro-lateral ridges. This last characteristic may be a consequence of the different mode of preservation of this specimen, where the shell is very well preserved on the ventral region because it is recrystallized, while the other specimens are preserved as internal molds.

Discussion and comparisons: Heminautilus sanctaecrucis Conte, 1980, is a species close to H. lallierianus (Orbigny, 1841) and H. saxbii (Morris, 1848). It can be distinguished from both taxa by its suture line, since the lateral lobe is clearly shallower [P/L is mostly between 0.20 and 0.35 while it is generally between 0.30 and 0.40 for H. saxbii (Morris) and between 0.35 and 0.50 for H. lallierianus (Orbigny)], as well as by the appearance of a keel on the ventral region proximal to the body chamber. H. sanctaecrucis Conte can also be distinguished from H. lallierianus (Orbigny) by a less concave ventral region and by the almost total absence of ornamentation.

H. sanctaecrucis Conte also shows numerous affinities with H. boselliorum Delanoy et al., 2012, with a similar suture line, an identical section and the same type of ornamentation visible at the adoral part of the body chamber. The two can be distinguished by the ventral keel, well defined on the main part of the shell in H. sanctaecrucis Conte while it is very discreet or absent in H. boselliorum Delanoy et al.

The shape of the ventral region of H. sanctaecrucis Conte is also similar to H. rangei (Hoppe, 1922), but can readily be distinguished from it by the absence of ornamentation on the flanks of the main part of the shell.

Heminautilus aff. sanctaecrucis Conte, 1980

Pl. XII , fig. 4

Material studied (N = 1): specimen no. 415951, coll. Baudouin (donated by Vermeulen), Late Barremian, Gerhardtia sartousiana Zone, base of the Hemihoplites feraudianus Subzone, bed 165/041, Angles (Alpes-de-Haute-Provence, France).

Dimensions (in mm): see Table 5.

Table 5: Measurements of Heminautilus aff. sanctaecrucis Conte, 1980.

D H E H/D E/D E/H M M/D M/H P L P/L L/H
no. 415951 58.1 35 - 0.6 - - 4.3 0.07 0.12 - - - -
- 28.6 14.7 - - 0.51 4.5 - 0.16 6.2 21.1 0.29 0.74

Description: small incomplete specimen, consisting of part of the phragmocone and the beginning of the body chamber. The section is narrow, with maximum thickness in the lower third of the flanks, with a flat ventral region with angular edges, and slightly rounded flanks where no ornamentation is visible. On the ventral region, there is a visible yet relatively undeveloped median keel.

The suture line is sinuous, with a wide, round and relatively shallow lateral lobe (Fig. 7 ). The ventral lobe, difficult to observe, seems shallow or absent. The position of the siphuncle is not visible.

Fig. 7
Click on thumbnail to enlarge the image.

Figure 7: Heminautilus aff. sanctaecrucis Conte, 1980. Suture line of specimen no. 415951, right side.

Discussion and comparisons: this specimen has a stratigraphical position intermediate between Heminautilus boselliorum Delanoy et al., 2012, and H. sanctaecrucis Conte, 1980. The suture line and the section of H. aff. sanctaecrucis Conte are identical to those observed in H. boselliorum Delanoy et al. and H. sanctaecrucis Conte; H. aff. sanctaecrucis Conte can be distinguished from H. boselliorum Delanoy et al. by its clearly visible ventral keel, but it is weaker than the one observed in H. sanctaecrucis Conte. Its fragmentary state does not allow us to be more precise on its taxonomic identification.

Heminautilus saxbii (Morris, 1848)

Pl. XV , fig. 2; Pl. XVI , figs. 2-3; Pl. XVII , figs. 1-3; 
Pl. XVIII
, figs. 1-3; Pl. XIX , figs. 1-3; Pl. XX , figs. 1-3; 
Pl. XXI
, figs. 1-4; Pl. XXII , figs. 1-3; Pl. XXIII , figs. 1-4; 
Pl. XXIV
, figs. 1-3; Pl. XXV , figs. 1-4; 
Pl. XXVI
, figs. 1-3; Pl. XXXI , fig. 3

1848

Nautilus saxbii nov. sp. - Morris, p. 106, unnumbered fig.

1870

Nautilus verneuilli nov. sp. - Vilanova, Pl. 3, fig. 4.

pars

1916

Nautilus lallieri Orbigny, 1841 - Douvillé, p. 129, Pl. 17, fig. 5, non figs. 2-4, 6 [= H. rangei (Hoppe, 1922)].

1956

Heminautilus saxbii (Morris, 1848) - Kummel, p. 434, Pl. 10, figs. 1-2.

1964

Heminautilus saxbii (Morris, 1848) - Kummel, p. K454, Fig. 335, 2a-b.

1980

Heminautilus saxbii (Morris, 1848) - Conte, p. 139, Pl. 1, fig. 4b.

1985

Heminautilus saxbii (Morris, 1848) - Conte, p. 30, Fig. 4.

1988

Heminautilus lallierianus (Orbigny, 1841) - Gomez-Alba, p. 356, Pl. 175, fig. 3.

non

1995

Heminautilus saxbii (Morris, 1848) - Nikolov & Parashkevanov, p. 65, Pl. 5, fig. 1, 1a (= ? H. sanctaecrucis Conte, 1980).

non

2002

Heminautilus aff. saxbii (Morris, 1848) - Vermeulen, p. 37 (= H. boselliorum Delanoy et al., 2012).

2003

Heminautilus saxbii (Morris, 1848) - Donovan & Baker, Fig. 3b, f.

?

2006

Heminautilus lallierianus (Orbigny, 1841) - Aly, p. 101, Pl. 1, figs. 1-3.

2006

Heminautilus saxbii (Morris, 1848) - Martínez & Grauges, p. 22, Figs. 3b, 5a-d.

2006

Heminautilus tejeriensis nov. sp. - Martínez & Grauges, p. 24, Figs. 3c, 4a, 6a, 7a-b.

pars

2007

Heminautilus saxbii (Morris, 1848) - Conte, p. 11, photos 1-2, 11, 12?.

2007

Heminautilus saxbii (Morris, 1848) - Moreno et al., Figs. 16-17.

2010

Heminautilus saxbii (Morris, 1848) - Conte, p. 117, Figs. 1-2, 4-5.

2011

Heminautilus saxbii (Morris, 1848) - Peropadre Medina, Fig. 3.12A, B.

Material studied (N = 101): specimens no. EM700, Early Aptian?, Bir Lagama, Gabal Maghara (Egypt); no. PNRL 1189, Early Aptian, Deshayesites forbesi Zone, Murs (Vaucluse, France); no. PM1, PM2, PM3, PM4, PM5, PM6, PM13, PM3N1, PM3N2, PM3N11, PMBb2, coll. MNHN, no. A-114, A-117, A-119, A-122, A-127, A-131, A-140, A-144, A-145, A-146, AG-3, AG-13, JM-26, JM-34, JM-36, JM-37, JM-38, M-8, PUAB 5905, PUAB 48011, PUAB 48013, PUAB 48018, PUAB 48027, PUAB 48035, PUAB 48037, PUAB 48040, PUAB 48042, PUAB 48043, PUAB 48044, PUAB 48046, PUAB 48064, PUAB 48074, PUAB 48080, PUAB 48092, PUAB 48098, PUAB 48106, PUAB 48125, PUAB 48127, PUAB 48128, PUAB 48133, PUAB 48143, PUAB 48158, PUAB 48163, PUAB 48164, PUAB 48165, PUAB 48169, PUAB 48202, PUAB 48205, PUAB 48215, PUAB 48223, PUAB 48232, PUAB 48242, PUAB 48246, PUAB 48254, PUAB 48255, PUAB 48256, PUAB 48261, PUAB 48275, PUAB 48277, PUAB 48278, PUAB 48282, PUAB 48288, PUAB 48292, PUAB 48295, PUAB 48304, PUAB 48314, PUAB 48316, PUAB 48318, PUAB 48321, PUAB 48322, PUAB 48328, PUAB 48366, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain); no. PUAB 48177, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Alacón, Province of Teruel (Spain); no. PUAB 89786, PUAB 89787, PUAB 89788, PUAB 89790, PUAB 89791, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Galve, Province of Teruel (Spain); no. PUAB 88767, PUAB 88770, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Tolodella, Maestrat Basin (Spain); no. MV 423.1, MV 428.2, MV 428.3, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Mola Murada, Maestrat Basin (Spain); no. PUAB 88762, PUAB 88763, Early Aptian, Cabo Marls Formation, Deshayesites forbesi Zone, Lo Pui, Organyà Basin (Spain); no. PUAB 88372, PUAB 88373, Early Aptian, Patrocinio Formation, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Cuchía, Basque Cantabrian Basin (Spain); no. MB RE1962A, Early Aptian, Tibú Formation, Seboruco section (east of Mérida, Venezuela).

Type: the holotype (by monotypy) is the specimen illustrated by Morris (1848) p. 106, stored in the Saxby collection at the British Museum of National History with the no. BMNH 47019. It comes from the Early Aptian of the Isle of Wight (England) and is depicted anew here Pl. XVI , fig. 2.

Geographical distribution: the species is known from England, France, Spain and Egypt. It may be present in Venezuela (specimen no. MB RE1962A, Pl. XXIV , fig. 3).

Stratigraphical distribution: the type of Morris comes from the Lower Greensand, "Crackers' group" of Atherfield, Isle of Wight and is dated as the Deshayesites forbesi Zone; it most certainly comes from the Lower Lobster Beds Formation (Simpson, written communication, 2013), corresponding to the bottom of the Roloboceras hambrovi Subzone (Simpson, 1985; Casey et al., 1998). All the Spanish specimens studied here come from levels dated as the Deshayesites forbesi Zone, Roloboceras hambrovi Subzone (Moreno et al., 2007). The Egyptian specimen no. EM700 is assigned by Douvillé (1916) to the Early Aptian, as well as the specimens displayed in Aly (2006); however, a stratigraphical position in the top of the Late Barremian cannot be excluded. The specimens quoted by Nikolov & Parashkevanov (1995; coll. MPUS) in the Early Barremian (no. K1 1693 and no. K1 1694, displayed anew Pl. VII , figs. 1-2; Pl. IX , fig. 1) and the Late Barremian (no. K1 6005) belong to taxa different from Heminautilus saxbii (Morris, 1848). The specimen no. K1 6005 probably belongs to H. sanctaecrucis Conte, 1980; however, without a visible suture line and with a very weak ventral keel confirmation is not possible. The specimens no. K1 1693 and no. K1 1694 belong to H. boselliorum Delanoy et al., 2012, as does the specimen of H. aff. saxbii (Morris) of Vermeulen (2002, p. 37; figured here Pl. VI , fig. 2; Pl. VII , fig. 4) in the Kotetishvilia nicklesi Zone. The specimens of H. saxbii (Morris) of southeast France [specimens displayed by Conte (2007, 2010) and specimen no. 12576, coll. FSM, shown Pl. XXIV , fig. 1; Pl. XXV , fig. 1] come from the Early Aptian without more precision. Finally, specimen no. MB RE1962A, tentatively attributed to H. saxbii (Morris), comes from the Seboruco section (Venezuela). This section also yielded ammonites attributed to the genus Roloboceras Casey, 1954, by Renz (1982, p. 19), but which more likely belong to the genus Cheloniceras Hyatt, 1903; the stratigraphical position of this specimen can thus be situated approximately in the top of the Early Aptian.

Heminautilus saxbii (Morris, 1848) is thus a species present in the Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, in particular in the bottom of the subzone. The existence of older or more recent representatives of the species remains doubtful and remains to be confirmed.

Dimensions (in mm): see Table 6.

Table 6: Measurements of Heminautilus saxbii (Morris, 1848).

D H E H/D E/D E/H M M/D M/H P L P/L L/H
Holotype no. BMNH 47019 86 56 32 0.65 0.37 0.57 7 0.08 0.13 - - - -
69 42 - 0.61 - - 8 0.12 0.19 13 31 0.42 0.74
52 31 - 0.60 - - 6 0.12 0.19 8 23 0.35 0.74
no. EM700 128.6 83.6 49.2 0.65 0.38 0.59 12.2 0.09 0.15 - - - -
90.6 57.8 35.1 0.64 0.39 0.61 9.8 0.11 0.17 14.5 42.4 0.34 0.73
no. PNRL 1189 - 87.2 43.3 - - 0.50 13.7 - 0.16 - - - -
- 77.5 30.5 - - 0.39 9.7 - 0.13 14.7 57.1 0.26 0.74
no. 12576 197 118 50 0.60 0.25 0.42 - - - - - - -
145 100 - 0.69 - - - - - 32 70 0.46 0.70
- 89 - - - - - - - 25 67 0.37 0.74
no. PM1 138 85 51 0.62 0.37 0.60 20 0.14 0.24 - - - -
- 63 36 - - 0.57 9 - 0.14 17 49 0.35 0.78
- 46 30 - - 0.65 8 - 0.17 11 36 0.31 0.78
no. PM2 126 - 45 - 0.36 - 16 0.13 - - - - -
98 - 33 - 0.34 - 7 0.07 - 14 45 0.31 -
no. PM3 129 81 54 0.63 0.42 0.67 19 0.15 0.23 - - - -
no. PM4 81 53 29 0.65 0.36 0.55 9 0.11 0.17 13 38 0.34 0.72
67 43 25 0.64 0.37 0.58 8 0.12 0.19 10 31 0.32 0.72
no. PM5 144 c87 55 0.60 0.38 0.63 20 0.14 0.23 - - - -
- c58 35 - - 0.60 8 - 0.14 15 40 0.38 0.69
no. PM6 125 80 - 0.64 - - 11 0.09 0.14 - - - -
106 67 36 0.63 0.34 0.54 8 0.08 0.12 17 50 0.34 0.75
81 50 31 0.62 0.38 0.62 7 0.09 0.14 14 40 0.35 0.80
no. PM13 146 87 - 0.60 - - 18 0.12 0.21 - - - -
109 65 38 0.60 0.35 0.58 8 0.07 0.12 18 49 0.37 0.75
- 52 32 - - 0.62 7 - 0.13 12 37 0.32 0.71
no. PM3N1 - 74 39 - - 0.53 11 - 0.15 20 54 0.37 0.73
- 53 31 - - 0.58 8 - 0.15 14 37 0.38 0.70
no. PM3N2 118 75 38 0.64 0.32 0.51 10 0.08 0.13 - - - -
114 72 38 0.63 0.33 0.53 9 0.08 0.13 20 54 0.37 0.75
74 48 29 0.65 0.39 0.60 7 0.09 0.15 12 35 0.34 0.73
no. PM3N11 97 60 36 0.62 0.37 0.60 11 0.11 0.18 - - - -
72 44 29 0.61 0.40 0.66 8 0.11 0.18 9 34 0.26 0.77
no. PMBb2 - 51 29 - - 0.57 7 - 0.14 11 41 0.27 0.80
- 41 26 - - 0.63 6 - 0.15 10 33 0.30 0.80
no. A-114 106.3 66.2 - 0.62 - - 10.5 0.10 0.16 16.6 49.2 0.34 0.74
- 43.7 33.3 - - 0.76 9.5 - 0.22 9.4 29.9 0.31 0.68
no. A-145 116.7 70.0 43.5 0.6 0.37 0.62 11.6 0.10 0.17 14.6 49.9 0.29 0.71
85.5 49.9 - 0.58 - - 10.8 0.13 0.22 12.9 37.1 0.35 0.74
no. A-146 84.9 50.1 - 0.59 - - 8.1 0.10 0.16 14.4 38.9 0.37 0.78
72.5 41.8 - 0.58 - - - - - 11.8 33.3 0.35 0.8
- 26.2 - - - - - - - 6.7 20.5 0.33 0.78
no. AG-3 99.8 61.9 - 0.62 - - 8.0 0.08 0.13 17.2 45.7 0.38 0.74
no. AG-13 52.7 30.8 23.1 0.58 0.44 0.75 7.2 0.14 0.23 8.2 22.8 0.36 0.74
- 21.2 - - - - 5.7 - 0.27 5.0 15.8 0.32 0.74
no. JM-34 117.1 73.1 47.8 0.62 0.41 0.65 12.3 0.10 0.17 22.5 51.3 0.44 0.7
- 32.9 - - - - 7.5 - 0.23 9.1 25.4 0.36 0.77
no. JM-36 127 74 50 0.58 0.39 0.68 - - - - - - -
no. M-8 - 67.0 39.1 - - 0.58 10.0 - 0.15 15.7 48.0 0.33 0.72
no. PUAB 5905 - 56.2 - - - - 8.7 - 0.15 12.5 38.6 0.32 0.69
- 33.6 - - - - 5.4 - 0.16 6.6 25.0 0.26 0.74
no. PUAB 48011 99.8 59.3 - 0.59 - - 9.4 0.09 0.16 16.2 43.8 0.37 0.74
no. PUAB 48013 113.0 73.0 - 0.65 - - - - - 16.5 51.4 0.32 0.7
- 44.9 30.4 - - 0.68 8.4 - 0.19 11.1 33.8 0.33 0.75
- 36.9 - - - - 7.7 - 0.21 8.5 28.0 0.3 0.76
no. PUAB 48027 94.1 59.8 - 0.64 - - 8.2 0.09 0.14 15.1 44.1 0.34 0.74
no. PUAB 48040 - 48.9 32.3 - - 0.66 8.5 - 0.17 13.9 36.5 0.38 0.75
- 39.2 27.6 - - 0.7 8.1 - 0.21 10.8 30.5 0.35 0.78
- 34.2 25.4 - - 0.74 7.5 - 0.22 7.9 25.1 0.32 0.73
no. PUAB 48042 126 69 49 0.55 0.39 0.71 17 0.13 0.25 - - - -
c99 59 - 0.60 - - 12 0.12 0.20 17 45 0.38 0.76
- 44 - 0.44 - - - - - 13 33 0.39 0.75
no. PUAB 48044 120 68 45 0.57 0.38 0.66 - - - - - - -
99.2 61.7 35.1 0.62 0.35 0.57 8.3 0.08 0.13 18.7 44.6 0.42 0.72
85.6 49.8 34.3 0.58 0.4 0.69 9.5 0.11 0.19 14.7 35.1 0.42 0.71
119.3 40.9 31.4 0.34 0.26 0.77 8.4 0.07 0.21 11.0 29.6 0.37 0.72
no. PUAB 48046 136 80 60 0.59 0.44 0.75 - - - - - - -
no. PUAB 48098 - 47.4 31.3 - - 0.66 9.4 - 0.20 13.5 39.3 0.34 0.83
no. PUAB 48128 153 90 49 0.59 0.32 0.54 - - - - - - -
no. PUAB 48143 - 27.6 17.5 - - 0.63 4.7 - 0.17 8.4 19.6 0.43 0.71
no. PUAB 48163 60.8 35.1 - 0.58 - - 7.6 0.13 0.22 8.0 25.5 0.31 0.73
no. PUAB 48164 81.5 52.9 34.3 0.65 0.42 0.65 7.7 0.09 0.15 14.0 36.1 0.39 0.68
76.7 47.9 29.9 0.62 0.39 0.62 6.7 0.09 0.14 11.6 34.7 0.33 0.72
no. PUAB 48205 - 54.6 35.4 - - 0.65 8.5 - 0.16 14.8 33.5 0.44 0.61
no. PUAB 48215 109.8 69.5 37.2 0.63 0.34 0.53 8.9 0.08 0.13 14.7 51.6 0.28 0.74
- 51.0 - - - - 8.9 - 0.17 11.3 37.2 0.3 0.73
- 37.9 - - - - 8.2 - 0.22 8.6 29.8 0.29 0.78
no. PUAB 48202 - 51.9 36.1 - - 0.7 7.8 - 0.15 15.3 36.1 0.43 0.7
- 36.1 27.3 - - 0.76 - - - 11.7 30.1 0.39 0.83
no. PUAB 48246 - 49.4 34.4 - - 0.7 - - - 14.0 36.5 0.38 0.74
no. PUAB 48254 - 63.9 - - - - 9.6 - 0.15 12.4 46.1 0.27 0.72
no. PUAB 48255 - 63.5 37.8 - - 0.59 9.0 - 0.14 18.2 43.5 0.42 0.68
- 42.0 26.4 - - 0.63 7.5 - 0.18 11.8 30.9 0.38 0.74
no. PUAB 48256 - 49.4 31.5 - - 0.64 8.1 - 0.16 13.9 38.7 0.36 0.78
no. PUAB 48261 - 71.9 44.0 - - 0.61 9.2 - 0.13 19.1 46.6 0.41 0.65
- 65.3 40.6 - - 0.62 8.8 - 0.13 17.6 42.2 0.42 0.65
- 56.8 35.0 - - 0.62 8.2 - 0.14 16.2 39.2 0.41 0.69
no. PUAB 48275 - 76.7 - - - - 12.4 - 0.16 16.5 52.3 0.32 0.68
no. PUAB 48292 128 76 56 0.59 0.44 0.74 17 0.13 0.22 - - - -
111.8 68.6 38.5 0.61 0.34 0.56 10.5 0.09 0.15 14.6 49.6 0.29 0.72
109.0 63.5 37.5 0.58 0.34 0.59 9.9 0.09 0.16 15.2 49.6 0.31 0.78
no. PUAB 48295 - 53.8 - - - - 8.5 - 0.16 16 42 0.38 0.78
no. PUAB 48366 - 65.2 - - - - 11.8 - 0.18 15.3 48.3 0.32 0.74
- 61.4 - - - - 9.4 - 0.15 14.2 47.1 0.3 0.77
no. PUAB 89788 - 66.0 - - - - 10.3 - 0.16 16.1 45.5 0.35 0.69
- 60.0 34.4 - - 0.57 9.9 - 0.16 15.1 42.8 0.35 0.71
- 46.5 29.3 - - 0.63 19.1 - 0.41 13.0 35.9 0.36 0.77
no. PUAB 89791 - 62.2 31.6 - - 0.51 9.7 - 0.16 16.7 47.0 0.35 0.76
no. PUAB 48009 (Martinez & Grauges, 2006) 85 52 33 0.61 0.39 0.63 - - - - - - -
no. PUAB 48093 (Martinez & Grauges, 2006) 147 80 56 0.54 0.38 0.70 - - - - - - -
no. PUAB 48095 (Martinez & Grauges, 2006) 65 42 26 0.65 0.40 0.62 - - - - - - -
Specimen photo 11 (Conte, 2007) - 73 - - - - - - - 20 58 0.34 0.79
Specimen Fig. 3.12 (Peropadre Medina, 2011) - 58 - - - - 12 - 0.21 16 48 0.33 0.83
Holotype of Nautilus verneuilli Vilanova, 1870 118 76 38 0.64 0.32 0.50 2 0.02 0.03 - - - -
112 71 - 0.63 - - 4 0.04 0.06 18 54 0.33 0.76
89 57 - 0.64 - - 5 0.06 0.09 14 47 0.30 0.82
no. MB RE1962A - 47 - - - - - - - 10 32 0.31 0.68
- 45 - - - - 7 - 0.16 12 32 0.38 0.71

