Dyoplax arenaceus O. Fraas, 1867

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

Dyoplax arenaceus O. Fraas, 1867

Holotype.

SMNS 4760 , nearly complete skeleton missing most of the limbs and the distal end of the tail, preserved as a natural cast (Fig. 15 A ).

Type locality.

Leins Quarry at Sonnenberg, Stuttgart, Baden-Württemberg ( Maisch et al. 2013).

Type horizon.

Upper portion of Stuttgart Formation, Middle Keuper Subgroup. Age: Late Triassic (Carnian: Tuvalian).

Diagnosis.

Distinguished by the following combination of features: Premaxillae with long posterodorsal processes separating nasals for considerable distance; antorbital fenestra low, long, and oval; antorbital fossa deep, distinctly rimmed; nasal and jugal not entering margin of antorbital fenestra; jugal deep, with distinct ridge separating ventrolateral and dorsolateral surfaces; dorsal dermal armor comprising pair of rows of paramedian osteoderms; and presence of cervical lateral osteoderms ( Maisch et al. 2013).

Comments.

In the original description O. Fraas (1867) did not assign Dyoplax arenaceus to any specific group of reptiles. Due to its preservation as a natural cast, it is difficult to identify many anatomical features. F. Huene (1902) first considered Dyoplax arenaceus a pseudosuchian. Walker (1970) assigned it to Erpetosuchidae . Lucas et al. (1998) interpreted it as an early crocodylomorph. Maisch et al. (2013) and Foffa et al. (2021) explicitly supported referral to Erpetosuchidae .

References.

O. Fraas (1867), Walker (1970), Lucas et al. (1998), Maisch et al. (2013); Foffa et al. (2021).

Figures

Figure 15. Reptiles from the Middle Keuper Subgroup. A. Erpetosuchid pseudosuchian Dyoplax arenaceus, holotype (SMNS 4760), skull and cervical region in lateral view. Scale bar: 2 cm. B. Parasuchid Parasuchus angustifrons, holotype (SNSB-BSPG 1931 X 502), incomplete cranium in dorsal view. Scale bar: 5 cm. C. Parasuchid Ebrachosuchus neukami, holotype (SNSB-BSPG 1931 X 501), cranium in dorsal view. Scale bar: 10 cm. B, C from Lautenschlager and Butler (2016) – CC-BY 4.0.