Campanian-Maastrictian Ankylosaurs of West Texas

Abstract

Big Bend National Park is known for its unique Late Cretaceous fauna, such as Alamosaurus sanjuanensis and Quetzalcoatlus northropi. Most major groups of dinosaurs are represented in the Late Cretaceous strata, which ranges from the Early Campanian through the Late Maastrichtian (approximately 17.6 Ma). However, one group of herbivorous dinosaurs, the armored ankylosaurs, have never been described in detail from this area. Fossil remains of these dinosaurs are sparse and fragmentary; the only skeletal elements found in abundance are the dermal plates, known as osteoderms, that these animals utilized for defense and display. Previous studies such as Scheyer and Sander (2004), Hayashi et al. (2010), and Burns and Currie (2014) have attempted to classify ankylosaurs by families, genera, and even species by using thin sections to examine the paleohistology of osteoderms. Using new microCT scanning techniques this study has attempted to classify the ankylosaur specimens found in Big Bend so that the fossil record for this area during the Campanian and Maastrichtian.