Description: the studied specimens show a relatively compressed section (E/H generally between 0.50 and 0.70), with slightly convex flanks, with maximum thickness located in the lower third of the flanks. The ventral region is relatively narrow; convex in the inner whorls (specimen no. PUAB 48158, Pl. XXIII , fig. 3), it quickly becomes slightly concave or flat, with angular edges, or very slightly convex on the body chamber of some specimens (holotype of Heminautilus tejeriensis Martínez & Grauges, 2006, no. PUAB 48292; Pl. XXVI , fig. 1). In the most internal whorls, rursiradiate fine growth riblets are visible on the flanks and the ventral region where they form an angular chevron (no. PUAB specimen 48158, Pl. XXXI , fig. 3); no other ornamentation is visible on the phragmocone. On the body chamber of adult specimens, strongly rursiradiate ribs appear in the upper half of the flanks, more or less broad and high (specimens no. A-127, Pl. XVII , fig. 2; no. MV 428.3, Pl. XIX , fig. 1; no. MV 428.2, Pl. XXI , fig. 1; no. PUAB 48042, Pl. XXIII , fig. 1).

The suture line is sinuous (Fig. 8 ), with a wide and relatively deep lateral lobe (P/L generally between 0.30 and 0.40) and a fairly narrow and angular lateral saddle, becoming round with growth. The ventral lobe is shallow or absent.

Fig. 8
Click on thumbnail to enlarge the image.

Figure 8: Heminautilus saxbii (Morris, 1848). Suture line of specimens no. BMNH 47019, right side (a-c), EM700, left side (d) and PM1, right side (e).

The siphuncle, particularly visible in the specimen no. PMBb2 (Pl. XVII , fig. 3), is located between the dorsum and the center of the section, near the dorsal region.

Variability: the number of specimens of Heminautilus saxbii (Morris, 1848) studied here, with a particularly important sample from Josa, Province of Teruel (Spain), allows estimation of the variability of the species. The variability essentially concerns the width of the conch (Fig. 9 ), the shape of the ventral region, the ornamentation and the plan of the suture line. The thickness of the shell varies from compressed forms where E/H is about 0.50 (specimen no. PUAB 89791) to wide forms where E/H reaches 0.76 (specimen no. PUAB 48044, Pl. XXVI , fig. 2). The shape of the ventral region varies from slightly concave to flat, even very slightly convex. The ornamentation of the body chamber of the adult specimens is also rather variable, being almost smooth (specimen no. PM13, Pl. XXII , fig. 1), or with broad and well defined ribs (specimens no. MV 428.3, Pl. XIX , fig. 1; no. MV 428.2, Pl. XXI , fig. 1), with intermediate forms with very visible but narrower and weaker ribs (specimen no. PUAB 48042, Pl. XXIII , fig. 1). Finally, the suture line shows a lateral lobe of variable depth, with P/L between 0.26 (specimen no. PM3N11, Pl. XXI , fig. 2) and 0.44 (specimen no. JM-34, Pl. XIX , fig. 3), and a shallow to absent ventral lobe.

Fig. 9
Click on thumbnail to enlarge the image.

Figure 9: E/H in function of H. In red, Heminautilus lallierianus (Orbigny, 1841); in orange, Heminautilus aff. lallierianus (Orbigny, 1841); in blue, Heminautilus saxbii (Morris, 1848); in green, specimens attributed to Heminautilus tejeriensis Martínez & Grauges, 2006 [= H. saxbii (Morris)] by Martínez & Grauges (2006). When taken at various diameters, measurements of the same specimen are connected by a line. The enlarged symbols represent the respective type specimens.

Discussion and comparisons: Heminautilus saxbii (Morris, 1848) is particularly close to Heminautilus lallierianus (Orbigny, 1841). The latter can be distinguished from H. saxbii (Morris) by its clearly more sinuous suture line, showing a deeper and narrower lateral lobe (P/L generally near 0.35 - 0.50; Fig. 10 ; L/H generally between 0.70 and 0.80 in H. saxbii (Morris), between 0.60 and 0.75 in H. lallierianus (Orbigny); Fig. 11 ) and a wider and rounded lateral saddle, as well as by the shape of the strongly concave ventral region which contains a deep ventral lobe. The shell of H. lallierianus (Orbigny) is also more compressed (Fig. 12 ) than that of H. saxbii (Morris), with E/H generally between 0.40 and 0.60 in H. lallierianus (Orbigny) and between 0.50 and 0.70 in H. saxbii (Morris). According to numerous authors these species are synonyms (Orbigny, 1850; F.-J. Pictet & Campiche, 1858; Douvillé, 1916; Scott, 1943) while other later authors consider them distinct (Conte, 1980, 1985, 2007; Martínez & Grauges, 2006). In Europe both taxa occupy very close stratigraphical positions within the Deshayesites forbesi Zone, Roloboceras hambrovi Subzone. This leads us to two possible hypotheses: either the taxa represent two morphological poles of the same relatively variable species, or they represent two distinct species.

Fig. 10
Click on thumbnail to enlarge the image.

Figure 10: P/L in function of H. In red, Heminautilus lallierianus (Orbigny, 1841); in orange, Heminautilus aff. lallierianus (Orbigny, 1841); in blue, Heminautilus saxbii (Morris, 1848); in green, specimens attributed to Heminautilus tejeriensis Martínez & Grauges, 2006 [= H. saxbii (Morris)] by Martínez & Grauges (2006). When taken at various diameters, measurements of the same specimen are connected by a line. The enlarged symbols represent the respective type specimens.

Fig. 11
Click on thumbnail to enlarge the image.

Figure 11: L/H in function of H. In red, Heminautilus lallierianus (Orbigny, 1841); in orange, Heminautilus aff. lallierianus (Orbigny, 1841); in blue, Heminautilus saxbii (Morris, 1848); in green, specimens attributed to Heminautilus tejeriensis Martínez & Grauges, 2006 [= H. saxbii (Morris)] by Martínez & Grauges (2006). When taken at various diameters, measurements of the same specimen are connected by a line. The enlarged symbols represent the respective type specimens.

Fig. 12
Click on thumbnail to enlarge the image.

Figure 12: E in function of H. In red, Heminautilus lallierianus (Orbigny, 1841); in orange, Heminautilus aff. lallierianus (Orbigny, 1841); in blue, Heminautilus saxbii (Morris, 1848); in green, specimens attributed to Heminautilus tejeriensis Martínez & Grauges, 2006 [= H. saxbii (Morris)] by Martínez & Grauges (2006). When taken at various diameters, measurements of the same specimen are connected by a line. The enlarged symbols represent the respective type specimens.

The study of numerous specimens coming from the section of Josa (Province of Teruel, Spain) establishes that, of these specimens, almost all are unambiguously morphologically attributable to H. saxbii (Morris) and that the morphologies of lallierianus (Orbigny) type are almost absent. These taxa do not appear to coexist and occupy slightly different stratigraphic positions in Europe within the Roloboceras hambrovi Subzone. On the Isle of Wight, the holotype and an important population of H. saxbii (Morris) were collected in the Lower Lobster Beds Formation (Simpson, written communication, 2013) and are thus situated in the bottom of the Roloboceras hambrovi Subzone (Simpson, 1985; Casey et al., 1998). The population of H. saxbii (Morris) from the section of Josa comes from a slightly condensed level attributed to the Roloboceras hambrovi Subzone (Moreno et al., 2007); however, the dominance of the genus Roloboceras Casey, 1954, and the scarcity of the genus Megatyloceras Humphrey, 1949, among Roloboceratinae of this level indicate a stratigraphical position in the bottom of the Roloboceras hambrovi Subzone (equivalent to the Lower Lobster Beds Formation of the Isle of Wight). On the other hand, the small population of H. lallierianus (Orbigny) of Le Teil and Viviers (Ardèche, France), where no typical specimen of H. saxbii (Morris) is known, is associated with numerous Megatyloceras Humphrey and is probably situated at the top of the Roloboceras hambrovi Subzone (equivalent of the Upper Lobster Beds Formation of the Isle of Wight; Casey et al., 1998).

So, although the two taxa are undoubtedly phyletically very close, they never coexist in the localities studied here. Consequently, H. lallierianus (Orbigny) represents a species separate from H. saxbii (Morris), which it probably replaces within the Roloboceras hambrovi Subzone in Europe.

On the other hand, the important sample from Josa allows us to consider Heminautilus tejeriensis Martínez & Grauges, 2006, as a junior synonym of H. saxbii (Morris, 1848). In the original description, H. tejeriensis Martínez & Grauges was characterized essentially by the shape of its ventral region, flat or very slightly convex, as well as by the absence of a ventral lobe, while H. saxbii (Morris) shows a slightly concave to flat ventral region, with a shallow ventral lobe. Other than the ventral region, the suture lines of both taxa are identical. However, these slight differences appear to represent only minor intraspecific variability within the one species. Indeed, we frequently observe, on the same specimen [in particular in the holotype of H. saxbii (Morris)], some suture lines forming a lobe at the passage of the ventral region while others cross it straight, or even form a slight convexity (specimen no. PUAB 48044, Pl. XXV , fig. 4; Pl. XXVI , fig. 2). Most of the specimens attributed to H. tejeriensis Martínez & Grauges show a flat ventral region identical to that of the holotype of H. saxbii (Morris). Only the holotype of H. tejeriensis Martínez & Grauges shows a very slight convexity that solely affects the ventral region of the body chamber; this singular characteristic does not appear to justify a differentiation at the species level. Furthermore, all specimens attributed to H. tejeriensis Martínez & Grauges come from the Province of Teruel (Spain) where they are associated with numerous clearly coeval specimens of H. saxbii (Morris). The contemporaneity of these two taxa and minimal morphological differences lead us to consider them as the expression of a slight intraspecific variability within the species H. saxbii (Morris).

Also, Heminautilus verneuilli (Vilanova, 1870), whose holotype also comes from Josa, Province of Teruel (Spain), shows characteristics identical to those of H. saxbii (Morris). Following Martínez & Grauges (2006), we consider this taxon as a junior synonym of H. saxbii (Morris). The original illustration of Vilanova (1870) is reproduced here (Pl. XXVI , fig. 3).

Heminautilus saxbii (Morris) is also close to H. boselliorum Delanoy et al., 2012, and H. sanctaecrucis Conte, 1980. The differences with these two species were highlighted in the pertinent sections.

Remarks: the specimen no. MB RE1962A (Seboruco section, Venezuela; Pl. XXIV , fig. 3) shows morphological and sutural characteristics that lead us to attribute it to H. saxbii (Morris). However, the presence of Heminautilus etheringtoni Durham, 1946 (specimen no. MB RE1962a, Pl. XXXII , fig. 2), in the same section makes this attribution tentative; this specimen may also represent a slender variant of H. etheringtoni Durham. Only the study of a more representative population of this last taxon would provide more certainty about its variability.

Heminautilus lallierianus (Orbigny, 1841)

Pl. XXVII , figs. 1-2; Pl. XXVIII , figs. 1-3; Pl. XXIX , figs. 1-3; 
Pl. XXX
, figs. 1-2; Pl. XXXI , figs. 1-2; Pl. XXXII , fig. 1; 
Pl. XXXIII
, fig. 1; Pl. XXXIV , fig. 1; Pl. XXXV , figs. 1-2; 
Pl. XXXVI
, fig. 1; Pl. XXXVII , fig. 1; Pl. XXXVIII , fig. 1; 
Pl. XL
, fig. 2; Pl. XLI , fig. 1

1841

Nautilus lallierianus nov. sp. - Orbigny, p. 318

non

1858

Nautilus lallierianus Orbigny, 1841 - F.-J. Pictet & Campiche, p. 148, Pl. 19, fig. 6 (= H. sanctaecrucis Conte, 1980).

non

1916

Nautilus lallieri Orbigny, 1841 - Douvillé, p. 129, Pl. 17, figs. 2-6 [figs. 2-4, 6 = H. rangei (Hoppe, 1922); fig. 5 = H. saxbii (Morris, 1848)].

1943

Heminautilus lallieri (Orbigny, 1841) - Scott, p. 90, Pl. 25, fig. 2.

non

1967

Xenocheilus lallierianus (Orbigny, 1841) - Dimitrova, p. 18, Pl. 4, fig. 1 (= H. sanctaecrucis Conte, 1980).

non

1976

Heminautilus lallierianus (Orbigny, 1841) - Obata & Ogawa, p. 103, Fig. 7a-c; Pl. 2, fig. 3 (= H. ? japonicus sp. nov.).

1980

Heminautilus lallierianus (Orbigny, 1841) - Conte, Pl. 1, Figs. 3, 4c.

non

1984

Heminautilus cf. H. lallierianus (Orbigny, 1841) - Obata et al., p. 30, Fig. 3; Pl. 5, fig. 1a-b; Pl. 6, fig. 1 (= H. ? japonicus sp. nov.).

1985

Heminautilus lallierianus (Orbigny, 1841) - Conte, p. 30, Pl. 1, figs. 1-5.

non

2006

Heminautilus lallierianus (Orbigny, 1841) - Aly, p. 101, Pl. 1, figs. 1-3 [= ? H. saxbii (Morris, 1848)].

2007

Heminautilus lallierianus (Orbigny, 1841) - Conte, p. 10, photos 1-7, 9, 10.

non

2008

Heminautilus lallierianus (Orbigny, 1841) - Abu-Zied, Fig. 3, A-C [= H. rangei (Hoppe, 1922)].

2008

Heminautilus lallierianus (Orbigny, 1841) - Moreno et al., Fig. 4.

2012

Heminautilus lallierianus (Orbigny, 1841) - Delanoy et al., Pl. 1, fig. 2.

Material studied (N = 17): lectotype no. MNHN.F.A32800, Early Aptian, top of the Deshayesites forbesi Zone?, Gurgy (Yonne, France); specimen no. UPMC-250, Early Aptian, top of the Deshayesites forbesi Zone?, Gurgy (Yonne, France); specimens no. tl028, tl029, tl056, tl069, tl078, tl079, tl080, coll. Baudouin, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Le Teil (Ardèche, France); no. BRG098, BRG103, coll. Baudouin, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, bed no. 12, Pierrelatte section (Drôme, France; cf. A. Pictet et al., 2009, Fig. 2); no. VI009, VI012, coll. Boselli, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Viviers (Ardèche, France); no. MPP.B-EM.69, coll. FSM, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, bed no. 148, La Bédoule (Bouches du Rhône, France); no. PM95, coll. MNHN, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain); no. PUAB 89780, Early Aptian, probably Deshayesites forbesi Zone, El Vendrell, Garraf (Spain); no. MGB 22607, Early Aptian, Garraf (Spain).

Type: the species was created by Orbigny (1841) with no illustration and without designation of holotype; a specimen was shown by Conte (1980, 2007) with the description "type"; the same specimen was depicted anew by Delanoy et al. (2012) with the description "holotype". It is the syntype no. MNHN.F.A32800, coll. Orbigny (no. 5573) stored in the Muséum d'Histoire Naturelle of Paris, which we therefore designate as the lectotype. It is shown in this work as Pl. XXIX , fig. 1 and comes from the Early Aptian of Gurgy (Yonne, France).

Geographical distribution: the species seems to be known with certainty only from France, Spain and Ethiopia.

