Sous-embranchement (subphylum) des Rhynchonelliformea
Classe des Rhynchonellata
Ordre des Terebratulida
Sous-Ordre des Terebratellidina
Super-famille Uncertain


Genus Simplicithyris Zezina, 1976

[Type species= Simplicithyris kurilensis Zezina, 1976 (p. 101)]

Small, smooth, slightly biconvex, recti- marginate to slightly unisulcate; foramen permesothyrid, deltidial plates narrow; pedicle collar broad, dental plates strong; median septum subrectangular; no cardinal process, crura, brachial loop, or spicules. Differs from Amphithyris in possession of dental plates and permesothyrid foramen and from Pumilus in possession of dental plates, smooth inner surface, and lack of spicules.


Diagnosis from volume 6 of the Treatise on Invertebrate Paleontology (2007)

Extant Species of Simplicithyris
  • S. kurilensis Zezina, 1976
  • S. japonica (Dall, 1920)
  • Diagnosis

    Simplicithyris kurilensis  Zezina, 1976

    Type locality: Iturup Island, Kuril, at the depth 16 m (st. 218, sample 511, 1970).
    Depth range: 5 - 580 m

    Simplicithyris kurilensis Zezina, 1976, p. 102

    Diagnosis - Zezina (1976)

    in Russian

    from Zezina (1979)

    Simplicithyris japonica (Dall, 1920)

    Type locality: off Hondo (= Honshu), 119 m
    Depth range: 119 m

    Platidia japonica Dall, 1920, p. 333.
    Simplicithyris japonica: Zezina (1976)

    Diagnosis (Dall,1920)

    Shell resembling Platidia seminula but much larger, the valves when normally developed relatively wider, the foramen entirely confined to the attached valve, the free valve having the apex entire and a very narrow long fiattish area on each side ; the soft parts, so far as could be determined from a dry specimen softened in weak liquor potassae, do not differ in arrangement from the Mediterranean species.