Polymorphodon adorfi Sues, Schoch, Sobral & Irmis, 2020

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

Polymorphodon adorfi Sues, Schoch, Sobral & Irmis, 2020

Holotype.

SMNS 91343 , disarticulated partial skeleton preserved on three blocks of mudstone. Identifiable elements include a partial left premaxilla (buried in matrix), both maxillae, left frontal, right postorbital, left jugal (buried in matrix), both quadrates, occipital portion of braincase, incomplete parabasisphenoid, partial right and nearly complete left pterygoid, fragments of possible vomers, partial dentaries, caudal vertebrae, complete left and fragment of right ilium, left? ischium, pubis, left femur, left tibia, possibly left fibula, two metatarsals, and other autopodial elements.

Type locality.

Schumann Quarry, Eschenau, Vellberg municipality, Schwäbisch Hall district, Baden-Württemberg.

Type horizon.

Untere Graue Mergel, Bed E 6, Erfurt Formation, Lower Keuper Subgroup. Age: Middle Triassic (Ladinian: Longobardian).

Referred material.

SMNS 91400 , two blocks of mudstone preserving disarticulated skeletal remains including a left premaxilla, incomplete left maxilla, partial right jugal, partial right dentary, partial braincase, left pterygoid, and teeth.

Diagnosis.

Distinguished by the following combination of features: premaxilla with long, leaf-shaped posterodorsal process that is slightly longer than body of element and with deep lateral fossa anteroventral to external narial fenestra; five conical, gently recurved premaxillary teeth; mesial and distal carinae of labiolingually flattened maxillary and dentary tooth crowns with large, somewhat hook-shaped denticles aligned at distinct angle to apicobasal axis of tooth crown; and presence of ledge on medial surface of maxilla above interdental plates.

Comments.

The phylogenetic analysis by Sues et al. (2020) found Polymorphodon adorfi among Eucrocopoda in a polytomy with Proterochampsia, Archosauria, and various other taxa. Subsequently, Ezcurra and Sues (2021) recovered it in a basal position among Proterochampsia. Unlike other known proterochampsians, Polymorphodon adorfi apparently lacked osteoderms.

References.

Sues et al. (2020), Ezcurra and Sues (2021).