22 The Paleontology of Texas I: A Session in Honor of Wann Langston, Jr.

Friday, 5 April 2013
8:00 AM - 12:00 PM
Classroom 105

COASTAL PLAIN PALEOECOLOGY, AN EXAMPLE OF CROCODYLIFORM FEEDING GROUNDS FROM THE CRETACEOUS WOODBINE FORMATION OF NORTH CENTRAL TEXAS

Paper number: 22-10
Program: Theme Sessions
Time: 11:00 AM – 11:20 AM

Authors

Abstract

This is the first report of a crocodyliform feeding ground from the Cretaceous of Texas. The fossil locality; known as the Arlington Archosaur Site (AAS), occurs in exposures of the Woodbine Formation in Tarrant County. The environmental and paleogeographic setting is an Appalachian delta plain from the southern interior seaway. The AAS preserves components of a coastal ecosystem, including dinosaurs, crocodyliforms, turtles and lungfish. Feeding traces on turtle shell fragments, and ornithopod limb bones, have been attributed to a crocodyliform based on comparisons to diagnostic types of bite marks made by modern crocodylians and the morphology of the crocodyliform itself. Marks on shells suggest an inertial feeding strategy, including crushing. Marks on dinosaur bones are consistent with traces produced during disarticulation of prey by living crocodylians. The feeding ecology implied by these traces is similar to that of modern generalist crocodylians. AAS theropod remains are rare and diagnostic tooth marks absent. Considering the number of diagnosable crocodyliform feeding traces, shed crocodyliform teeth and the comparative absence of feeding traces from other predators, the AAS crocodyliform is interpreted as the apex predator.

In association with the vertebrate fossils, 150 coprolites were recovered, demonstrating cylindrical, spiral, and scroll morphologies. The cylindrical coprolites were interpreted as crocodyliform intestinal tract material. The scroll morphologies were assigned to general reptilian and possible crocodyliform. The coprolites were not deformed, and retained their original shape. This is indicative of rapid burial in a low energy environment, soon after defecation. In modern coastal plains, crocodylians live and feed together in regions referred to as feeding grounds. The coprolites, shells, teeth, and crocodyliform remains were mapped within a single horizon, their association is interpreted as evidence of a crocodyliform feeding ground.