Stratigraphical distribution: the lectotype and the topotypes no. 77-543, no. 85-3 (coll. MHNA) and no. UPMC-250 come from the Argiles à Plicatules Formation of Gurgy (Yonne), where the accompanying ammonite fauna indicates a stratigraphical position between the top of the Deshayesites forbesi Zone and the Deshayesites deshayesi Zone (Corroy, 1925; Amédro & Matrion, 2004). However, the preservation of these four specimens, as calcareous moulds of relatively large size, differs from that typically encountered in the form of pyritic nucleus and could be characteristic of a particular level within the Argiles à Plicatules. The holotype of Roloboceras transiens Casey, 1961, with the same preservation and from the same locality, suggests a stratigraphical position of this level in the top of the Deshayesites forbesi Zone, Roloboceras hambrovi Subzone. Specimens no. tl028, tl029, tl056, tl069, tl078, tl079 and VI009, collected in association with numerous representatives of the genus Megatyloceras Humphrey, 1949, come from the top of the Roloboceras hambrovi Subzone (Casey et al., 1998). Specimens no. BRG098 and BRG103, from bed no. 12 of the Pierrelatte section, would come from the lower part of the Roloboceras hambrovi Subzone (A. Pictet et al., 2009, 2015). Specimen no. AMNH 25455 depicted by Scott (1943) comes from the Harrar region (Ethiopia). The local geology was studied by Bosellini et al. (1999), who show that in this region there is only a very short Aptian marine incursion, with sandy fluvial deposition before and after; the presence of Palorbitolina lenticularis (Blumenbach, 1805) and Praeorbitolina cormyi Schroeder, 1964, allows us to determine a middle Early Aptian age for this formation (Schroeder et al., 2010). Heminautilus lallierianus (Orbigny, 1841) is thus present in Europe in the Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, in particular at the top of the subzone.

Dimensions (in mm): see Table 7.

Table 7: Measurements of Heminautilus lallierianus (Orbigny, 1841).

D H E H/D E/D E/H M M/D M/H P L P/L L/H
Lectotype no. MNHN.F.A32800 124 81 44 0.55 0.30 0.54 9 0.06 0.11 24 44 0.55 0.54
- 68 - - - - - - - 20 40 0.50 0.59
- 48 - - - - - - - 15 30 0.50 0.63
no. 77-543 176 104 62 0.59 0.35 0.60 - - - - - - -
112 70 - 0.63 - - 10 0.09 0.14 22 48 0.46 0.69
no. 85-3 - 67 39 - - 0.58 9 - 0.13 17 39 0.44 0.58
- 47 - - - - 8 - 0.17 15 29 0.52 0.62
no. UPMC-250 - 42.7 - - - - 6.8 - 0.16 11.8 29.9 0.39 0.70
- 66 - - - - 9.6 - 0.15 16.8 43.8 0.38 0.66
no. tl028 67 40 19 0.60 0.28 0.48 12 0.18 0.30 - - - -
55 33 18 0.60 0.33 0.55 6 0.11 0.18 9 24 0.38 0.73
49 30 16 0.61 0.33 0.53 6 0.12 0.20 8 23 0.35 0.77
no. tl029 154 96 57 0.62 0.37 0.59 13 0.08 0.14 - - - -
122 87 38 0.71 0.31 0.44 8 0.07 0.09 18 54 0.33 0.62
119 82 - 0.69 - - 6 0.05 0.07 19 53 0.36 0.65
- 68 - - - - - - - 20 48 0.42 0.71
no. tl056 153 93 55 0.61 0.36 0.59 13 0.08 0.14 - - - -
135 89 - 0.66 - - 10 0.07 0.11 24 60 0.40 0.67
- 57 - - - - c6 - 0.11 20 43 0.47 0.75
no. tl069 159 97 c51 0.61 0.32 0.53 11 0.07 0.11 - - - -
c132 85 c37 0.64 0.28 0.44 6 0.05 0.07 23 57 0.40 0.67
no. tl078 173.9 108 64.9 0.62 0.37 0.60 11.3 0.06 0.10 - - - -
128.9 89.3 38.4 0.69 0.30 0.43 7.4 0.06 0.08 23.4 56 0.42 0.63
no. tl079 - 88.3 - - - - 7.4 - 0.08 24.7 58.1 0.43 0.66
no. tl080 - 99.3 62.1 - - 0.63 15.3 - 0.15 - - - -
139.1 91.2 39.1 0.66 0.28 0.43 11.6 0.08 0.13 20.1 53.4 0.38 0.59
no. BRG098 - 41.1 23.8 - - 0.58 6.6 - 0.16 - - - -
- 35.9 18 - - 0.50 4.8 - 0.13 9.7 27.6 0.35 0.77
no. BRG103 134.3 77.5 37.5 0.58 0.28 0.48 7.5 0.06 0.10 - - - -
- 61.8 26.5 - - 0.43 6.2 - 0.10 20.1 53.9 0.37 0.87
no. VI009 148 84 53 0.57 0.36 0.63 15 0.10 0.18 - - - -
122 78 c36 0.64 0.30 0.46 8 0.07 0.10 19 52 0.37 0.67
no. VI012 153 92 60 0.60 0.39 0.65 9 0.06 0.10 - - - -
128 83 43 0.65 0.34 0.52 5 0.04 0.06 22 60 0.37 0.72
- 63 31 - - 0.49 - - - 18 47 0.38 0.75
no. MPP.B-EM.69 58 33.5 12.2 0.58 0.21 0.36 4.9 0.08 0.15 - - - -
no. PM95 159 95 70 0.60 0.44 0.74 17 0.11 0.18 - - - -
128 79 48 0.62 0.38 0.61 13 0.10 0.16 19.5 52 0.38 0.66
- 61 38 - - 0.62 10 - 0.16 17 42 0.40 0.69
no. PUAB 89780 - 46.5 - - - - - - - 16.4 33.9 0.48 0.73
- 42.5 - - - - - - - 15.8 31.8 0.5 0.75
no. AMNH 25455 (Scott, 1943) 146 93 57 0.64 0.39 0.61 - - - - - - -
116 80 - 0.69 - - - - - 28 59 0.47 0.74
- 57 - - - - - - - 13 36 0.36 0.63
no. 12572 145 85 40 0.59 0.28 0.47 - - - - - - -
90 61 - 0.68 - - - - - 19 39 0.49 0.64
- 35 - - - - 4 - 0.11 - - - -
no. 12573 160 95 46 0.59 0.29 0.48 - - - - - - -
c95 65 22 0.68 0.23 0.34 - - - 18 42 0.43 0.65
- 40 - - - - 6.5 - 0.16 14 25 0.56 0.63
Specimen photo 7 (Conte, 2007) c121 69 - 0.57 - - - - - - - - -
- 62 - - - - - - - 21 45 0.47 0.73
no. MGB 22607 (Moreno et al., 2008) c113 70 35 0.62 0.31 0.50 6 0.05 0.09 22 47 0.47 0.67
- 59 - - - - - - - 21 42 0.50 0.71

Description: Heminautilus lallierianus (Orbigny, 1841) has a large shell (D = 176 mm, specimen no. 77-543, Pl. XXX , fig. 1), compressed (E/H generally between 0.40 and 0.60; Fig. 9 ), with slightly rounded flanks, of maximum thickness in the lower third of the flanks. The initial whorls are unknown; from a small diameter, the ventral region is narrow, strongly concave (specimen no. MPP.B-EM.69, Pl. XXXVIII , fig. 3), lined with angular ventro-lateral edges. On the body chamber of adult specimens, the concavity of the ventral region frequently becomes less pronounced (no. 77-543, Pl. XXIX , fig. 2; no. tl078, Pl. XXXV , fig. 2; no. tl029, Pl. XXXVI , fig. 1). No ornamentation is present on the phragmocone. On the body chamber, the ornamentation shows some variability. Some complete adult specimens are completely smooth (no. BRG103, Pl. XXXI , fig. 2; no. tl029, Pl. XXXV , fig. 1; no. tl056, Pl. XXXI , fig. 1; no. VI009, Pl. XXXII , fig. 1; no. tl069, Pl. XXXIII , fig. 1), while others show at the end of the body chamber broad and strongly rursiradiate ribs, restricted to the upper part of the flanks (no. PUAB 89780, Pl. XXVII , fig. 1; no. PM95, Pl. XXXVIII , fig. 1; no. 77-543, Pl. XXX , fig. 1; no. tl078, Pl. XXXIV , fig. 1).

The suture line is strongly sinuous (Fig. 13 ), with a fairly wide and deep lateral lobe (Fig. 11 ; P/L generally between 0.35 and 0.50, Fig. 10 ), a wide and rounded lateral saddle and a well defined, angular ventral lobe. In some specimens, we observe the space between the last suture lines narrowing, characteristic of the adult stage (no. PM95, Pl. XXXVIII , fig. 1; no. tl056, Pl. XXXI , fig. 1). The siphuncle, very visible in the lectotype no. MNHN.F.A32800 (Pl. XXIX , fig. 1) and the specimen no. 85-3 (Pl. XXVII , fig. 2), is placed very low on the section, near the dorsal edge.

Fig. 13
Click on thumbnail to enlarge the image.

Figure 13: Heminautilus lallierianus (Orbigny, 1841). Suture line of specimens no. MNHN.F.A32800, left side (a-b), PM95, right side (c) and tl056, left side (d).

Discussion and comparisons: Heminautilus lallierianus (Orbigny, 1841) is very similar to H. saxbii (Morris, 1848). Relationships between these two taxa were discussed in the section on H. saxbii (Morris, 1848).

The specific characteristics of H. lallierianus (Orbigny), in particular its strongly concave and narrow ventral region, as well as its very sinuous suture line with a deep lateral lobe, readily distinguish it from other species of the genus Heminautilus Spath, 1927.

Heminautilus aff. lallierianus (Orbigny, 1841)

Pl. XXXIX , fig. 1; Pl. XL , fig. 1

2015 Heminautilus cf. lallierianus (Orbigny, 1841) - Moreno-Bedmar et al., p. 209.

Material studied (N = 2): specimen no. IGM 10050, Early Aptian, Dufrenoyia justinae Zone, bed no. 15, Mina Texali, Santa Isabel Atenayuca, Puebla State (Mexico); specimen no. MPL1, Early Aptian, Dufrenoyia justinae Zone, Sierra del Rosario, Durango State (Mexico).

Geographical distribution: Heminautilus aff. lallierianus (Orbigny, 1841) is known only in Mexico.

Stratigraphical distribution: the specimen no. IGM 10050 comes from the Dufrenoyia justinae Zone (= top of the Dufrenoyia furcata Zone, Moreno-Bedmar et al., 2012, 2015). The specimen no. MPL1 comes from the La Peña Formation, corresponding to a stratigraphical interval ranging from the Dufrenoyia justinae Zone to the lowermost part of the Caseyella aguilerae Zone [personal observations of one of us (J.A. Moreno-Bedmar); cf. Cantú-Chapa, 1989; Moreno-Bedmar et al., 2013]. It was found ex-situ in a section that can be attributed to the Dufrenoyia justinae Zone.

Dimensions (in mm): see Table 8.

Table 8: Measurements of Heminautilus aff. lallierianus (Orbigny, 1841).

D H E H/D E/D E/H M M/D M/H P L P/L L/H
no. IGM 10050 146.8 93.9 47.6 0.64 0.32 0.51 c7.8 0.05 0.08 27.1 61.8 0.44 0.66
- 68.3 30 - - 0.44 7.4 - 0.11 20.9 49.5 0.42 0.72
- 53.3 - - - - - - - 16.7 39.9 0.42 0.75
no. MPL1 180.0 95.0 - - - - - - - - - - -
- 96.0 - - - - - - - 18.0 59.0 0.31 0.61
- 67.0 - - - - - - - 19.0 53.0 0.36 0.79

Description: Heminautilus aff. lallierianus (Orbigny, 1841) has a relatively compressed section, with rounded flanks, of maximum thickness close to the umbilical edge. The ventral region is narrow, clearly concave and lined with two angular ventro-lateral edges. No ornamentation is visible in the specimen no. IGM 10050; in the specimen no. MPL1 some broad and strongly rursiradiate ribs are observable on the top of the flanks at the end of the body chamber. Heminautilus aff. lallierianus (Orbigny) can reach a large size (D = 180 mm in specimen no. MPL1, Pl. XL , fig. 1).

The suture line is very sinuous (Fig. 14 ), with a rounded and well developed lateral saddle and a deep lateral lobe (P/L between 0.31 and 0.44). The ventral lobe is well defined and angular in shape. The position of the siphuncle is not visible.

Fig. 14
Click on thumbnail to enlarge the image.

Figure 14: Heminautilus aff. lallierianus (Orbigny, 1841). Suture line of specimen no. IGM 10050, left side.

Discussion and comparisons: Heminautilus aff. lallierianus (Orbigny, 1841) is very close to H. lallierianus (Orbigny) and can be distinguished from it only by a slightly wider lateral saddle and a ventral region which is less concave. However, its stratigraphical position is clearly higher, in the Dufrenoyia justinae Zone (= top of the Dufrenoyia furcata Zone, Moreno-Bedmar et al., 2012, 2015), while H. lallierianus (Orbigny) is known only in the Deshayesites forbesi Zone, Roloboceras hambrovi Subzone. This unusual stratigraphical position, as well as its very distant geographical distribution, makes its incorporation into Orbigny's species uncertain, with additional data on specimens of intermediate stratigraphical position needed.

H. aff. lallierianus (Orbigny) can be easily distinguished from the other American species of the genus, H. etheringtoni Durham, 1946, and H. stantoni (Scott, 1940). It differs from H. etheringtoni Durham by its narrower section and ventral region, from H. stantoni (Scott, 1940) by the absence of ribbing on the phragmocone, and from both taxa by its clearly more concave ventral region and its different suture line, with a deep lateral lobe and a well developed lateral saddle.

Heminautilus etheringtoni Durham, 1946

Pl. XXX , fig. 3; Pl. XXXII , fig. 2; Pl. XLII , fig. 1; 
Pl. XLIII
, fig. 1; Pl. XLIV , figs. 1-2; Pl. XLV , figs. 1-2

1946

Heminautilus etheringtoni nov. sp. - Durham, p. 432, Pl. 62, fig. 4; Pl. 63, figs. 3, 5-7; Pl. 64, figs. 1-3.

1947

Heminautilus etheringtoni Durham, 1946 - Durham, p. 576, Figs. 1-3.

1979

Heminautilus etheringtoni Durham, 1946 - Etayo-Serna, p. 104, Pl. 4, fig. 8; Pl. 5, fig. 9.

?

2008

Heminautilus etheringtoni Durham, 1946 - Vega et al., Fig. 3c.

Material studied (N = 4): specimens no. M3, 124, coll. UNCB, Early Aptian, Quebrada el Cobre, Payandé, Tolima department (Colombia); no. UN-DG-NT-001, coll. UNCB, Early Aptian, Firavitoba, Boyacá department (Colombia); no. MB RE1962a, Early Aptian, Tibú Formation, Seboruco section, east of Mérida (Venezuela).

Type: the holotype (by original designation) is specimen no. 35731 (coll. MPUC) shown in Durham (1946: Pl. 62, fig. 4; Pl. 63, fig. 6; Pl. 64, fig. 3), stored in the collections of the Museum of Paleontology, University of California. It comes from locality A of Durham (1946), situated between El Valle and Payandé in Tolima department (Colombia) and is depicted anew in this work Pl. XLII , fig. 1; Pl. XLIII , fig. 1.

Geographical distribution: the species is known in Colombia and Venezuela.

Stratigraphical distribution: according to Durham, 1946, the holotype comes from locality A, associated with representatives of the genus Cheloniceras Hyatt, 1903. It is consequently possible to attribute it a stratigraphical position near the top of the Early Aptian. Also, specimen no. MB RE1962a comes from the Seboruco section (Venezuela) which, according to Renz (1982, p. 19), yielded ammonites of the genus Roloboceras Casey, 1954, but which more likely belong to the genus Cheloniceras Hyatt, 1903; its stratigraphical position is also near the top of the Early Aptian. Specimen no. F-15 (coll. MGNR) illustrated by Etayo-Serna (1979) comes from the uppermost part of the Early Aptian, Dufrenoyia sanctorum-Stoyanowiceras treffryanus Assemblage zone. The stratigraphical position of the specimens no. M3, 124 and UN-DG-NT-001 is not known.

Heminautilus etheringtoni Durham, 1946, is thus a species present at the top of the Early Aptian (= Dufrenoyia furcata Zone); its presence at a lower stratigraphical level in the Early Aptian is possible but remains hypothetical with the data in our possession.

Dimensions (in mm): see Table 9.

Table 9: Measurements of Heminautilus etheringtoni Durham, 1946.

  D H E H/D E/D E/H M M/D M/H P L P/L L/H
Holotype no. 35731 153 86 77 0.56 0.5 0.9 32 0.21 0.37 - - - -
116 65 - 0.56 - - - - - 17 45 0.38 0.69
- 53 59 - - 1.11 - - - 12 38 0.32 0.72
no. 124 105 - - - - - - - - - - - -
- 50.2 - - - - - - - 9.2 33.2 0.28 0.66
- 32 - - - - - - - 5.8 23.2 0.25 0.73
no. M3 80 - - - - - - - - - - - -
- 48.9 - - - - - - - 6.6 33.1 0.2 0.68
- 42.2 - - - - - - - 8.3 32.3 0.26 0.77
 no. UN-DG-NT-001 154 - - - - - - - - - - - -
- 72.3 - - - - - - - 15.3 53.8 0.28 0.74
- 65.1 - - - - - - - 13.6 49.5 0.27 0.76
no. 35733 (Durham, 1946) 53 31 25 0.58 0.47 0.81 - - - - - - -
- - - - - - - - - 3.5 12 0.29 -
no. F-15 (Etayo-Serna, 1979) 115 75 52 0.65 0.45 0.69 14 0.12 0.19 - - - -
- - - - - - - - - 6 20 0.30 -
no. MB RE1962a - 78 49 - - 0.63 18 - 0.23 - - - -
- 60 - - - - 14 - 0.23 12 53 0.23 0.88

Description: specimens illustrated by Durham (1946) show a fairly compressed section in the internal whorls, which widens through its ontogeny, particularly on the adult body chamber (holotype no. 35731, Pl. XLIII , fig. 1; specimen no. MB RE1962a, Pl. XXXII , fig. 2). The flanks, rounded in the internal whorls, quickly become flat and convergent towards the ventral region, with maximum thickness situated near the umbilical edge. The ventral region is fairly wide and rounded in the internal whorls; it widens and becomes gradually flat with a relatively angular ventro-lateral edge on the body chamber.

The ornamentation is formed by ribs and growth lines. Ribs, rounded, wide and weak, are present on the top of the flanks of the holotype's body chamber, where the shell is preserved. They are convex and become gradually strongly rursiradiate near the ventral region. Growth lines are visible on the ventral region; they are weak and form an angular sinus.

The suture line is fairly sinuous (Fig. 15 ), with a very wide and relatively deep lateral lobe (P/L between 0.32 and 0.38 in the holotype). The ventral lobe is shallow. The siphuncle is placed near the dorsal edge of the section [specimen no. M3 (coll. UNCB), Pl. XLIV , fig. 2; no. 124 (coll. UNCB), Pl. XLV , fig. 2].

