Proterochersis robusta E. Fraas, 1913 a

Sues, Hans-Dieter & Schoch, Rainer R., 2025, Synopsis of the Triassic reptiles from Germany, Fossil Record 28 (2), pp. 411-483 : 411-483

Proterochersis robusta E. Fraas, 1913 a

Holotype.

SMNS 12777 , poorly preserved steinkern of shell with plastron and right portion of pelvis.

Type locality.

Rudersberg, Baden-Württemberg.

Type horizon.

Lower Stubensandstein (S 1), Löwenstein Formation (equivalent of Arnstadt Formation), Middle Keuper Subgroup. Age: Late Triassic (Norian: Lacian).

Referred material.

Szczygielski and Sulej (2016) listed 20 specimens from German localities, all but one of which are housed at SMNS.

Diagnosis.

Distinguished from Proterochersis limendorsa by the following features: absence of serrated marginals; presence of supernumerary anterior marginals; broad contact of cervical with adjacent marginals; transversely extending lateral sulcus of vertebral I; evenly thin carapacial bones; and immobile cervical VIII ( Szczygielski and Sulej 2016; Fig. 14 A ).

Comments.

E. Fraas (1913 a) named a second species, Proterochersis intermedia , based on a fragmentary, flattened steinkern of a partial shell ( SMNS 11396 ) from Stuttgart-Rohracker, but Szczygielski and Sulej (2016) referred this specimen to Proterochersis robusta . Karl and Tichy (2000) proposed a new taxon, Murrhardtia staeschei , for an unnumbered CSMM specimen, which preserves most of a plastron and much of a carapace. Szczygielski and Sulej (2016) also synonymized this species with Proterochersis robusta .

Szczygielski (2021) noted that Chelytherium obscurum Meyer, 1863 is probably synonymous with Proterochersis robusta , as first suggested by Baur (1887). This taxon is based on a series of well-preserved shell fragments ( NHMUK PV OR 38650 –38653) from the lower part of the Löwenstein Formation in the vicinity of Stuttgart. However, in the interest of nomenclatural stability, we retain Proterochersis robusta because this binomen has long been well-established in the literature whereas this is not the case with Chelytherium obscurum .

References.

E. Fraas (1913 a), Szczygielski and Sulej (2016), Joyce (2017), Szczygielski (2021).

Figures

Figure 14. Reptiles from the Middle Keuper Subgroup. A. Stem-turtle Proterochersis robusta (SMNS 17561), shell. Length 30 cm. B. Stem-turtle Proganochelys quenstedtii (SMNS), reconstructed skeleton including shell. C. Lepidosauromorph Elachistosuchus huenei, holotype (MB. R. 4520), incomplete skull in lateral and dorsal view. Scale bar: 1 cm. D. Sphenodontian rhynchocephalian Parvosaurus harudensis, holotype (MB. R. 4520.2), CT-based rendering of incomplete skull in dorsal view. Scale bar: 5 mm. From Freisem et al. (2024) – CC-BY 4.0.