Henodus chelyops F. Huene, 1936

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

Henodus chelyops F. Huene, 1936

Lectotype.

GPIT-PV -30002 (‘ specimen II’ of F. Huene 1936; Fig. 12 B ).

Type locality.

Goldersbach near Tübingen-Lustnau, Baden-Württemberg.

Type horizon.

Stuttgart Formation, Middle Keuper Subgroup ( Seegis 2005). Age: Late Triassic (Carnian: Julian-Tuvalian).

Referred material.

‘ Specimens I and III-VIII’ ( GPIT-PV -30001 and GPIT-PV -30003 - GPIT-PV -30008 ) from type locality.

Diagnosis.

Distinguished by the following combination of features: skull broad transversely, flat dorsoventrally, and truncated anteriorly; anterior edges of premaxillae denticulate; maxilla with deep groove but without teeth; palatines separated from each other by broad vomers and pterygoids; palatine with single posterior crushing tooth; supratemporal fenestra small or absent; parietal broad and fan-shaped; dentary with deep groove and single posterior crushing tooth; coronoid forming small coronoid process; carapace shorter anteroposteriorly than wide transversely, distinctly embayed anteriorly and posteriorly, and linked to plastron by lateral wall; dorsomedial row of hexagonal osteoderms underlain by dorsal neural spines; and marginal row of smaller hexagonal osteoderms closely associated with underlying ribs ( Rieppel 2001 a, 2002).

Comments.

Unlike other placodonts, Henodus chelyops lived in a brackish-water lagoonal environment. Rieppel (2012) noted its unusual combination of denticulate premaxillary edges (suitable for scraping), small crushing teeth at the back of the palatines and dentaries, and a well-developed hyoid apparatus (potentially suitable for suction feeding). F. Huene (1936) also observed what he considered traces of what appeared to be baleen-like structures in the mouth. Reif and Stein (1999) interpreted Henodus chelyops as possibly herbivorous, but Pommery et al. (2021) suggested a diet of small crustaceans and snails.

References.

F. Huene (1936, 1938, 1958 a), Reiff (1942), Westphal (1975), Reif and Stein (1999), Rieppel (2001 a, 2002 a), Pommery et al. (2021).

Figures

Figure 12. Reptiles from the Lower and Middle Keuper subgroups. A. Pachypleurosaurid eosauropterygian Neusticosaurus pusillus (SMNS 53932), slab with three complete and nine partial skeletons. B. Henodontid placodont Henodus chelyops, lectotype (GPIT-PV - 30002), skeleton. Scale bar: 20 cm.