Fig. 15
Click on thumbnail to enlarge the image.

Figure 15: Heminautilus etheringtoni Durham, 1946. Suture line of specimens no. 35731, right side (a-b) and 35733, left side (c).

Discussion and comparisons: Heminautilus etheringtoni Durham, 1946, presents affinities with H. ? tyosiensis (Yabe & Osaki, 1953), a species with a comparable shape of the body chamber section, associated with a wide ventral region, ornamented by growth lines forming an angular sinus. However, H. ? tyosiensis (Yabe & Osaki) can be distinguished by its clearly more concave ventral region and its different ribbing, well defined on the phragmocone and absent on the body chamber. Its suture line is also different, with a more developed lateral saddle and a clearly deeper lateral lobe [P/L between 0.40 and 0.50 in H. ? tyosiensis (Yabe & Osaki)].

H. etheringtoni Durham is also rather close to H. saxbii (Morris, 1848), particularly in its similar ornamentation and suture line, but can be distinguished by its section and its much wider ventral region, as well as by a much more rounded ventro-lateral shoulder, especially on the phragmocone.

H. etheringtoni Durham can also be compared to Josanautilus lacerdae (Vilanova, 1870) by its section and the form of its ventral region, but it can readily be distinguished from it by the absence of a median keel and of longitudinal ornamentation on the ventral region.

Heminautilus stantoni (Scott, 1940)

Pl. XXXVI , figs. 2-3

1940

Vorticoceras stantoni nov. sp. - Scott, p. 1076, Pl. 68, figs. 4-5.

Type: the holotype (by original designation) is specimen no. USNM103260, shown in Scott (1940) Pl. 68, figs. 4-5, stored in the collections of the United States National Museum, Washington, and coming from the locality M15 (Scott, 1940, p. 988), near Murfreesboro, Arkansas (USA). It is depicted anew in this work in Pl. XXXVI , fig. 3. A plaster cast of it (no. 35688, coll. BEG) is also shown in Pl. XXXVI , fig. 2.

Geographical distribution: the species is known only by its holotype, coming from Arkansas (USA).

Stratigraphical distribution: the holotype comes from the Dierks Limestone, Trinity Group of Arkansas. Scott (1940) indicates in this formation the presence of representatives of the genus Pseudosaynella Spath, 1923. In Mexico and in the south of the USA, the genus Pseudosaynella Spath appears to occupy a restricted stratigraphical position, limited to the uppermost part of the Early Aptian (Scott, 1940, p. 976; Moreno-Bedmar et al., 2015). Furthermore, Imlay (1945) reported the presence of the genus Pseudosaynella Spath, associated with Dufrenoyia Kilian & Reboul, 1915, at the top of the Pine Island Shale (lateral equivalent in Louisiana of the Dierks Limestone). These observations allow us to attribute to Heminautilus stantoni (Scott, 1940) a stratigraphical position at the top of the Early Aptian, confidently placed in the Dufrenoyia justinae Zone (= top of the Dufrenoyia furcata Zone, Moreno-Bedmar et al., 2012, 2013, 2015).

Dimensions (in mm): see Table 10.

Table 10: Measurements of Heminautilus stantoni (Scott, 1940).

  D H E H/D E/D E/H M M/D M/H P L P/L L/H
Holotype no. 1162 114 69 40 0.61 0.35 0.58 - - - 16 51 0.31 0.74
98 60 - 0.61 - - - - - 13 43 0.3 0.72

Description: the holotype no. USNM103260 consists of an incomplete phragmocone. It shows a fairly compressed section, with flanks clearly convex and bulging in their lower half and otherwise flat, converging to the ventral region. The ventral region is fairly wide and seems slightly concave, lined with two well defined shoulders.

The ornamentation is formed of spaced, wide, rursiradiate and rounded ribs, becoming higher and thus more visible in the upper half of the flanks.

The suture line (Fig. 16 ) is sinuous, with a wide and rounded lateral saddle, a well developed, fairly deep lateral lobe (P/L close to 0.30) and a narrow and well defined ventral lobe. The position of the siphuncle is not known.

Fig. 16
Click on thumbnail to enlarge the image.

Figure 16: Heminautilus stantoni (Scott, 1940). Suture line of specimen no. USNM103260, left side.

Discussion and comparisons: Heminautilus stantoni (Scott, 1940) is relatively close to H. saxbii (Morris, 1848) in its section, the shape of its ventral region and its suture line. H. stantoni (Scott) can be distinguished from H. saxbii (Morris) by its ribbing, consisting of very wide ribs and present on the phragmocone, which is only visible on the body chamber in H. saxbii (Morris). Its suture line also contains a lateral saddle more developed than the one of H. saxbii (Morris).

Heminautilus stantoni (Scott) also shows some affinities with H. lallierianus (Orbigny, 1841), in particular in the presence of a well developed lateral saddle. It differs, however, from H. lallierianus (Orbigny) in the presence of well defined ribbing on the phragmocone, a clearly shallower lateral lobe and a less concave ventral region.

Heminautilus stantoni (Scott) can be distinguished immediately from other species of the genus Heminautilus Spath, 1927, by its section, the shape of the ribbing and the presence of ribbing on the phragmocone.

Heminautilus ? japonicus sp. nov.

Pl. XXXVIII , fig. 2; Pl. XLIX , fig. 2; Pl. L , fig. 3

1976

Heminautilus lallierianus (Orbigny, 1841) - Obata & Ogawa, p. 103, Fig. 7a-c; Pl. 2, fig. 3.

1984

Heminautilus cf. H. lallierianus (Orbigny, 1841) - Obata et al., p. 30, Fig. 3; Pl. 5, fig. 1a-b; Pl. 6, fig. 1.

Holotype: specimen no. SH-1 (coll. E. Shimizu), illustrated by Obata et al. (1984) and depicted anew here in Pl. XLIX , fig. 2 and Pl. L , fig. 3. A cast is deposited in the National Science Museum in Tokyo, Japan under the no. NSM-PM 9381.

Origin of the name: the name comes from Japan, the origin of the holotype.

Type locality: according to Obata et al. (1984), the holotype comes from locality 203 of the sector of Sanchu, Kwanto Moutains (Gunma Prefecture, Japan).

Type strata: the presence, in the horizon where the holotype comes from, of Phylloceras sp., Barremites aff. strettostoma (Uhlig, 1883), Pseudohaploceras japonicum Obata et al., 1984, and Heteroceras aff. astierianum Orbigny, 1851, allows us to attribute Heminautilus ? japonicus sp. nov. to the latest Barremian (= Imerites giraudi Zone).

Geographical distribution: this taxon is known only in Japan. The holotype no. SH-1 comes from the Kwanto Moutains (Gunma Prefecture) and the specimen studied by Obata & Ogawa (1976) comes from the north of Yuasa-machi (Wakayama Prefecture) (Fig. 17 ).

Fig. 17
Click on thumbnail to enlarge the image.

Figure 17: Geographical position of specimens of Heminautilus ? japonicus sp. nov. and Heminautilus ? tyosiensis (Yabe & Osaki, 1953) referred to in the text.

Stratigraphical distribution: the holotype is dated from the latest Barremian (= Imerites giraudi Zone). The specimen illustrated by Obata & Ogawa (1976) as Heminautilus lallierianus (Orbigny, 1841) comes from the Arida Formation, whose uppermost part delivered Heteroceras aff. astieri Orbigny, 1851. It is contemporary with specimens attributed to Anahamulina cf. subcylindrica (Orbigny, 1850) (Obata & Ogawa, 1976, Pl. 4, figs. 9a-b, 10) but which are probably fragmentary representatives of Heteroceras Orbigny, 1849. Consequently this specimen comes certainly from the uppermost part of the Late Barremian (= Imerites giraudi Zone?). The species is only known with certainty in the latest Barremian (= Imerites giraudi Zone).

Dimensions (in mm): see Table 11.

Table 11: Measurements of Heminautilus ? japonicus sp. nov.

  D H E H/D E/D E/H M M/D M/H P L P/L L/H
Holotype no. SH-1 74.4 42.3 32 0.57 0.43 0.76 7 0.09 0.17 - - - -
- 46 - - - - - - - 14 39 0.36 0.85
Unregistered specimen (Obata & Ogawa, 1976) 106 69 45 0.65 0.42 0.65 17 0.16 0.25 - - - -
77 55 - 0.71 - - 14 0.18 0.25 20 45 0.44 0.82

Diagnosis: species of small size, relatively compressed, with rounded flanks, concave ventral region, ornamented with fine growth lines in chevron. Ornamentation absent or formed by fine rursiradiate ribs, only present on the top of the flanks of the body chamber. Suture line very sinuous, with a wide, deep and asymmetrical lateral lobe and a clear ventral lobe.

Description: Heminautilus ? japonicus sp. nov. is small-sized, with a fairly wide section and rounded flanks, of maximum thickness near the umbilical edge. The ventral region is narrow to fairly wide, clearly concave, with an angular ventro-lateral edge. It is ornamented with fine growth lines, which form an angular sinus. On the phragmocone, no ornamentation is visible on the flanks. On the body chamber, the holotype no. SH-1 shows an ornamentation formed by fine rursiradiate ribs, tight and only visible on the top of the flanks (Pl. L , fig. 3). No ornamentation seems to be present on the flanks of the specimen shown by Obata & Ogawa (1976).

The suture line is strongly sinuous (Fig. 18 ), with a very wide, deep and asymmetrical lateral lobe (P/L close to 0.40), and a very narrow and rounded lateral saddle. The ventral lobe is well defined and angular.

Fig. 18
Click on thumbnail to enlarge the image.

Figure 18: Heminautilus ? japonicus sp. nov. Suture line of the unregistered specimen, right side (a) illustrated by Obata & Ogawa (1976) and of specimen no. SH-1, left side (b).

The position of the siphuncle is not known.

Discussion and comparisons: Heminautilus ? japonicus sp. nov. is close to H. ? tyosiensis (Yabe & Osaki, 1953), possessing a similar suture line and a ventral region ornamented with fine growth lines. H. ? tyosiensis (Yabe & Osaki) can however be distinguished by its much wider ventral region, as well as the presence of a well defined ribbing on the flanks of the phragmocone. The stratigraphical position of H. ? tyosiensis (Yabe & Osaki) is also different, at the top of the Early Aptian (= Dufrenoyia furcata Zone).

Heminautilus ? japonicus sp. nov. is also relatively close to H. rangei (Hoppe, 1922), having a similar shape and ornamentation of its ventral region. Relationships between both species were analyzed in the section concerning H. rangei (Hoppe); the similarities observed could indicate a phyletic link between these taxa.

Heminautilus ? japonicus sp. nov. also presents some affinities with H. lallierianus (Orbigny, 1841), with in particular its concave ventral area, but can be distinguished from it easily by its small size, the ornamentation of its ventral area, its rounded flanks, its distinct suture line and its clearly older stratigraphical position.

As in H. ? tyosiensis (Yabe & Osaki), the plan of the suture line of H. ? japonicus sp. nov., relatively different from that of the other representatives of the genus Heminautilus Spath, 1927, could be compared to the one of the genus Xenocheilus Shimansky & Erlanger, 1955. The important stratigraphical gap as well as the misunderstanding of the position of the siphuncle in H. ? japonicus sp. nov. do not allow us to retain this hypothesis. For these reasons the attribution to the genus Heminautilus Spath, 1927, remains conditional.

Heminautilus ? tyosiensis (Yabe & Osaki, 1953)

Pl. XXXIII , fig. 2; Pl. XXXIV , figs. 2-3; Pl. XXXV , fig. 3

1953

Platynautilus tyôsiensis nov. sp. - Yabe & Osaki, p. 57, Pl. 1, figs. 1-4.

1975

Heminautilus tyosiensis (Yabe & Osaki, 1953) - Obata et al., p. 28, Pl. 2, fig. 2; Pl. 4, fig. 4.

1975

Heminautilus aff. tyosiensis (Yabe & Osaki, 1953) - Obata et al., p. 28, Pl. 4, fig. 2.

Type: the holotype (by original designation) is the specimen no. NMNS P1-4200 illustrated by Yabe & Osaki (1953), Pl. 1, figs. 1-4. It comes from the Tokawa quarry (Tyôsi Peninsula, Tiba Prefecture) and is stored in the National Science Museum in Tokyo, Japan. It is depicted anew in this work in Pl. XXXIII , fig. 2.

Geographical distribution: the species is known only in Japan, in the Choshi Peninsula (Chiba Prefecture) (Fig. 17 ).

Stratigraphical distribution: the holotype comes from the Inubouzaki Formation, dated doubtfully by Yabe & Osaki (1953) as Aptian. However, Obata & Matsukawa (2009) indicate for this formation the presence of the genera Australiceras Whitehouse, 1926, Tropaeum J. de C. Sowerby, 1837, Cheloniceras Hyatt, 1903, Dufrenoyia Kilian & Reboul, 1915, and Colombiceras Spath, 1923, which allows us to attribute it without ambiguity to the top of the Early Aptian (= Dufrenoyia furcata Zone). According to these authors, specimens illustrated by Obata et al. (1975) come from the Kimihagama Formation [likely equivalent to the major part of the Kimihagama, Inubouzaki and Toriakeura formations in the sense of Obata & Matsukawa (2009)], above the Ashikajima Formation [with Dufrenoyia aff. dufrenoyi (Orbigny, 1841)] and below the Nagasakihana Formation [with Cheloniceras meyendorffi (Orbigny, 1845)]; these specimens can thus be attributed also to the top of the Early Aptian (= Dufrenoyia furcata Zone).

In the absence of figures and of bibliographical reference, the presence of Heminautilus ? tyosiensis (Yabe & Osaki, 1953) indicated by Obata et al. (1982, p. 148) and by Obata & Matsukawa (2009, p. 254) in the Ashikajima Formation (in the sense of Obata & Matsukawa (2009), not Obata et al. (1975); Early Barremian) cannot be confirmed.

Heminautilus ? tyosiensis (Yabe & Osaki) is thus known with certainty only from the top of the Early Aptian.

Dimensions (in mm): see Table 12.

Table 12: Measurements of Heminautilus ? tyosiensis (Yabe & Osaki, 1953).

  D H E H/D E/D E/H M M/D M/H P L P/L L/H
Holotype no. NMNS P1-4200 70 43 20 0.61 0.29 0.47 18 0.26 0.42 - - - -
- 36 - - - - - - - 11 28 0.39 0.78
- 26 - - - - - - - 11 22 0.5 0.85

Description: the holotype (Pl. XXXIII , fig. 2) is a specimen of rather small size, preserved as a partially complete phragmocone with the major part of the body chamber. It shows a rather wide section, of maximum thickness near the umbilical edge, with a very involute coiling. Flanks are almost flat and converge on the ventral region. The ventral region is wide, slightly concave, surrounded by two angular edges; it shows in its median part a clear furrow.

On the adapical part of the phragmocone, four wide, weak and flexuous ribs are visible only on the outside part of the flanks. This ribbing quickly fades and then no ornamentation is visible on the flanks of the adoral part of the phragmocone and the body chamber. On the ventral region, the only discernible ornamentation consists of weak growth lines strongly retroverse and forming an angular chevron at the level of the median furrow.

The suture line, very sinuous (Fig. 19 ), shows a well developed lateral saddle and an asymmetrical, wide and deep lateral lobe, with a ratio P/L between 0.40 and 0.50. The depth of the lateral lobe decreases through ontogeny. The delineation of the suture line on the ventral region is not visible. The position of the siphuncle is unknown.

Fig. 19
Click on thumbnail to enlarge the image.

Figure 19: Heminautilus ? tyosiensis (Yabe & Osaki, 1953). Suture line of specimen no. NMNS P1-4200, right side.

The specimens no. NMNS PM6858 and no. NMNS PM6859 are very fragmentary, and show characteristics identical to those observable in the holotype. The specimen no. NMNS PM6858 (Pl. XXXIV , fig. 2; Pl. XXXV , fig. 3) corresponds to a body chamber; we observe in particular, on the ventral region, the characteristic ornamentation visible in the holotype, constituted by fine growth lines forming an angular chevron. The specimen no. NMNS PM6859 (Pl. XXXV , fig. 3) is constituted by a fragment of a small-sized whorl (young specimen or fragment of inner whorls of an adult specimen). Flanks show an ornamentation formed by wide and radial ribs, flexuous, similar to the ones visible on the phragmocone of the holotype.

Discussion and comparisons: Heminautilus ? tyosiensis (Yabe & Osaki, 1953) is close to Heminautilus ? japonicus sp. nov. The differences between both taxa were previously commented in the section of discussion and comparisons of H. ? japonicus sp. nov.

The very particular characteristics of Heminautilus ? tyosiensis (Yabe & Osaki) (the width of the ventral region and the presence of growth lines in the same part of the nautiloid) distinguish it from most of the other taxa of the genus Heminautilus Spath, 1927. Furthermore, the general shape of the shell and the plan of its suture line, with an asymmetrical lateral lobe and a wide and rounded lateral saddle, could also move this taxon closer to the genus Xenocheilus Shimansky & Erlanger, 1955, in particular to the species Xenocheilus ulixis Shimansky & Erlanger, 1955, from the Hauterivian of Crimea. The stratigraphical gap as well as the unknown position of the siphuncle in Heminautilus ? tyosiensis (Yabe & Osaki) make it difficult to attribute this species with certainty to the genus Heminautilus Spath.

Heminautilus etheringtoni Durham, 1946, shows, however, a comparable ventral region, but can be distinguished by a clearly more rounded ventro-lateral edge, as well as the absence of a median furrow and lateral ornamentation on the phragmocone. The plan of the suture line is also different, with a more reduced lateral saddle and a clearly shallower lateral lobe in H. etheringtoni Durham.

Heminautilus rangei (Hoppe, 1922) also presents some affinities with Heminautilus ? tyosiensis (Yabe & Osaki), in particular the presence of a rather similar ribbing on the phragmocone and of the ventro-lateral edges well defined on the body chamber. H. ? tyosiensis (Yabe & Osaki) can be distinguished from it easily by a greater thickness and by the absence of ribbing on the body chamber.

Genus Josanautilus Martínez & Grauges, 2006

Type species: Nautilus lacerdae Vilanova, 1870 (by original designation of Martínez & Grauges, 2006, p. 17).

Discussion: the genus is monospecific. Its stratigraphic distribution is very restricted, limited to the Early Aptian, upper part of the Deshayesites forbesi Zone (Roloboceras hambrovi Subzone). It is known only from France and Spain.

Josanautilus lacerdae (Vilanova, 1870)

Pl. XXXIX , figs. 2-3; Pl. XLI , figs. 2-3; Pl. XLII , fig. 2; 
Pl. XLIII
, fig. 2; Pl. XLVI , figs. 1-3; Pl. XLVII , figs. 1-2; 
Pl. XLVIII
, figs. 1-3; Pl. XLIX , fig. 1; 
Pl. L
, fig. 1; Pl. LI , fig. 1

1870

Nautilus lacerdae sp. nov. - Vilanova, Pl. 3, fig. 3.

1950

Nautilus lacerdae Vilanova, 1870 - Bataller, p. 64, Fig. 653.

1960

Carinonautilus ? lacerdae (Vilanova, 1870) - Wiedmann, p. 194, Fig. 24.

