New Mexico Geological Society Annual Spring Meeting — Abstracts

An isolated proximal caudal centrum and an isolated right femur pertaining to tyrannosaurid dinosaurs from the Upper Cretaceous deposits of the San Juan Basin, New Mexico, preserve several elongate lesions, which are interpreted as bite marks or feeding traces made by another tyrannosaurid. The femur was recovered from the Upper Campanian deposits of the De-na-zin Member of the Kirtland Formation, whereas the isolated caudal centrum was recovered from the Maastrichtian deposits in the Naashoibito Member of the Ojo Alamo Formation. The lack of associated cranial material with the bones precludes their generic identification. The absence of bone surface healing around the lesions indicates the biting most likely took place post-mortem. Intensely tooth-marked bones clearly show that the San Juan Basin tyrannosaurids fed upon the remains of not only ceratopsians, hadrosaurs, and sauropods, but also conspecifics. The bite marks described here represent three categories: "bite-and-drag", "puncture", and "bite-and-crush." The "bite-and-drag" marks are located in the anteroventral and in the anteroventral regions of the centrum. Some of these bite marks are short-and-shallow, whereas others are long-and-deep. Most of the "puncture" marks are located in the anterodorsal region of the centrum, whereas some others are located within the "bite-and-drag" marks. The "bite-and-crush" mark is represented by a single, large, ovoid-shaped lesion containing a small "puncture" mark. The bite marks on the right femur are located on the anterior, posterior, and dorsal surfaces of the femoral neck and head, including the lesser trochanter, at the midshaft, and largely on the distal condyles and crista tibiofibularis. The specimens provide new evidence for cannibalism among tyrannosaurids and add to previous knowledge of the feeding behaviour of these iconic predators based on inferred bite marks.