Taphonomy of a Lance Formation(Maastrichtian, WY) Dinosaur Bonebed with a Focus on Tooth Traces
The Rose Quarry bonebed found in the Maastrichtian Lance Formation of eastern Wyoming possesses a complex blendof taphonomic signatures. Disarticulated, disassociated, fragmented bones of various states of abrasion from dinosaurs, turtles, and crocodilians are clustered together in a channelized sandstone unit. The mismatched taphonomic signatures of the bonebed suggest that it is amixed assemblage, containing bones with different taphonomic histories that were washed together by a flood event. Sedimentological data,includingthe presence of large mud clasts in the bonebed,agree well with this hypothesis. The abundant breakage of the bones in the Rose Quarry bonebed is attributed mainly to trampling. This study highlights the striking variability possible in fluvial bonebeds, including differences in pre-burial history, depositional mechanism, subenvironment, and post-burial history. Although only a few Rose Quarry bones show evidence of tooth traces, a similar nearby bonebed contained a tyrannosaurid metatarsal (HRS13997)that possessed numerous scores on the posterolateral surface near its ventral end. The presence of a Knethichnus parallelum tooth trace, the first known on a tyrannosaurid bone, allows for us to measure the widths of the striations left by the tooth denticles scraping along the bone’s surface. Comparison with theropod teeth from the Lance Formation leads us to concludeit was bitten by another tyrannosaurid, suggesting possible cannibalism in the species Tyrannosaurus rex.
Earth Sciences, Paleontology, Paleontology -- Wyoming; Taphonomy; Fossilization; Paleoecology; Sedimentary geology, Lance Formation (Maastrichtian); Rose Quarry Bonebed; Fluvial bonebeds; Tooth traces; Post-burial history; Dinosaurs
Networked Digital Library of Theses and Dissertations