A large neosuchian crocodyliform from the Upper Cretaceous (Cenomanian) Woodbine Formation of North Texas

ABSTRACT

A new taxon of neosuchian crocodyliform, Deltasuchus motherali, gen. et sp. nov., is described on the basis of a partial skull recovered from the Arlington Archosaur Site within the Upper Cretaceous (Cenomanian) Woodbine Formation of north-central Texas. This productive locality represents a delta plain ecosystem preserving a diverse coastal fauna, including lungfish, turtles, dinosaurs (ornithopods and theropods), and crocodyliforms. Prior to this discovery, the only identified crocodyliforms from the Woodbine Formation had been the longirostrine taxa Terminonaris and Woodbinesuchus. This new taxon is differentiated from other known crocodyliforms by the presence of dual pseudocanines on both the dentary and maxilla; anterior and posterior rami of jugal comparable in depth; anterolaterally facing margin on the dorsal portion of the postorbital; contact between the descending process of the postorbital and the ectopterygoid; and a large, deep fossa on the ventral surface of the quadrate. Phylogenetic analysis recovers D. motherali as the sister taxon to Paluxysuchus newmani from the Lower Cretaceous Twin Mountains Formation of Texas. This clade lies within Neosuchia basal to Goniopholididae + Eusuchia. The associated cranial elements of this new crocodyliform represent a large, broad-snouted individual, an ecomorphotype often associated with the semiaquatic ambush predator niche in this clade, and one not previously reported from the formation.

ACKNOWLEDGMENTS

We thank the Huffines family and R. Kimball of Johnson Development, who generously provided access to the AAS. Thanks to A. Sahlstein, P. Kirchoff, and B. Walker, who discovered the site. We are grateful to J. Beeck, T. Diamond, R. Fry, S. King, A. Camp, R. Colvin, A. Sahlstein, B. Carter, P. Scoggins, M. Cohen, D. Summerfelt, A. Miramontes, and the army of dedicated volunteers who helped in excavation and preparation of the material over the years. Thanks to A. Motheral who discovered the first elements of the holotype. We gratefully acknowledge advice and input from L. Jacobs, A. Fiorillo, R. Tykoski, M. Polcyn, C. Holliday, and C. Brochu. We thank A. C. Pritchard, S. W. Salisbury, and A. Turner for their valuable comments that helped improve the manuscript. Access to research collections was possible thanks to K. Morten (DMNH), D. Winkler (SMU), and M. Brown (TMM). Taxon silhouettes come from Phylopic (phylopic.org) and were created by P. Buchholz (hadrosauroid), S. Hartman (turtle), Smokeybjb (crocodyliform), and N. Tamura (lissamphibian). These images are used under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 license. This study was supported by funding from the National Geographic Society Conservation Trust Grant C325-16, as well as the many contributors to our Experiment.com campaign. We dedicate this paper to the memory of D. Main. None of this would have been possible without him.