A new archosauriform reptile with distinctive teeth from the Middle Triassic (Ladinian) of Germany

ABSTRACT

Skeletal remains of a small reptile with a distinctive dentition from the Lower Keuper (Erfurt Formation; Middle Triassic, Ladinian) of the Schumann quarry near Eschenau, in the municipality of Vellberg in Baden-Württemberg, Germany, represent a new taxon of non-archosaurian archosauriforms, Polymorphodon adorfi. It is diagnosed by various craniodental autapomorphies, including 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; premaxilla with long, leaf-shaped posterodorsal process that is slightly longer than body of element; presence of prominent lateral fossa on premaxilla anteroventral to external narial fenestra; premaxilla with five gently recurved, conical teeth; medial surface of maxilla with distinct ledge above the interdental plates; and maxilla and dentary with distinctly heterodont dentition. Phylogenetic analysis recovered Polymorphodon adorfi in a position crownward of Erythrosuchus africanus but in an unresolved polytomy with derived non-archosaurian archosauriforms such as Proterochampsidae and Euparkeria capensis and with Archosauria. The maxillary and dentary teeth of Polymorphodon adorfi differ from those of other non-archosaurian archosauriforms and indicate a different, possibly omnivorous diet, suggesting that these reptiles were more diverse in terms of feeding habits than previously assumed.

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ACKNOWLEDGMENTS

We are greatly indebted to the avocational collectors who donated important specimens from the Schumann quarry to the SMNS and provided much technical help during the museum’s field campaigns: W. Kugler, F. Ullmann, B. Rozynek, P. Haubold, U. Günter, A. Bartholomä, and C. Straub. We thank the Schumann family for granting access to the site and for their continued generous support. N. Adorf, I. Rosin, M. Kamenz, and M. Battenstein (all SMNS) participated in the excavations at the Schumann quarry. I. Rosin (SMNS) prepared the specimens with her customary skill. J. Rieger (Zeiss Metrology Services) undertook the micro-CT scanning of SMNS 91343. Free access to the TNT software is provided courtesy of the Willi Hennig Society. H.-D.S. gratefully acknowledges receipt of an Alexander von Humboldt Award for Excellence in Research and Teaching. We thank J. B. Desojo, H. Hagdorn, S. L. Nesbitt, and D. Seegis for discussions. G. Bever, C. Foth, and an anonymous reviewer offered helpful comments on a draft of the manuscript.