Saturday, September 2, 2017

[Paleontology • 2017] Deltasuchus motherali • A Large Neosuchian Crocodyliform from the Upper Cretaceous (Cenomanian) Woodbine Formation of North Texas


Deltasuchus motherali
Adams, Noto & Drumheller, 2017

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.



FIGURE 3. A, articulation of cranial elements of Deltasuchus motherali, gen. et sp. nov., in dorsal view. B, reconstruction of the complete skull of D. motherali. Missing elements in gray, based on Paluxysuchus newmani (Adams, 2013).   Scale bar equals 10 cm.

SYSTEMATIC PALEONTOLOGY

CROCODYLIFORMES Hay, 1930
MESOEUCROCODYLIA Whetstone and Whybrow, 1983
NEOSUCHIA Benton and Clark, 1988

DELTASUCHUS, gen. nov.

Type Species—Deltasuchus motherali, sp. nov.

Etymology—Deltasuchus, ‘Delta’ in reference to the coastal delta plain deposits of the Woodbine Formation in which the new taxon was found; and ‘suchus,’ derived from ‘Souchos,’ the Greek term for the Egyptian crocodile god, Sobek.

DELTASUCHUS MOTHERALI, sp. nov.

Etymology— Deltasuchus motherali, in honor of Austin Motheral, who discovered the type specimen.

Dr. Stephanie Drumheller, Dr. Thomas Adams, and Dr. Chris Noto with the skull of Deltasuchus motherali.

AAS volunteers working to uncover fossils, including those of Deltasuchus, in 2009.


Thomas L. Adams, Christopher R. Noto and Stephanie Drumheller. 2017. A Large Neosuchian Crocodyliform from the Upper Cretaceous (Cenomanian) Woodbine Formation of North Texas. Journal of Vertebrate Paleontology. DOI:   10.1080/02724634.2017.1349776 

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