2006

Josanautilus lacerdae (Vilanova, 1870) - Martínez & Grauges, p. 18, Figs. 3a, 4b-e, 6b-c, 7c.

?

2007

Nautilus cf. lacerdae Vilanova, 1870 - Conte, p. 10, photos 8- 9.

Material studied (N = 15): specimens no. tl074, coll. Baudouin, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Le Teil (Ardèche, France); no. VI011, coll. Boselli, no. CH01, coll. Baudouin, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Viviers (Ardèche, France); no. MHNG GEPI 83570, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Groumaud section, Bourg-Saint-Andéol (Ardèche, France); no. A-148, JM-35, PUAB 48003, PUAB 48057, PUAB 48082, PUAB 48086, PUAB 48178, PUAB 48222, PUAB 48276, PUAB 48302, coll. PUAB, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain); no. Se-11.1, coll. MV, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Mas Segura, Province of Castellon (Spain).

Type: the holotype (by monotypy) is the specimen no. MNCN I-14855, coll. of the Museo Nacional de Ciencias Naturales (Madrid), drawn by Vilanova (1870) and photographed by Martínez & Grauges (2006). It comes from the Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone of Josa (Province of Teruel, Spain). The figure of Martínez & Grauges (2006) is reproduced here Pl. XLII , fig. 2.

Geographical distribution: Josanautilus lacerdae (Vilanova, 1870) is known only from France and Spain.

Stratigraphical distribution: according to Moreno et al. (2007), the species Josanautilus lacerdae (Vilanova, 1870) is present in the sector of Oliete and Josa, in the Margas del Forcall Formation, dated from the Roloboceras hambrovi Subzone by its plentiful fauna. It is likely that the holotype as well as paratypes studied by Martínez & Grauges (2006) come from this formation. Specimens no. tl074, VI011, CH01 and MHNG GEPI 83570 also come from the Roloboceras hambrovi Subzone. Thus, Josanautilus lacerdae (Vilanova) seems restricted to the upper part of the Deshayesites forbesi Zone (Roloboceras hambrovi Subzone).

Dimensions (in mm): see Table 13.

Table 13: Measurements of Josanautilus lacerdae (Vilanova, 1870).

  D H E H/D E/D E/H M M/D M/H P L P/L L/H
Holotype no. MNCN I-14855 126 75 56 0.6 0.44 0.75 - - - - - - -
109 71 - 0.65 - - - - - 22 49 0.45 0.69
93 57 - 0.61 - - - - - 20 42 0.48 0.74
no. tl074 c167 106 72 0.63 0.43 0.68 c28 0.17 0.26 - - - -
- 80 46 - - - 19 - 0.24 - - - -
no. MHNG GEPI 83570 c167 99 c65 0.59 0.39 0.66 - - - - - - -
- 91 - - - - 26 - 0.29 - - - -
- 75 - - - - 23 - 0.31 16 61 0.26 0.81
no. VI011 148 95 72 0.64 0.49 0.76 31 0.21 0.33 - - - -
98 62 43 0.63 0.44 0.69 c13 0.13 0.21 - - - -
no. CH01 156 110 92 0.71 0.59 0.84 - - - - - - -
no. A-148 87 57 41 0.66 0.47 0.72              
58.8 31.5 35.6 0.53 0.61 1.13 12.6 0.21 0.40 8.6 22.5 0.38 0.72
47.4 26.5 28.3 0.56 0.6 1.07 11.1 0.23 0.42 8.1 20.5 0.4 0.77
no. JM-35 - - - - - - - - - - - - -
no. PUAB 48003 c155 c96 c70 0.62 0.45 0.73              
- 59.3 40.2 - - 0.68 22.0 - 0.37 16.6 37.7 0.44 0.64
no. PUAB 48057 - - - - - - - - - - - - -
no. PUAB 48082 c165 98 c84 0.59 0.51 0.86 - - - - - - -
no. PUAB 48086 - c57 53 - - 0.93              
- 45.2 47.1 - - 1.04 18.7 - 0.41 11.6 31.2 0.37 0.69
no. PUAB 48178 c165 c100 - 0.61 - -              
135 88 57.3 0.65 0.42 0.65              
- 80.8 58.3 - - 0.72 27.4 - 0.34 16.9 50.5 0.33 0.63
- 67.9 54.2 - - 0.8 18.2 - 0.27 17.6 43.9 0.4 0.65
no. PUAB 48222 103 72.0 c48 0.7 0.47 0.67 - - - - - - -
- 57.3 47.7 - - 0.83 - - - 14.4 36.0 0.4 0.63
no. PUAB 48276 88 56 c46 0.64 0.52 0.82              
- 35.3 42.3 - - 1.2 14.3 - 0.41 7.4 23.9 0.31 0.68
no. PUAB 48302 78 53 c38 0.68 0.49 0.72              
74.7 42.8 40.3 0.57 0.54 0.94 15.0 0.20 0.35 11.8 30.0 0.39 0.7
52.5 30.0 27.7 0.57 0.53 0.92 10.1 0.19 0.34 8.0 22.1 0.36 0.74

Description: the various studied specimens show a very involute coiling, with a wide trapezoidal section, whose maximum thickness is located near the umbilical edge. Flanks are flat, convergent towards a relatively wide ventral region.

In the internal whorls the ventral region is rounded, with a weak median keel, and becomes gradually flat through ontogeny, with rounded ventro-lateral edge. On the adoral part of the phragmocone and on the body chamber, the ventral region widens and the ventral ornamentation strengthens: the median keel becomes strong, with round relief, lined with longitudinal ribs which appear gradually, but always remain weaker than the median keel. One or two longitudinal ribs are observable on each side of the keel at the beginning of the body chamber, up to three on each side at the end of the body chamber (specimen no. Se-11.1, Pl. XLVI , fig. 2).

Lateral ornamentation is almost absent: we observe only, as in some species of the genus Heminautilus Spath, 1927, the appearance of convex and rursiradiate ribs at the end of the body chamber, especially visible in the upper half of the flanks (specimen no. Se-11.1, Pl. XLVIII fig. 3).

The suture line (Fig. 20 ) shows a well developed, rounded lateral saddle, and a wide lateral lobe of rather variable depth, with P/L between 0.26 and 0.48. It crosses the ventral region almost straight, without forming a ventral lobe. The siphuncle, whose position was unknown until now, is visible on the specimen no. CH01 (Pl. XLVII fig. 2): it is placed near the dorsal region, at approximately 1/3 of the height of the section.

Fig. 20
Click on thumbnail to enlarge the image.

Figure 20: Josanautilus lacerdae (Vilanova, 1870). Suture line of specimen no. MNCN I-14855, left side (a-b), PUAB 48222, right side (c) and A-148, left side (d).

Discussion and comparisons: the particular characteristics of Josanautilus lacerdae (Vilanova, 1870) distinguish it immediately from most of the representatives of the genus Heminautilus Spath, 1927.

J. lacerdae (Vilanova) can, however, be compared to the slightly older (Late Barremian, Imerites giraudi Zone, to Early Aptian, Deshayesites forbesi Zone) species Heminautilus sanctaecrucis Conte, 1980, which also shows a ventral keel, the same type of ribbing only present at the end of the body chamber, and a suture line which shows a comparable delineation. J. lacerdae (Vilanova) can be distinguished from H. sanctaecrucis Conte by its section and its much wider ventral region, its stronger and rounded ventral keel, and by the presence of longitudinal ribs on the ventral region of the body chamber.

The wide section of J. lacerdae (Vilanova) is also comparable to that observed in the species H. ? tyosiensis (Yabe & Osaki, 1953) and H. etheringtoni Durham, 1946, but can be distinguished from them easily by the absence of longitudinal ornamentation in the latter two.

Josanautilus aff. lacerdae (Vilanova, 1870)

Pl. L , fig. 2; Pl. LI , fig. 2

Material studied (N = 1): specimen no. VI010, coll. Boselli, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Viviers (Ardèche, France).

Dimensions (in mm): see Table 14.

Table 14: Measurements of Josanautilus aff. lacerdae (Vilanova, 1870).

  D H E H/D E/D E/H M M/D M/H P L P/L L/H
no. VI010 146 95 83 0.65 0.57 0.87 27 0.18 0.28 - - - -
90 62 50 0.69 0.56 0.81 23 0.26 0.37 17 46 0.37 0.74
81 54 43 0.67 0.53 0.8 15 0.19 0.28 13 39 0.33 0.72

Description: adult specimen, badly preserved. The section is trapezoidal, relatively wide in the phragmocone, then widens very strongly in the body chamber. Flanks are flat or slightly convex, convergent towards the ventral region.

On the visible part of the phragmocone, the ventral region is fairly wide, flat, with a poorly defined median keel. On the body chamber, it strongly widens, where two longitudinal ribs gradually appear on each side of the median keel. On the last part of the body chamber, the longitudinal ribs and the median keel have the same strength.

No ornamentation can be seen on the major part of the flanks. On the second half of the body chamber, rursiradiate ribs appear, only visible near the ventral region.

The suture line (Fig. 21 ) shows a wide and rounded lateral saddle and a well developed and relatively deep lateral lobe (P/L between 0.33 and 0.37). There is no ventral lobe.

Fig. 21
Click on thumbnail to enlarge the image.

Figure 21: Josanautilus aff. lacerdae (Vilanova, 1870). Suture line of specimen no. VI010, left side.

Discussion and comparisons: Josanautilus aff. lacerdae (Vilanova, 1870) is very close to J. lacerdae (Vilanova), but differs from it by its weaker median keel, of the same strength as the longitudinal ribs which frame it, as well as by its particularly wide section. It is not however excluded that these characteristics could represent only one slightly atypical morph of J. lacerdae (Vilanova).

J. aff. lacerdae (Vilanova) also shows some superficial resemblance with the Berriasian species Aulaconautilus sexcarinatus (F.-J. Pictet, 1867), but can be distinguished from it by the characteristics explained in the section II. 2.: a very different section, a higher expansion rate of whorls, the presence of a median keel on the ventral region, the presence of ribbing at the end of the body chamber and a suture line with a different plan.

IV. Phylogenetic relationships within the genera Heminautilus Spath, 1927, and Josanautilus Martínez & Grauges, 2006

1. Heminautilus boselliorum Delanoy et al., 2012

At present, H. boselliorum Delanoy et al. is the oldest known species of the genus Heminautilus Spath, 1927, and is present in the Early Barremian, upper part of Kotetishvilia nicklesi Zone to lower part of Kotetishvilia compressissima Zone. As explained in the section II. 1., its origin must probably be related to the genus Pseudocenoceras Spath, 1927, and in particular to the taxon Pseudocenoceras campichei (Karakasch, 1907), from the Hauterivian? However, the evolutionary relationship between these genera requires more data and for this reason remains to be developed.

2. Heminautilus rangei (Hoppe, 1922)

The characteristics observed in H. rangei (Hoppe) allow us to envisage an origin from the taxon H. boselliorum Delanoy et al., 2012 (Fig. 22 ): a comparable section; a similar ventral region, flat or slightly concave with the possible presence of a weak median keel; an identical suture line, with a lateral lobe of comparable depth (P/L most of the time between 0.25 and 0.30). Only a slightly wider section and especially the early appearance of characteristic ribbing clearly differentiate the species H. rangei (Hoppe) from H. boselliorum Delanoy et al. The very early appearance of the ribbing could be interpreted in this case as the result of a peramorphic process of acceleration. However, the stratigraphical gap between both taxa is large [Early Barremian, Kotetishvilia nicklesi, Nicklesia pulchella and Kotetishvilia compressissima zones for H. boselliorum Delanoy et al., Late Barremian, Gerhardtia sartousiana or Imerites giraudi zones for H. rangei (Hoppe)]; with the absence of stratigraphically intermediate specimens, this hypothesis needs to be confirmed.

Fig. 22
Click on thumbnail to enlarge the image.

Figure 22: Phylogenetic relationships between the various species of the genera Heminautilus Spath, 1927, and Josanautilus Martínez & Grauges, 2006. In blue, species present only in the Tethyan Domain; in green, species present only in the North-Atlantic Domain; in red, species present only in Japan. Extinction event 1 represents the extinction of the genera Heminautilus Spath and Josanautilus Martínez & Grauges in the Tethyan Domain whereas extinction event 2 represents the global extinction of the genus Heminautilus Spath. Explanations in text.

3. Heminautilus sanctaecrucis Conte, 1980

As H. rangei (Hoppe, 1922), H. sanctaecrucis Conte presents very numerous similarities with H. boselliorum Delanoy et al., 2012, in particular a similar suture line, an identical section with a ventral region of the same profile and the same type of ribbing present only at the adoral end of the body chamber of the adult specimens. All these characteristics lead us to envisage a direct filiation (Fig. 22 ) between H. boselliorum Delanoy et al. and H. sanctaecrucis Conte, the major evolutionary trend being the development of a well defined ventral keel. Here too, the stratigraphical gap between both species is important [Early Barremian, Kotetishvilia nicklesi Zone to Kotetishvilia compressissima Zone for H. boselliorum Delanoy et al.; Late Barremian, Imerites giraudi Zone to Early Aptian, Deshayesites forbesi Zone for H. sanctaecrucis Conte]. The presence of H. aff. sanctaecrucis Conte in the Gerhardtia sartousiana Zone (specimen no. 415951, Pl. XII , fig. 4), whose characteristics seem intermediate between H. boselliorum Delanoy et al. and H. sanctaecrucis Conte, confirms this hypothesis.

4. Heminautilus saxbii (Morris, 1848)

H. saxbii (Morris) replaces H. sanctaecrucis Conte, 1980, in the Early Aptian, Deshayesites forbesi Zone and seems to descend directly from it (Fig. 22 ), essentially by disappearance of the typical ventral keel of H. sanctaecrucis Conte, development of a suture line with a slightly deeper lateral lobe [P/L generally between 0.20 and 0.35 for H. sanctaecrucis Conte and between 0.30 and 0.40 for H. saxbii (Morris)] and a more premature appearance of the ribbing on the adult body chamber.

H. saxbii (Morris) has also affinities with H. boselliorum Delanoy et al., 2012, but the very large stratigraphical gap between these species does not allow us to retain the hypothesis of a direct phyletic relation.

5. Heminautilus lallierianus (Orbigny, 1841)

As explained in part II, H. lallierianus (Orbigny) is a species very close to H. saxbii (Morris, 1848), and both taxa were considered as synonyms in numerous works. In reality, it seems that both species never coexisted; we think that H. lallierianus (Orbigny) represents a species different from H. saxbii (Morris) that in Europe, seems to have a slightly upper stratigraphical position in the Deshayesites forbesi Zone, Roloboceras hambrovi Subzone. These data support that H. lallierianus (Orbigny) descends directly from H. saxbii (Morris) (Fig. 22 ), with the appearance of a more concave ventral region and the development of a more sinuous suture line (wider and rounded lateral saddle, clearly deeper lateral and ventral lobes).

6. Heminautilus etheringtoni Durham, 1946, and Heminautilus stantoni (Scott, 1940)

The presence of H. aff. lallierianus (Orbigny, 1841) in Mexico (specimen no. IGM 10050, Pl. XXXIX , fig. 1 and specimen no. MPL1, Pl. XL , fig. 1), in the Dufrenoyia justinae Zone (= top of the Dufrenoyia furcata Zone), shows that the genus Heminautilus Spath, 1927, was present in Europe from the Early Barremian to the Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, but later during the latest Early Aptian the species H. lallierianus (Orbigny) probably migrated to America (cf. section V). H. lallierianus (Orbigny) is thus probably the ancestor (Fig. 22 ) of the species H. etheringtoni Durham and H. stantoni (Scott), known in Colombia, Venezuela and Arkansas (USA) in the uppermost part of the Early Aptian. The morphological differences with H. lallierianus (Orbigny) are relatively important: the appearance of a convex ventral region and a wider section in H. etheringtoni Durham, the development of a strong ribbing on the phragmocone in H. stantoni (Scott), and less sinuous suture lines in these two species. Furthermore, H. etheringtoni Durham and H. stantoni (Scott) also presents numerous similarities with H. saxbii (Morris, 1848) and an origin from this last species cannot be ruled out. In South America, Central America and southern North America, the genus Heminautilus Spath, 1927, is only represented by some isolated specimens of often poorly known stratigraphical position; the evolution of the group in this paleogeographic domain remains uncertain.

7. Heminautilus ? japonicus sp. nov.

This new species is known only by two specimens, coming from the Late Barremian of Japan (= Imerites giraudi Zone). Its origin is difficult to specify:

8. Heminautilus ? tyosiensis (Yabe & Osaki, 1953)

H. ? tyosiensis (Yabe & Osaki) is only represented by the four specimens illustrated by Yabe & Osaki, 1953, and Obata et al., 1975 (three of them shown here: Pl. XXXIII , fig. 2; Pl. XXXIV , figs. 2-3; Pl. XXXV, fig. 3), all coming from the uppermost part of the Early Aptian (= Dufrenoyia furcata Zone) from the Choshi Peninsula (Chiba Prefecture, Japan). This species is very close to Heminautilus ? japonicus sp. nov. from the Late Barremian of Japan and shows a similar sutural plan and the same ornamentation on the ventral region, formed by growth lines arranged in a chevron. H. ? tyosiensis (Yabe & Osaki) probably descended from Heminautilus ? japonicus sp. nov. (Fig. 22 ), with the appearance of a much wider ventral region and a ribbing well defined on the phragmocone.

9. Josanautilus lacerdae (Vilanova, 1870)

The characteristics of J. lacerdae (Vilanova), from the Deshayesites forbesi Zone, Roloboceras hambrovi Subzone of Spain and France, are very close to those of the genus Heminautilus Spath, 1927, and were discussed in the section II. 2. Josanautilus Martínez & Grauges, 2006, probably had its origin from Heminautilus sanctaecrucis Conte, 1980 (Fig. 22 ). These species follow one another in the Deshayesites forbesi Zone and have numerous common characteristics, in particular the presence of a ventral median keel; the main morphological change is the appearance in J. lacerdae (Vilanova) of a wider section and a clearly different ventral region (wider and on which longitudinal ribs are added to the median keel on the body chamber).

V. Stratigraphical and paleogeographical distribution

As mentionned above, the oldest representatives of the genus Heminautilus Spath, 1927, whose stratigraphical positions are exactly known belong to the species H. boselliorum Delanoy et al., 2012, from the Early Barremian, Kotetishvilia nicklesi, Nicklesia pulchella and Kotetishvilia compressissima zones. In Europe, North Africa and Japan, the genus is known at intervals up to the Early Aptian. In particular, no specimens are known with certainty from the uppermost part of the Early Barremian or the lowermost part of the Late Barremian, in the Moutoniceras moutonianum and Toxancyloceras vandenheckii zones. The genus presents its acme in the Early Aptian, Deshayesites forbesi Zone, with the species H. sanctaecrucis Conte, 1980, H. saxbii (Morris, 1848) and H. lallierianus (Orbigny, 1841), particularly frequent in Spain, France and England (Isle of Wight; Simpson, written communication, 2013). No younger specimens are known with certainty from Europe and North Africa. In the uppermost part of the Early Aptian, the genus seems to have migrated outside the Tethyan Domain (Fig. 23 ). Indeed, the taxa H. aff. lallierianus (Orbigny, 1841), H. etheringtoni Durham, 1946, H. stantoni (Scott, 1940) and H. ? tyosiensis (Yabe & Osaki, 1953) are known only from the uppermost part of the Early Aptian of Mexico, Colombia, Venezuela, USA (Arkansas) and Japan, respectively.

