Eryopidae Cope, 1882

Werneburg, Ralf & Witzmann, Florian, 2024, The last eryopids: Clamorosaurus and Syndyodosuchus from the late Kungurian (Cisuralian, Permian) of Russia revisited, Fossil Record 27 (3), pp. 353-380 : 353-380

Eryopidae Cope, 1882

Diagnosis.

Synapomorphies (from Werneburg et al. 2023, after Sawin 1941; Romer 1947; Boy 1990; Milner 1989, 1990; Werneburg and Steyer 1999; Schoch and Hampe 2004; Werneburg 2007; Werneburg and Berman 2012; Schoch and Milner 2014): (1) Enlarged choana medially wide; (2) Ectopterygoid, palatine and vomer only with two or three fangs (without subsequent smaller teeth); (3) Lacrimal reaches anteriorly to the naris or septomaxilla; (4) Enlarged posterior width of skull (pS w / S l = 0.92–1.10; compare Fig. 2 ); (5) Posterior part of the cultriform process widened (partly); (6) Interclavicle of adults proportionally small and broadly-ovate in outline; (7) Ilium with vertically directed dorsal process, which is anteroposteriorly widened dorsally.

All three species to be revised, Clamorosaurus nocturnus , C. borealis and Syndyodosuchus tetricus , fulfill the first four criteria of the family diagnosis. The fifth diagnostic feature is not present in all eryopid genera, only in Eryops and Onchiodon . The sixth and seventh diagnostic features concern the interclavicle and ilium, which have not been recorded in all three species. In this respect, all these species can be assigned to the family Eryopidae .

Figures

Figure 2. Reconstructed eryopid skull roof with measured distances. Abbreviations: aS w, anterior width of skull at level of maxilla-premaxilla sutures; H l, postorbital midline length of skull from level of posterior margins of orbits; H w, postorbital width of skull between lateral margins of supratemporals; IN w, minimum internarial width; IO w, minimum interorbital width; J w, transverse width of jugal at maximum lateral lacrimal extent of orbit; La l, maximum length of lacrimal; La w, maximum transverse width of lacrimal; mS w, midlength width of skull at midlength level of orbits; O l, maximum length of orbit; p, number of dermal skull pits or valleys per inch 2 (6.452 cm 2) mainly from frontal and jugal at midlength level of orbits; PO l, preorbital midline length of skull from level of anterior margins of orbits; Po l, maximum posterior length of postorbital from posteriormost extent of orbit; Po w, maximum transverse width of postorbital at contribution to orbital margin; pS w, maximum posterior width of skull at level of posterolateral margins of cheeks; S l, midline skull length; Th l, length of tabular horn region between levels of posterior tabular corner and occipital midline margin; W w, maximum transverse width of cheek from lateral margin of supratemporal anterior to otic notch.