A CRETACEOUS TURTLE SHELL FORM GLENROCK WYOMING

GPM 342 is a baenid turtle shell recovered from the Glenrock Exposure of the Lance Formation. The medial portion of the carapace is not preserved, having been lost to erosion, however, the plastron is complete. GPM 342 suffers from dorsoventral compactions, but is circular, with a circumference of 64.5 cm, a plastron mediolateral width of 30 cm, and a plastron anteroposterior length of 26 cm. GPM 342 is identified as Plesiobaena antiquia based on the smooth texture of the shell, the lack of scalloping on the posterior carapace margin, and the proportions of the anterior and posterior plastron lobes. Near the right anterior plastron margin are two small, circular puncture holes. Consistent with the form of bite marks abundantly documented on extant and fossil turtle shells, these punctures were likely left by a crocodylomorph. No evidence of bone remodeling and healing is associated with the punctures, and the wound is, therefore, interpreted as having occurred near or after death. Found in close association are fragmentary remains of a Basilemys turtle and two Trionychidae turtles.