Fig. 23
Click on thumbnail to enlarge the image.

Figure 23: Geographical distribution of the various species of the genus Heminautilus Spath, 1927 (paleogeographical map of the Aptian from Klinger & Kennedy, 1977, modified). In red, distribution of the genus Heminautilus Spath during the Early Barremian; in blue, distribution of the genus Heminautilus Spath during the Late Barremian; in green, distribution of the genera Heminautilus Spath and Josanautilus Martínez & Grauges, 2006, during the early Early Aptian (Deshayesites oglanlensis and Deshayesites forbesi zones); in yellow, distribution of the genus Heminautilus Spath during the late Early Aptian (Dufrenoyia furcata Zone).

With the exception of the Japanese specimens, the stratigraphical and paleogeographical distribution of the genus Heminautilus Spath (Fig. 23 ) can be split into two clearly different phases:

The Japanese specimens studied here, belonging to the species Heminautilus ? japonicus sp. nov. and H. ? tyosiensis (Yabe & Osaki, 1953) are present in the Late Barremian (= Imerites giraudi Zone) and the Early Aptian (= Dufrenoyia furcata Zone), perhaps even in the Early Barremian (Obata et al., 1982, p. 148; Obata & Matsukawa, 2009, p. 254). The Japanese species seem to correspond to a local radiation of the group in a different domain (Pacific Domain; Ogg et al., 2012, p. 793) with a particular migration pattern and an endemic species evolution that remains poorly known. However, the particular morphology of this group does not allow excluding an origin in Xenocheilus Shimansky & Erlanger, 1955 (cf. section IV. 7.), which, if it were proved true by new data, could involve the restoration of the genus Platynautilus Yabe & Ozaki, 1953 (type species Platynautilus tyosiensis Yabe & Osaki, 1953), for these species.

The genera Heminautilus Spath and Josanautilus Martínez & Grauges seem to have particular ecological requirements and to be generally present only in the outer platform domain. They are nearly absent in deeper marine environments, for example in the Vocontian Basin (southeast France) or the Subbetic Domain (Spain), where other genera like Cymatoceras Hyatt, 1884, are nevertheless present. Heminautilus Spath and Josanautilus Martínez & Grauges are also frequently associated with ammonoids that are also characteristic of an outer platform environment:

As previously explained about the genus Angulithes Montfort, 1808 (Frank, 2010), the frequent appearance of ribbing on the body chamber or near the peristome can be interpreted as a strengthening of the shell, representing an adaptation to an environment of relatively high energy.

VI. Conclusions

The study of more than 160 specimens of the genera Heminautilus Spath, 1927, and Josanautilus Martínez & Grauges, 2006, allows us to identify more exactly the specific and stratigraphical characteristics of the various taxa of these two genera. In particular, this study demonstrates accurately the validity of the species H. saxbii (Morris, 1848) and H. lallierianus (Orbigny, 1841), and shows that H. tejeriensis Martínez & Grauges, 2006, is a junior synonym of H. saxbii (Morris), of which it represents a slightly atypical morph. As well, some specimens filled, at least partially, important gaps in the knowledge of the genus Heminautilus Spath, whose stratigraphical distribution is very intermittent between the Early Barremian and the upper part of the Early Aptian, as well as showing that the genus Heminautilus Spath was present from the Early Barremian, Kotetishvilia nicklesi Zone.

This work also highlights the existence of an important migration of the genus Heminautilus Spath, 1927, during the Early Aptian. Indeed, with the exception of the Japanese specimens (belonging to a group with particular morphology and attributed with doubt to the genus Heminautilus Spath), the genus seems to be only present in the Tethyan Domain (Europe and Africa) up to the uppermost part of the Deshayesites forbesi Zone, and later, it is absent in this domain, but it is present in the North-Atlantic Domain (Colombia, Venezuela, Mexico and the USA). Due to this paleogeographic migration and successive disappearances and appearances, we define two successive extinction events (Fig. 22 ).

It was also possible to formulate hypotheses about the origin and the phylogenetic and paleogeographic evolution of these two genera. In particular, the proposal of Tintant (Tintant & Kabamba, 1983; Tintant, 1993), who suggested the origin of Heminautilus Spath from Pseudocenoceras Spath, 1927, seems the most likely with the current data. However, the incomplete knowledge of the genus Heminautilus Spath, in particular during the Barremian, does not allow confirmation of this hypothesis. New specimens will be necessary for confirmation, in particular in the stratigraphical levels where the genus is unknown, in the middle part of the Barremian (Moutoniceras moutonianum and Toxancyloceras vandenheckii zones in particular), but also in the Early Aptian, between the uppermost part of the Deshayesites forbesi Zone and the uppermost part of the Early Aptian (= Dufrenoyia furcata Zone).

Acknowledgements

For their help and photos of numerous specimens, we warmly thank Masaki Matsukawa (Tokyo Gakugei University, Japan), Yasunari Shigeta (National Museum of Nature and Science, Japan), Haruyoshi Maeda (Kyushu University Museum, Japan), Mark B. Goodwin (Museum of Paleontology, University of California, Berkeley, USA), Thomas Jorstad (United States National Museum, Washington, USA), Pedro C.R. Patarroyo Gama (Universidad Nacional de Colombia), Steve Donovan (Nationaal Natuurhistorisch Museum, Leiden, Netherlands), Ramadan Abu-Zied (King Abdulaziz University, Saudi Arabia), Jens Lehmann (Faculty of Geosciences, Bremen University, Germany), Jesús Quiroz Barragán (Director of the Museo Paleontológico de la Laguna, Torreón, Coahuila State, Mexico), Gilles Pavy (Muséum d'Histoire Naturelle of Auxerre, France), Marin Ivanov and Vyara Idakieva (Sofia University, Bulgaria), István Főzy (Department of Paleontology and Geology, Hungarian Natural History Museum), Frank Bach (Geologisch-paläontologischen Institut, Leipzig University, Germany), Martin Simpson (Isle of Wight, England), Jean-Louis Latil (Lazer, France), Camille Frau (La Ciotat, France), Loic Villiers and Axel Arnoux (Aix-Marseille University, France), Dominique Gesbert and Daniel Frasali. We also thank Didier Merle, Jean-Michel Pacaud and Sylvain Charbonnier (Muséum National d'Histoire Naturelle of Paris, France) for their welcome and their help during our investigations in the Orbigny collection, Isabelle Rouget (Pierre et Marie Curie University, Paris, France) for examination of the collections of the Sorbonne University, and Emmanuel Robert (co-director of the geological collections, Lyon 1 University, France) for his welcome during our visit to the collection of the École des Mines stored in the Claude Bernard University. We warmly thank our reviewers Marcela Cichowolski (Buenos Aires University, Argentina) and Miguel Company (Granada University, Spain) for their constructive remarks, and Stephen P. Carey (Federation University, University of Ballarat, Australia) for the improvement of the English text. Part of this study was supported by grant PAPIIT IA104715 from DGAPA, Universidad Nacional Autónoma de México.

Bibliographic references

Abu-Zied R.H. (2008).- Lithostratigraphy and biostratigraphy of some Lower Cretaceous outcrops from Northern Sinai, Egypt.- Cretaceous Research, 29, p. 603-624.

Aly M.F. (2006).- Aptian cephalopods from Gabal Abu Ruqum, north Sinai, Egypt.- Egyptian Journal of Paleontology, Cairo, 6, p. 89-123 (7 Pls.).

Amédro F. & Matrion B. (2004).- Les ammonites aptiennes des Argiles à Plicatules de la bordure orientale du bassin de Paris: un aperçu.- Bulletin de l'Association Géologique Auboise, Sainte-Savine, 24-25, p. 75-80 (1 Pl.).

Arnaud H. (2005).- The South-East France Basin (SFB) and its Mesozoic evolution. In: Adatte T., Arnaud-Vanneau A., Arnaud H., Blanc-Alétru M.C., Bodin S., Carrio-Schaffhauser E., Föllmi K.B., Godet A., Chaker Raddadi M. & Vermeulen J. (eds.), The Hauterivian-Lower Aptian sequence stratigraphy from Jura platform to vocontian basin: a multidisciplinary approach. Field-trip of the 7th International symposium on the Cretaceous (September 1-4, 2005).- Géologie alpine, Grenoble, (Série spéciale "Colloques et Excursions"), 7, p. 5-28.

Bataller J.R. (1950).- Sinopsis de las especies nuevas del Cretácico de España.- Anales de la Escuela de Peritos Agrícolas y de Especialidades Agropecuarias y de Servicios Técnicos de Agricultura, Barcelona, 9, p. 61-164.

Bert D., Delanoy G. & Bersac S. (2008).- Nouveaux biohorizons et propositions pour un nouveau découpage bio-zonal ammonitique, et nouveaux bio-horizons pour le Barrémien supérieur.- Carnets Geol., Madrid, vol. 8, no. A03 (CG2008_A03), 18 p.

Bosellini A., Russo A. & Schroeder R. (1999).- Stratigraphic evidence for an Early Aptian sea-level fluctuation: the Graua Limestone of south-eastern Ethiopia.- Cretaceous Research, 20, p. 783-791.

Bulot L.G., Latil J.-L., Vermeulen J. & Fouad Aly M. (2011).- Mogharaeceras priscum (Douvillé, 1916) a peculiar Barremian ammonite (Desmoceratoidea, Barremitinae) from Northern Sinai (Egypt).- Geologica Carpathica, Bratislava, 62, p. 575-578.

Cantú-Chapa A. (1989).- La Peña Formation (Aptian): a condensed limestone-shale sequence from the subsurface of NE Mexico.- Journal of Petroleum Geology, 12 (1), p. 69-84 (1 Pl.).

Casey R., Bayliss H.M. & Simpson M.I. (1998).- Observations on the lithostratigraphy and ammonite succession of the Aptian (Lower Cretaceous) Lower Greensand of Chale Bay, Isle of Wight, UK.- Cretaceous Research, 19, p. 511-535.

Chirat R. & Bucher H. (2006).- Shell microstructure and morphogenesis of the ornamentation in Cymatoceras Hyatt, 1883, Cretaceous Nautilida. Systematic implications.- Lethaia, 39, p. 57-64.

Conte G. (1980).- Heminautilus sanctaecrucis, nouvelle espèce de Nautiloïde crétacé.- Geobios, Villeurbanne, 13 (1), p. 137-141 (1 Pl.).

Conte G. (1985).- Le genre Heminautilus Spath, 1927 dans le Bédoulien (Aptien inférieur) de la région de la Bédoule (SE France).- Géologie Méditerranéenne, Marseille, XII/XIII, p. 29-35 (1 Pl.).

Conte G. (1989).- Fossiles du plateau d'Albion.- Les Alpes de Lumière, Forcalquier, 99, 75 p.

Conte G. (2007).- Présence du genre Heminautilus Spath, 1927 dans le Gard et l'Ardèche.- Bulletin de la Société d'Étude des Sciences naturelles de Nîmes et du Gard, 66, p. 9-15.

Conte G. (2010).- Fossiles peu connus découverts en Vaucluse.- Courrier scientifique du Parc naturel régional du Luberon, Apt, 9, p. 114-119.

Corroy G. (1925).- Le Néocomien de la bordure orientale du Bassin de Paris.- Thèse, Paris, Imprimerie J. Coubé et fils, 334 p. (11 Pls.).

Delanoy G., Baudouin C., Gonnet R., Conte G. & Frau C. (2012).- Sur la présence des genres Heminautilus Spath, 1927 et Eucymatoceras Spath, 1927 (Nautilida, Nautilaceae) dans le Barrémien inférieur du Gard (sud-est de la France).- Annales du Muséum d'Histoire naturelle de Nice, XXVII, p. 155-195 (13 Pls.).

Dimitrova N. (1967).- Les fossiles de Bulgarie, IV, Crétacé inférieur, Cephalopoda (Nautiloidea et Ammonoidea).- Académie Bulgare des Sciences, Sofia, 424 p. (93 Pls.).

Donovan S.K. & Baker S. (2003).- Fossils explained 44 - Post-Palaeozoic nautiloids.- Geology Today, 19 (5), p. 181-186.

Douvillé H. (1916).- Les terrains secondaires dans le massif du Moghara à l'est de l'isthme de Suez d'après les explorations de M. Couyat-Barthoux. Paléontologie.- Mémoire de l'Académie des Sciences de l'institut de France, 54 (2), 185 p. (21 Pls.).

Durham J.W. (1946).- Upper Aptian nautiloids from Colombia.- Journal of Paleontology, 20 (5), p. 428-434 (3 Pls.).

Durham J.W. (1947).- Nuclear whorls of Heminautilus etheringtoni Durham.- Journal of Paleontology, 21 (6), p. 576-577.

Dzik J. (1984).- Phylogeny of the Nautiloidea.- Palaeontologia Polonica, Warszawa, 45, 219 p. (47 Pls.).

Etayo-Serna F. (1979).- Zonation of the Cretaceous of central Colombia by ammonites.- Publicaciones Geológicas Especiales del Ingeominas, Bogotá, 2, 188 p. (15 Pls.).

Főzy I. & Janssen N. (2009).- Integrated Lower Cretaceous biostratigraphy of the Bersek Quarry, Gerecse Mountains, Transdanubian Range, Hungary.- Cretaceous Research, 30, p. 78-92.

Főzy I. & Szente I. (2013).- Fossils of the Carpathian region.- Life of the Past, Indiana University Press, Bloomington, 508 p.

Frank J. (2010).- Taxonomy and palaeoecology of Cretaceous nautilids Angulithes galea (Fritsch in Fritsch & Schlönbach, 1872) and Angulithes westphalicus (Schlüter, 1872).- Bulletin of Geosciences, Prague, 85 (3), p. 487-496.

Gómez-Alba J.A.S. (1988).- Guía de Campo de los fósiles de España y de Europa.- Ediciones Omega, Barcelona, 972 p. (237 Pls.).

Hoppe W. (1922).- Jura und Kreide der Sinaihalbinsel.- Zeitschrift des Deutschen Palästina-Vereins, Wiesbaden, 45, p. 61-79, 97-219 (4 Pls.).

Imlay R. (1945).- Ammonites from the Dierks Limestone of Southern Arkansas.- Journal of Paleontology, 19 (3), p. 277-281 (2 Pls.).

Karakasch N.I. (1907).- Le Crétacé inférieur de la Crimée et sa faune.- Travaux de la société impériale des naturalistes de St.-Pétersbourg, 32 (5), 482 p. (28 Pls.).

Klinger H.C. & Kennedy W.J. (1977).- Cretaceous faunas from Zululand, South Africa, and southern Mozambique, the Aptian Ancyloceratidae (Ammonoidea).- Annals of the South African Museum, Cape Town, 73 (9), p. 215-359.

Kummel B. (1956).- Post-Triassic nautiloid genera.- Bulletin of the Museum of comparative Zoology, Cambridge, Mass., 114 (7), p. 319-494 (28 Pls.).

Kummel B. (1964).- Nautiloidea-Nautilida. In: Moore R.C. (ed.), Treatise on Invertebrate Paleontology, part K, Mollusca 3.- Geological Society of America and University of Kansas Press, p. K383-466.

Lehmann J., Heldt M., Bachmann M. & Hedi Negra M.E. (2009).- Aptian (Lower Cretaceous) biostratigraphy and cephalopods from north central Tunisia.- Cretaceous Research, 30, p. 895-910.

Mahmoud I. (1955).- Études paléontologiques sur la faune crétacique du Massif du Moghara (Sinaï - Égypte).- Publications de l'Institut du Désert d'Égypte, Le Caire, 8, 192 p. (19 Pls.).

Marchand D. & Tintant H. (1971).- Études statistiques sur Pseudaganites aganiticus (Schloteim) et diverses espèces voisines.- Bulletin scientifique de Bourgogne, Dijon, 28, p. 111-170 (4 Pls.).

Martínez R. & Grauges A. (2006).- Nautílidos del Aptiense Inferior (Cretácico Inferior) de la Subcuenca de Oliete, Cordillera Ibérica oriental (Teruel, España).- Revista Española de Paleontología, Madrid, 21 (1), p. 15-27.

Masse J.-P. (1976).- Les calcaires urgoniens de Provence (Valanginien-Aptien inférieur). Stratigraphie, paléontologie, les paléoenvironnements et leur évolution.- Thèse Université Aix-Marseille-II, 445 p. (60 Pls.).

Masse J.-P. & Fenerci-Masse M. (2011).- Drowning discontinuities and stratigraphic correlation in platform carbonates. The late Barremian-early Aptian record of southeast France.- Cretaceous Research, 32, p. 659-684.

Matsumoto, T., Kanmera K. & Ohta Y. (1980).- Cephalopod faunule from the Cretaceous Yatsushiro Formation (Kyushu) and its implications.- Transactions and Proceedings of the Palaeontological Society of Japan, Tokyo, (N.S.), 118, p. 325-338 (1 Pl.).

Moreno J.A., Company M., Delanoy G., Grauges A., Martínez G. & Salas R. (2007).- Precisiones sobre la edad, mediante ammonoideos y nautiloideos, de la fm. Margas del Forcall en la subcuenca de Oliete (Cadena Ibérica, España).- Geogaceta, Madrid, 42, p. 75-78 (1 Pl.).

Moreno J.A., Martín-Closas C. & Salas R. (2008).- El registre fòssil marí (porífers, ammonítids, nautílids i equinoïdeus) i continental (caròfits) del cretaci inferior (barremià superior - aptià) del Garraf.- V Trobada d'Estudiosos del Garraf, Diputació de Barcelona, p. 205-211.

Moreno-Bedmar J.A., Barragán Manzo R., Company Sempere M. & Bulot L.G. (2013).- Aptian (Lower Cretaceous) ammonite biostratigraphy of the Francisco Zarco Dam stratigraphic section (Durango State, northeast Mexico).- Journal of South American Earth Sciences, 42, p. 150-158.

Moreno-Bedmar J.A., Bover-Arnal T., Barragán R. & Salas R. (2012).- Uppermost Lower Aptian transgressive records in Mexico and Spain: chronostratigraphic implications for the Tethyan sequences.- Terra Nova, 24, p. 333-338.

Moreno-Bedmar J.A., Company M., Bover-Arnal T., Salas R., Delanoy G., Martínez R., Grauges A. (2009).- Biostratigraphic characterization by means of ammonoids of the lower Aptian Oceanic Anoxic Event (OAE 1a) in the eastern Iberian Chain (Maestrat Basin, eastern Spain).- Cretaceous Research, 30, p. 864-872.

Moreno-Bedmar J.A., Mendoza-Rosales C., Minor K.P., Delanoy G., Barragán R. & González-León O. (2015).- Towards an Aptian (Lower Cretaceous) ammonite biostratigraphy of the Mina Texali section, Central Atlantic province (Puebla State, Central Mexico).- Cretaceous Research, 54, p. 203-211.

Morris J. (1848).- Description of a new species of Nautilus from the Lower Greensand of the Isle of Wight.- Annals and Magazine of Natural History, 1, p. 106-107.

Nikolov T. & Parashkevanov P. (1995).- Some fossil cephalopods from the Loveč Urgonian Group at the village of Puševo, Veliko Târnovo District (Lower Cretaceous, Central Fore-Balkan).- Geologica Balcanica, Sofia, 25 (1), p. 61-70 (10 Pls.).

Obata I., Hagiwara S. & Kamiko S. (1975).- Geological age of the Cretaceous Choshi Group.- Bulletin of the National Science Museum, Tokyo, (series C), 1 (1), p. 17-36 (4 Pls.).

Obata I. & Matsukawa M. (2009).- Supplementary description of the ammonoids from the Barremian to the Albian of the Choshi Peninsula, Japan.- Cretaceous Research, 30, p. 253-269.

Obata I., Maiya S., Inoue Y. & Matsukawa M. (1982).- Integrated Mega- and Micro-fossil Biostratigraphy of the Lower Cretaceous Choshi Group, Japan.- Bulletin of the National Science Museum, Tokyo, (series C), 8 (4), p. 145-179 (7 Pls.).

Obata I., Matsukawa M., Tanaka K., Kanai Y. & Watanabe T. (1984).- Cretaceous Cephalopods from the Sanchu Area, Japan.- Bulletin of the National Science Museum, Tokyo, (series C), 10 (1), p. 9-37 (6 Pls.).

Obata I. & Ogawa Y. (1976).- Ammonites Biostratigraphy of the Cretaceous Arida Formation, Wakayama Prefecture.- Bulletin of the National Science Museum, Tokyo, (series C), 2 (2), p. 93-110 (4 Pls.).

Ogg J.G., Hinnov L.A. & Huang C. (2012).- Chapter 27: Cretaceous. In: Gradstein F.M., Ogg J.G., Schmitz M. & Ogg G. (eds.), The geologic time scale 2012.- Elsevier B.V., Amsterdam, p. 793-853.

Orbigny A. d' (1841).- Description de quelques espèces de mollusques fossiles de France.- Revue zoologique par la Société Cuvierienne, Paris, p. 318-319.

Orbigny A. d' (1850).- Prodrome de paléontologie stratigraphique universelle des animaux mollusques et rayonnés.- Masson éd., Paris, 394 p.

Peropadre Medina C. (2011).- El Aptiense del margen occidental de la Cuenca del Maestrazgo: controles tectónico, eustático y climático en la sedimentación.- Thèse de doctorat, Departamento de Estratigrafía de la Universidad Complutente de Madrid & Instituto de Geociencias (CSIC-UCM), 649 p.

Pictet A., Delanoy G., Baudouin C. & Boselli P. (2009).- Le genre Lithancylus Casey, 1960 (Ammonoidea, Ancyloceratina) dans l'Aptien inférieur du Couloir rhodanien (Drôme, Sud-Est de la France).- Revue de Paléobiologie, Genève, 28 (2), p. 491-509 (4 Pls.).

Pictet A., Delanoy G., Adatte T., Spangenberg J. E., Baudouin C., Boselli P., Boselli M., Kindler P. & Föllmi K.B. (2015).- Three successive phases of platform demise during the early Aptian and their association with the oceanic anoxic Selli episode (Ardèche, France).- Palæogeography, Palæoclimatology, Palæoecology, 418, p. 101-125.

Pictet F.-J. & Campiche G. (1858-1860).- Description des fossiles du terrain Crétacé des environs de Sainte-Croix, première partie.- Matériaux pour la Paléontologie suisse, Genève, 380 p. (43 Pls.).

Range P. (1920).- Die Geologie der Isthmuswüste.- Zeitschrift der Deutschen Geologischen Gesellschaft, Stuttgart, 72, p. 233-242 (1 Pl.).

Reboulet S., Rawson P.F., Moreno-Bedmar J.A., Aguirre-Urreta M.B., Barragán R., Bogomolov Y., Company M., González-Arreola C., Idakieva Stoyanova V., Lukeneder A., Matrion B., Mitta V., Randrianaly H., Vašiček Z., Baraboshkin E.J., Bert D., Bersac S., Bogdanova T.N., Bulot L.G., Latil J.-L., Mikhailova I.A., Ropolo P. & Szives O. (2011).- Report on the 4th International Meeting of the IUGS Lower Cretaceous Ammonite Working Group, the "Kilian Group" (Dijon, France, 30th August 2010).- Cretaceous Research, 32, p. 786-793.

Reboulet S., Szives O., Aguirre-Urreta B., Barragán R., Company M., Idakieva V., Ivanov M., Kakabadze M.V., Moreno-Bedmar J.A., Sandoval J., Baraboshkin E.J., Çaglar M.K., Főzy I., González-Arreola C., Kenjo S., Lukeneder A., Raisossadat S.N., Rawson P.F. & Tavera J.M. (2014).- Report on the 5th International Meeting of the IUGS Lower Cretaceous Ammonite Working Group, the Kilian Group (Ankara, Turkey, 31st August 2013).- Cretaceous Research, 50, p. 126-137.

Renz O. (1982).- The Cretaceous ammonites of Venezuela.- Maraven Editor, Caracas, 132 p. (40 Pls.).

Schroeder R., Buchem F. van, Cherchi A., Baghbani D., Vincent B., Immenhauser A. & Granier B. (2010).- Revised orbitolinid biostratigraphic zonation for the Barremian - Aptian of the eastern Arabian Plate and implications for regional stratigraphic correlations.- GeoArabia Special Publication, Manama, 4 (1), p. 49-96.

Scott G. (1940).- Cephalopods from the Cretaceous Trinity group of the south-central United States.- The University of Texas Publication, Austin, no. 3945, p. 969-1106 (68 Pls.).

Scott G. (1943).- Palaeontology of Harrar Province, Ethiopia. Part 4. Jurassic Cephalopoda and a Cretaceous Nautilus.- Bulletin of the American Museum of Natural History, New York, 82 (3), p. 61-93 (Pls. 10-25).

Shimansky V.N. (1975).- Cretaceous Nautiloids.- Transactions of the Palaeontological Institute of the Academy of Sciences of the USSR, Moscow, 150, 208 p. (34 Pls.).

Simpson M.I. (1985).- The stratigraphy of the Atherfield Clay Formation (Lower Aptian; Lower Cretaceous) at the type and other localities in southern England.- Proceeding of the Geologists' Association, London, 96 (1), p. 23-45.

Skelton P.W., Spicer R.A., Kelley S.P. & Gilmour I. (2003).- The Cretaceous World.- Cambridge University Press, 360 p.

Spath L.F. (1927).- Revision of the Jurassic cephalopod fauna of Kachh (Cutch).- Memoirs of the Geological Survey of India, Paleontologia Indica, Lucknow, 9, 71 p. (7 Pls.).

Tintant H. (1980).- Un cas de parallélisme évolutif synchrone chez les Nautiles à côtes du Jurassique.- Boletim da Societa Geologica de Portugal, Lisboa, XII, p. 63-69 (2 Pls.).

Tintant H. (1989).- Les avatars ontogénétiques et phylogénétiques de l'ornementation chez les Nautiles post-triasiques.- Geobios, Villeurbanne, Mém. spéc. 12, p. 357-367.

Tintant H. (1993).- L'évolution itérative des Nautiles post-triasiques.- Geobios, Villeurbanne, Mém. spéc. 15, p. 359-372.

Tintant H. & Kabamba M. (1983).- Le Nautile, fossile vivant ou forme cryptogène ? Essai sur l'évolution et la classification des Nautilacés.- Bulletin de la Société zoologique de France, Paris, 108, p. 569-579.

Tintant H. & Kabamba M. (1985).- The role of environment in the evolution of Nautilacea. In: Bayer U. & Seilacher A. (eds.), Sedimentary and evolutionary cycles.- Springer Verlag, p. 58-66.

Vega F.-J., Feldmann R.M., Etayo-Serna F., Bermúdez-Aguirre H.D. & Gómez J. (2008).- Occurrence of Meyeria magna M'Coy, 1849 in Colombia: a widely distributed species during Aptian times.- Boletín de la Sociedad Geológica Mexicana, Ciudad de México, 60 (1), p. 1-10.

Vermeulen J. (2002).- Étude stratigraphique et paléontologique de la Famille des Pulchellidae (Ammonoidea, Ammonitina, Endemocerataceae).- Géologie Alpine, Grenoble, Mémoire Hors Série, 42, 333 p. (57 Pls.).

Vilanova J. (1870).- Ensayo de descripción geognóstica de la Provincia de Teruel en sus relaciones con la agricultura de la misma.- Junta General de Estadística, 1863 y 1868, 312 p. (1 Pl.).

Wiedmann J. (1960).- Zur systematik jungmesozoischer nautiliden.- Palaeontographica, Abt. A, Stuttgart, 115, p. 144-206 (Pls. 17-27).

Yabe H. & Ozaki H. (1953).- A new type of Cretaceous nautiloids from Tyosi Peninsula, Kwanto Region.- Bulletin of the National Sciences Museum, Tokyo, 32, p. 55-61 (1 Pl.).


Plates

Pl. 01
Click on thumbnail to enlarge the image.

Plate I

Fig. 1a-b: Xenocheilus ulixis Shimansky & Erlanger, 1955. Holotype no. 103/101, Early Hauterivian, Biassala (Crimea, Ukraine). Reproduction of the original illustration of Karakasch (1907; Nautilus malbosi F.-J. Pictet, Pl. I, fig. 12a-b).

Fig. 2a-b: Pseudocenoceras campichei (Karakasch, 1907). Holotype, Hauterivian?, Biassala (Crimea, Ukraine). Reproduction of the original illustration of Karakasch (1907; Pl. VIII, fig. 13a-b).

Pl. 02
Click on thumbnail to enlarge the image.

Plate II

Fig. 1a-b: Aulaconautilus sexcarinatus (F.-J. Pictet, 1867). Cast of the holotype no. MHNG GEPI 15856, Berriasian, Berrias (Ardèche, France). Coll. F.-J. Pictet.

Fig. 2a-b: "Heminautilus" akatsui Matsumoto, 1980. Holotype no. GK. H6909, Early Albian, Bishô (Kumamoto Prefecture, Japan).

Fig. 3a-b: Heminautilus boselliorum Delanoy et al., 2012. Holotype no. Mej01a, Early Barremian, Nicklesia pulchella Zone, la Lèque, Lussan (Gard, France). Coll. Baudouin.

Pl. 03
Click on thumbnail to enlarge the image.

Plate III

Fig. 1: Heminautilus boselliorum Delanoy et al., 2012. Holotype no. Mej01a, Early Barremian, Nicklesia pulchella Zone, la Lèque, Lussan (Gard, France). Coll. Baudouin.

Fig. 2a-c: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. MNHN.F.A52065, Early Barremian, Nicklesia pulchella Zone, la Lèque, Lussan (Gard, France). Coll. Frau.

Fig. 3a-c: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. Mej11, Early Barremian, Nicklesia pulchella Zone, la Lèque, Lussan (Gard, France). Coll. Baudouin.

Pl. 04
Click on thumbnail to enlarge the image.

Plate IV

Fig. 1a-b: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. Mej03, Early Barremian, Nicklesia pulchella Zone, la Lèque, Lussan (Gard, France). Coll. Baudouin.

Fig. 2: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. Mej02, Early Barremian, Nicklesia pulchella Zone, la Lèque, Lussan (Gard, France). Coll. Baudouin.

Fig. 3a-b: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. LUS02, Early Barremian, Nicklesia pulchella Zone, la Lèque, Lussan (Gard, France). Coll. Boselli.

Pl. 05
Click on thumbnail to enlarge the image.

Plate V

Fig. 1a-c: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. RG2001, Early Barremian, Nicklesia pulchella Zone, la Lèque, Lussan (Gard, France). Coll. Gonnet.

Fig. 2: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. LUS02, Early Barremian, Nicklesia pulchella Zone, la Lèque, Lussan (Gard, France). Coll. Boselli.

Pl. 06
Click on thumbnail to enlarge the image.

Plate VI

Fig. 1a-b: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. RG2002b, Early Barremian, Nicklesia pulchella Zone, la Lèque, Lussan (Gard, France). Coll. Gonnet.

Fig. 2: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. 415950, upper part of the Kotetishvilia nicklesi Zone, section no. 833, Comps-sur-Artuby (Var). Coll. Vermeulen.

Pl. 07
Click on thumbnail to enlarge the image.

Plate VII

Fig. 1a-b: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. LUS01, Early Barremian, Nicklesia pulchella Zone, la Lèque, Lussan (Gard, France). Coll. Boselli.

Fig. 2: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. MHNG GEPI 15935, Early Barremian, Nicklesia pulchella Zone?, Escragnolles (Alpes-Maritimes, France). Coll. F.-J. Pictet.

Fig. 3a-d: Heminautilus rangei (Hoppe, 1922). Specimen no. EM697, Late Barremian?, Bir Lagama, Gabal Maghara (north Sinai, Egypt).

Fig. 4a-b: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. 415950, upper part of the Kotetishvilia nicklesi Zone, section no. 833, Comps-sur-Artuby (Var). Coll. Vermeulen.

Pl. 08
Click on thumbnail to enlarge the image.

Plate VIII

Fig. 1: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. K1 1693, Early Barremian, Kara Mihal village (Šumen District, Bulgaria). Coll. MPUS.

Fig. 2a-c: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. K1 1694, Early Barremian, Kriva Reka village (Šumen District, Bulgaria). Coll. MPUS.

Fig. 3a-b: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. RG2002a, Early Barremian, Nicklesia pulchella Zone, la Lèque, Lussan (Gard, France). Coll. Gonnet.

Pl. 09
Click on thumbnail to enlarge the image.

Plate IX

Fig. 1: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. K1 1693, Early Barremian, Kara Mihal village (Šumen District, Bulgaria). Coll. MPUS.

Fig. 2a-c: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. M 2002.554, Early Barremian, Kotetishvilia compressissima Zone, Bersek quarry (Gerecse Mountains, Hungary). Coll. HNHM.

Fig. 3: Heminautilus boselliorum Delanoy et al., 2012. Specimen no. MHNG GEPI 15935, Early Barremian, Nicklesia pulchella Zone?, Escragnolles (Alpes-Maritimes, France). Coll. F.-J. Pictet.

Fig. 4a-c: Heminautilus rangei (Hoppe, 1922). Specimen no. EM696, Late Barremian?, Bir Lagama, Gabal Maghara (north Sinai, Egypt).

Fig. 5a-b: Heminautilus rangei (Hoppe, 1922). Specimen no. EM698, Late Barremian?, Bir Lagama, Gabal Maghara (north Sinai, Egypt).

Pl. 10
Click on thumbnail to enlarge the image.

Plate X

Fig. 1a-b: Heminautilus rangei (Hoppe, 1922). Neotype no. EM699, Late Barremian?, Bir Lagama, Gabal Maghara (north Sinai, Egypt).

Fig. 2: Heminautilus rangei (Hoppe, 1922). Specimen no. EM698, Late Barremian?, Bir Lagama (north Sinai, Egypt).

Fig. 3a-c: Heminautilus rangei (Hoppe, 1922). Specimen no. TK25-15, Late Barremian, El Tourkumanyia (north Sinai, Egypt). Coll. GMMU.

Pl. 11
Click on thumbnail to enlarge the image.

Plate XI

Fig. 1: Heminautilus rangei (Hoppe, 1922). Late Barremian?, "Ledschime", (north Sinai, Egypt). Reproduction of the original illustration of Hoppe (1922; Pl. 4, fig. 2).

Fig. 2: Heminautilus rangei (Hoppe, 1922). Late Barremian?, "Ledschime", (north Sinai, Egypt). Reproduction of the original illustration of Hoppe (1922; Pl. 4, fig. 3).

Fig. 3a-c: Heminautilus sanctaecrucis Conte, 1980. Holotype no. MCGL 20747, Early Aptian, Deshayesites forbesi Zone, Sainte-Croix (Switzerland). Coll. F.-J. Pictet.

Fig. 4: Heminautilus sanctaecrucis Conte, 1980. Specimen no. MHNG GEPI 15936, Early Aptian, Deshayesites forbesi Zone, La Presta, Val-de-Travers (Switzerland). Coll. F.-J. Pictet.

Fig. 5: Heminautilus sanctaecrucis Conte, 1980. Specimen no. 131H, latest Barremian/earliest Aptian, col des Abeilles, Monieux (Vaucluse, France). Coll. Gesbert.

Pl. 12
Click on thumbnail to enlarge the image.

Plate XII

Fig. 1: Heminautilus sanctaecrucis Conte, 1980. Specimen no. 131H, latest Barremian/earliest Aptian, col des Abeilles, Monieux (Vaucluse, France). Coll. Gesbert.

Fig. 2: Heminautilus sanctaecrucis Conte, 1980. Specimen no. Bw599, Late Barremian, Imerites giraudi Zone, Pseudocrioceras waagenoides Subzone, bed 78, Les Caniers, La Bédoule (Bouches du Rhône, France). Coll. Gonnet, FSM.

Fig. 3a-b: Heminautilus sanctaecrucis Conte, 1980. Specimen no. K1 6003, Late Barremian, nord of the Puševo village (Veliko Târnovo District, Bulgaria). Coll. MPUS.

Fig. 4a-b: Heminautilus aff. sanctaecrucis Conte, 1980. Specimen no. 415951, Late Barremian, Gerhardtia sartousiana Zone, base of the Hemihoplites feraudianus Subzone, bed 165/041, Angles (Alpes-de-Haute-Provence, France). Coll. Baudouin (donated by Vermeulen).

Pl. 13
Click on thumbnail to enlarge the image.

Plate XIII

Fig. 1a-b: Heminautilus sanctaecrucis Conte, 1980. Specimen no. Bw599, Late Barremian, Imerites giraudi Zone, Pseudocrioceras waagenoides Subzone, bed 78, Les Caniers, La Bédoule (Bouches du Rhône, France). Coll. Gonnet, FSM.

Fig. 2a-b: Heminautilus sanctaecrucis Conte, 1980. Specimen no. K1 1692, Late Barremian, Lipnica village (Veliko Târnovo District, Bulgaria). Coll. MPUS.

Fig. 3a-c: Heminautilus sanctaecrucis Conte, 1980. Specimen no. MHNN 26904, Early Aptian, Deshayesites forbesi Zone, La Presta, Val-de-Travers (Switzerland). Coll. Jacquart.

Pl. 14
Click on thumbnail to enlarge the image.

Plate XIV

Fig. 1a-b: Heminautilus sanctaecrucis Conte, 1980. Specimen no. K1 6001, Late Barremian, north of the Puševo village (Veliko Târnovo District, Bulgaria). Coll. MPUS.

Fig. 2a-b: Heminautilus sanctaecrucis Conte, 1980. Specimen no. K1 6002, Late Barremian, north of the Puševo village (Veliko Târnovo District, Bulgaria). Coll. MPUS.

Pl. 15
Click on thumbnail to enlarge the image.

Plate XV

Fig. 1a-b: Heminautilus sanctaecrucis Conte, 1980. Unregistered specimen, Early Aptian, Coustellet quarry (Vaucluse, France). Coll. Frasali.

Fig. 2a-b: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 88770, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Tolodella, Maestrat Basin (Spain).

Pl. 16
Click on thumbnail to enlarge the image.

Plate XVI

Fig. 1: Heminautilus sanctaecrucis Conte, 1980. Specimen no. K1 6001, Late Barremian, north of the Puševo village (Veliko Târnovo District, Bulgaria). Coll. MPUS.

Fig. 2a-b: Heminautilus saxbii (Morris, 1848). Holotype no. BMNH 47019, Early Aptian, Deshayesites forbesi Zone, Isle of Wight (England). Coll. Saxby.

Fig. 3a-b: Heminautilus saxbii (Morris, 1848). Specimen no. EM700, Early Aptian?, Bir Lagama, Gabal Maghara (Egypt).

Pl. 17
Click on thumbnail to enlarge the image.

Plate XVII

Fig. 1a-b: Heminautilus saxbii (Morris, 1848). Specimen no. EM700, Early Aptian?, Bir Lagama, Gabal Maghara (Egypt).

Fig. 2: Heminautilus saxbii (Morris, 1848). Specimen no. A-127, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Coll. PUAB.

Fig. 3a-b: Heminautilus saxbii (Morris, 1848). Specimen no. PMBb2, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Coll. Marin.

Pl. 18
Click on thumbnail to enlarge the image.

Plate XVIII

Fig. 1: Heminautilus saxbii (Morris, 1848). Specimen no. A-144, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Coll. PUAB.

Fig. 2a-b: Heminautilus saxbii (Morris, 1848). Specimen no. A-145, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Coll. PUAB.

Fig. 3a-b: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 88767, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Tolodella, Maestrat Basin (Spain).

Pl. 19
Click on thumbnail to enlarge the image.

Plate XIX

Fig. 1: Heminautilus saxbii (Morris, 1848). Specimen no. MV 428.3, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Mola Murada, Maestrat Basin (Spain).

Fig. 2: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 88762, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Lo Pui, Organyà Basin (Spain).

Fig. 3a-b: Heminautilus saxbii (Morris, 1848). Specimen no. JM-34, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Coll. PUAB.

Pl. 20
Click on thumbnail to enlarge the image.

Plate XX

Fig. 1a-b: Heminautilus saxbii (Morris, 1848). Specimen no. PNRL 1189, Early Aptian, Deshayesites forbesi Zone, Murs (Vaucluse, France). Coll. A. Pictet.

Fig. 2: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 89788, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Galve, Province of Teruel (Spain).

Fig. 3: Heminautilus saxbii (Morris, 1848). Specimen no. AG-3, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Coll. PUAB.

Pl. 21
Click on thumbnail to enlarge the image.

Plate XXI

Fig. 1: Heminautilus saxbii (Morris, 1848). Specimen no. MV 428.2, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Mola Murada, Maestrat Basin (Spain).

Fig. 2a-b: Heminautilus saxbii (Morris, 1848). Specimen no. PM3N11, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Coll. Marin.

Fig. 3: Heminautilus saxbii (Morris, 1848). Specimen no. PM1, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Coll. Marin.

Fig. 4: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 89788, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Galve, Province of Teruel (Spain).

Pl. 22
Click on thumbnail to enlarge the image.

Plate XXII

Fig. 1a-b: Heminautilus saxbii (Morris, 1848). Specimen no. PM13, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Coll. Marin.

Fig. 2: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 48013, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Fig. 3: Heminautilus saxbii (Morris, 1848). Specimen no. PM1, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Coll. Marin.

Pl. 23
Click on thumbnail to enlarge the image.

Plate XXIII

Fig. 1a-b: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 48042, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Fig. 2: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 48013, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Fig. 3: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 48158, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Fig. 4a-b: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 48255, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Pl. 24
Click on thumbnail to enlarge the image.

Plate XXIV

Fig. 1: Heminautilus saxbii (Morris, 1848). Specimen no. 12576, Early Aptian, "Provence" (France). Coll. FSM.

Fig. 2a-b: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 88373, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Cuchía, Basque Cantabrian Basin (Spain).

Fig. 3a-b: ? Heminautilus saxbii (Morris, 1848). Specimen no. MB RE1962A, Early Aptian, Tibú Formation, Seboruco section, east of Mérida (Venezuela).

Pl. 25
Click on thumbnail to enlarge the image.

Plate XXV

Fig. 1: Heminautilus saxbii (Morris, 1848). Specimen no. 12576, Early Aptian, "Provence" (France). Coll. FSM.

Fig. 2a-b: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 88372, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Cuchía, Basque Cantabrian Basin (Spain).

Fig. 3a-b: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 48261, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Fig. 4: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 48044 (paratype of Heminautilus tejeriensis Martínez & Grauges, 2006), Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Pl. 26
Click on thumbnail to enlarge the image.

Plate XXVI

Fig. 1a-b: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 48292 (holotype of Heminautilus tejeriensis Martínez & Grauges, 2006), Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Fig. 2: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 48044 (paratype of Heminautilus tejeriensis Martínez & Grauges, 2006), Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Fig. 3a-b: Heminautilus saxbii (Morris, 1848). Early Aptian, Josa, Province of Teruel (Spain). Holotype of Heminautilus verneuilli Vilanova, 1870, reproduction of the original illustration.

Pl. 27
Click on thumbnail to enlarge the image.

Plate XXVII

Fig. 1a-b: Heminautilus lallierianus (Orbigny, 1841). Specimen no. PUAB 89780, Early Aptian, probably Deshayesites forbesi Zone, El Vendrell, Garraf (Spain).

Fig. 2a-c: Heminautilus lallierianus (Orbigny, 1841). Specimen no. 85-3, Early Aptian, upper part of the Deshayesites forbesi Zone?, Gurgy (Yonne, France). Coll. MHNA.

Pl. 28
Click on thumbnail to enlarge the image.

Plate XXVIII

Fig. 1a-b: Heminautilus lallierianus (Orbigny, 1841). Specimen no. PM95, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Coll. Marin.

Fig. 2a-b: Heminautilus lallierianus (Orbigny, 1841). Specimen no. MGB 22607, Early Aptian, Garraf (Spain).

Fig. 3a-b: Heminautilus lallierianus (Orbigny, 1841). Specimen no. MPP.B-EM.69, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, banc no. 148, La Bédoule (Bouches du Rhône, France). Coll. Frau, FSM.

Pl. 29
Click on thumbnail to enlarge the image.

Plate XXIX

Fig. 1a-c: Heminautilus lallierianus (Orbigny, 1841). Lectotype no. MNHN.F.A32800, coll d'Orbigny (no. 5573), Early Aptian, upper part of the Deshayesites forbesi Zone?, Gurgy (Yonne, France). Coll. d'Orbigny.

Fig. 2: Heminautilus lallierianus (Orbigny, 1841). Specimen no. 77-543, Early Aptian, upper part of the Deshayesites forbesi Zone?, Gurgy (Yonne, France). Coll. MHNA.

Fig. 3a-b: Heminautilus lallierianus (Orbigny, 1841). Specimen no. tl028, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Le Teil (Ardèche, France). Coll. Baudouin.

Pl. 30
Click on thumbnail to enlarge the image.

Plate XXX

Fig. 1: Heminautilus lallierianus (Orbigny, 1841). Specimen no. 77-543, Early Aptian, upper part of the Deshayesites forbesi Zone?, Gurgy (Yonne, France). Coll. MHNA.

Fig. 2: Heminautilus lallierianus (Orbigny, 1841). Specimen no. tl056, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Le Teil (Ardèche, France). Coll. Baudouin.

Fig. 3a-c: Heminautilus etheringtoni Durham, 1946. Specimen no. 35733, upper part of the Early Aptian, locality A (Durham, 1946), Tolima department (Colombia). Coll. MPUC.

Pl. 31
Click on thumbnail to enlarge the image.

Plate XXXI

Fig. 1: Heminautilus lallierianus (Orbigny, 1841). Specimen no. tl056, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Le Teil (Ardèche, France). Coll. Baudouin

Fig. 2a-b: Heminautilus lallierianus (Orbigny, 1841). Specimen no. BRG103, upper part of the Deshayesites forbesi Zone, bed no. 12, Pierrelatte section (Drôme, France). Coll. Baudouin.

Fig. 3: Heminautilus saxbii (Morris, 1848). Specimen no. PUAB 48158, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Pl. 32
Click on thumbnail to enlarge the image.

Plate XXXII

Fig. 1: Heminautilus lallierianus (Orbigny, 1841). Specimen no. VI009, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Viviers (Ardèche, France). Coll. Boselli.

Fig. 2a-b: Heminautilus etheringtoni Durham, 1946. Specimen no. MB RE1962a, Early Aptian, Tibú Formation, Seboruco section, east of Mérida (Venezuela).

Pl. 33
Click on thumbnail to enlarge the image.

Plate XXXIII

Fig. 1a-b: Heminautilus lallierianus (Orbigny, 1841). Specimen no. tl069, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Le Teil (Ardèche, France). Coll. Baudouin.

Fig. 2a-c: Heminautilus ? tyosiensis (Yabe & Osaki, 1953). Holotype no. NMNS P1-4200, upper part of the Early Aptian (= Dufrenoyia furcata Zone), Tokawa quarry, Tyôsi Peninsula, Tiba Prefecture (Japan).

Pl. 34
Click on thumbnail to enlarge the image.

Plate XXXIV

Fig. 1: Heminautilus lallierianus (Orbigny, 1841). Specimen no. tl078, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Le Teil (Ardèche, France). Coll. Baudouin.

Fig. 2a-b: Heminautilus ? tyosiensis (Yabe & Osaki, 1953). Specimen no. NMNS PM6858, upper part of the Early Aptian (= Dufrenoyia furcata Zone), Tyôsi Peninsula, Tiba Prefecture (Japan).

Fig. 3a-c: Heminautilus ? tyosiensis (Yabe & Osaki, 1953). Specimen no. NMNS PM6859, upper part of the Early Aptian (= Dufrenoyia furcata Zone), Tyôsi Peninsula, Tiba Prefecture (Japan).

Pl. 35
Click on thumbnail to enlarge the image.

Plate XXXV

Fig. 1: Heminautilus lallierianus (Orbigny, 1841). Specimen no. tl029, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Le Teil (Ardèche, France). Coll. Baudouin.

Fig. 2: Heminautilus lallierianus (Orbigny, 1841). Specimen no. tl078, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Le Teil (Ardèche, France). Coll. Baudouin.

Fig. 3a-b: Heminautilus ? tyosiensis (Yabe & Osaki, 1953). Specimen no. NMNS PM6858, upper part of the Early Aptian (= Dufrenoyia furcata Zone), Tyôsi Peninsula, Tiba Prefecture (Japan).

Pl. 36
Click on thumbnail to enlarge the image.

Plate XXXVI

Fig. 1: Heminautilus lallierianus (Orbigny, 1841). Specimen no. tl029, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Le Teil (Ardèche, France). Coll. Baudouin.

Fig. 2a-b: Heminautilus stantoni (Scott, 1940). Plastotype no. 35688, uppermost part of the Early Aptian, probably Dufrenoyia justinae Zone, locality M15, near Murfreesboro (Arkansas, USA). Coll. BEG.

Fig. 3: Heminautilus stantoni (Scott, 1940). Holotype no. USNM103260, uppermost part of the Early Aptian, probably Dufrenoyia justinae Zone, locality M15, near Murfreesboro (Arkansas, USA).

Pl. 37
Click on thumbnail to enlarge the image.

Plate XXXVII

Fig. 1a-c: Heminautilus lallierianus (Orbigny, 1841). Specimen no. 12573, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, La Bédoule (Bouches du Rhône, France). Coll. FSM.

Pl. 38
Click on thumbnail to enlarge the image.

Plate XXXVIII

Fig. 1: Heminautilus lallierianus (Orbigny, 1841). Specimen no. 12572, Early Aptian, Hameau of Les Roux, Cuges-les-Pins (Bouches du Rhône, France). Coll. FSM.

Fig. 2a-c: Heminautilus ? japonicus sp. nov. Unregistered specimen, Late Barremian (= Imerites giraudi Zone?), north of Yuasa-machi, Wakayama Prefecture (Japan). Reproduction of the illustration of Obata & Ogawa (1976).

Pl. 39
Click on thumbnail to enlarge the image.

Plate XXXIX

Fig. 1: Heminautilus aff. lallierianus (Orbigny, 1841). Specimen no. IGM 10050, Early Aptian, Dufrenoyia justinae Zone, bed no. 15, Mina Texali, Santa Isabel Atenayuca, Puebla State (Mexico).

Fig. 2: Josanautilus lacerdae (Vilanova, 1870). Specimen no. PUAB 48057, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Fig. 3a-b: Josanautilus lacerdae (Vilanova, 1870). Specimen no. PUAB 48276, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Pl. 40
Click on thumbnail to enlarge the image.

Plate XL

Fig. 1a-b: Heminautilus aff. lallierianus (Orbigny, 1841). Specimen no. MPL1, Early Aptian, Dufrenoyia justinae Zone, Sierra del Rosario, Durango State (Mexico).

Fig. 2a-b: Heminautilus lallierianus (Orbigny, 1841). Specimen no. UPMC-250, Early Aptian, upper part of the Deshayesites forbesi Zone?, Gurgy (Yonne, France). Coll. Tombeck.

Pl. 41
Click on thumbnail to enlarge the image.

Plate XLI

Fig. 1: Heminautilus lallierianus (Orbigny, 1841). Specimen no. AMNH 25455, median part of the Early Aptian, Harrar region (Ethiopia). Reproduction of the illustration of Scott (1943).

Fig. 2: Josanautilus lacerdae (Vilanova, 1870). Specimen no. PUAB 48222, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Fig. 3a-b: Josanautilus lacerdae (Vilanova, 1870). Specimen no. PUAB 48302, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Pl. 42
Click on thumbnail to enlarge the image.

Plate XLII

Fig. 1: Heminautilus etheringtoni Durham, 1946. Holotype no. 35731, upper part of the Early Aptian, locality A (Durham, 1946), Tolima department (Colombia). Coll. MPUC.

Fig. 2a-b: Josanautilus lacerdae (Vilanova, 1870). Holotype no. MNCN I-14855, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Repoduction of the illustration of Martínez & Grauges (2006).

Pl. 43
Click on thumbnail to enlarge the image.

Plate XLIII

Fig. 1a-b: Heminautilus etheringtoni Durham, 1946. Holotype no. 35731, upper part of the Early Aptian, locality A (Durham, 1946), Tolima department (Colombia). Coll. MPUC.

Fig. 2a-b: Josanautilus lacerdae (Vilanova, 1870). Specimen no. PUAB 48178, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain).

Pl. 44
Click on thumbnail to enlarge the image.

Plate XLIV

Fig. 1: Heminautilus etheringtoni Durham, 1946. Specimen no. UN-DG-NT-001, Early Aptian, Firavitoba, Boyacá department (Colombia). Coll. UNCB.

Fig. 2a-c: Heminautilus etheringtoni Durham, 1946. Specimen no. M3, Early Aptian, Quebrada el Cobre, Payandé, Tolima department (Colombia). Coll. UNCB.

Pl. 45
Click on thumbnail to enlarge the image.

Plate XLV

Fig. 1: Heminautilus etheringtoni Durham, 1946. Specimen no. UN-DG-NT-001, Early Aptian, Firavitoba, Boyacá department (Colombia). Coll. UNCB.

Fig. 2a-b: Heminautilus etheringtoni Durham, 1946. Specimen no. 124, Early Aptian, Quebrada el Cobre, Payandé, Tolima department (Colombia). Coll. UNCB.

Pl. 46
Click on thumbnail to enlarge the image.

Plate XLVI

Fig. 1: Josanautilus lacerdae (Vilanova, 1870). Specimen no. VI011, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Viviers (Ardèche, France). Coll. Boselli.

Fig. 2: Josanautilus lacerdae (Vilanova, 1870). Specimen no. Se-11.1, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Mas Segura, Maestrat Basin (Spain). Coll. MV.

Fig. 3: Josanautilus lacerdae (Vilanova, 1870). Specimen no. A-148, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Josa, Province of Teruel (Spain). Coll. PUAB.

Pl. 47
Click on thumbnail to enlarge the image.

Plate XLVII

Fig. 1a-b: Josanautilus lacerdae (Vilanova, 1870). Specimen no. VI011, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Viviers (Ardèche, France). Coll. Boselli.

Fig. 2: Josanautilus lacerdae (Vilanova, 1870). Specimen no. CH01, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Viviers (Ardèche, France). Coll. Baudouin.

Pl. 48
Click on thumbnail to enlarge the image.

Plate XLVIII

Fig. 1: Josanautilus lacerdae (Vilanova, 1870). Specimen no. VI011, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Viviers (Ardèche, France). Coll. Boselli.

Fig. 2: Josanautilus lacerdae (Vilanova, 1870). Specimen no. CH01, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Viviers (Ardèche, France). Coll. Baudouin.

Fig. 3: Josanautilus lacerdae (Vilanova, 1870). Specimen no. Se-11.1, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Mas Segura, Maestrat Basin (Spain). Coll. MV.

Pl. 49
Click on thumbnail to enlarge the image.

Plate XLIX

Fig. 1a-b: Josanautilus lacerdae (Vilanova, 1870). Specimen no. tl074, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Le Teil (Ardèche, France). Coll. Baudouin.

Fig. 2a-b: Heminautilus ? japonicus sp. nov. Holotype no. SH-1, Late Barremian (= Imerites giraudi Zone?), locality 203, sector of Sanchu, Kwanto Moutains, Gunma Prefecture (Japan). Coll. E. Shimizu. Reproduction of the illustration of Obata et al. (1984).

Pl. 50
Click on thumbnail to enlarge the image.

Plate L

Fig. 1a-b: Josanautilus lacerdae (Vilanova, 1870). Specimen no. MHNG GEPI 83570, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Groumaud section, Bourg-Saint-Andéol (Ardèche, France). Coll. A. Pictet.

Fig. 2: Josanautilus aff. lacerdae (Vilanova, 1870). Specimen no. VI010, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Viviers (Ardèche, France). Coll. Boselli.

Fig. 3: Heminautilus ? japonicus sp. nov. Holotype no. SH-1, Late Barremian (= Imerites giraudi Zone?), locality 203, sector of Sanchu, Kwanto Moutains, Gunma Prefecture (Japan). Coll. E. Shimizu. Reproduction of the illustration of Obata et al. (1984).

 

Pl. 51
Click on thumbnail to enlarge the image.

Plate LI

Fig. 1: Josanautilus lacerdae (Vilanova, 1870). Specimen no. MHNG GEPI 83570, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Groumaud section, Bourg-Saint-Andéol (Ardèche, France). Coll. A. Pictet.

Fig. 2a-b: Josanautilus aff. lacerdae (Vilanova, 1870). Specimen no. VI010, Early Aptian, Deshayesites forbesi Zone, Roloboceras hambrovi Subzone, Viviers (Ardèche, France). Coll. Boselli.

Appendix

Appended table: List of and information on the specimens of Nautiloidea Blainville, 1825, studied, referred to or depicted.

Appendix
Click on thumbnail to enlarge the image.