Sink your teeth into this: Assessing carnivorous dinosaur diversity using isolated tooth fossils

Isolated teeth from carnivorous dinosaurs are relatively abundant in the terrestrial fossil record, providing important indicators of theropod diets and diversity. Currently, fossils excavated throughout the Morrison Formation (157-150 million years ago) display high predator diversity, implying ecosystems far more productive than what are seen today. The separation of these carnivores into more distinct temporal and geographic ranges, however, would more similarly reflect modern ecosystems. Using statistical methods established in previous papers, this study aims to identify a set of theropod teeth from Morrison-aged sites in Wyoming in order to evaluate theropod diversity during this time. Following the methodology of a well-cited publication, we conducted a discriminant function analysis (LDA) through PAST v4.17 using the most modern version of a quantitative dataset. The analysis of a dataset including most theropod groups yielded stratigraphically improbable results (clade-level: Non-megalosaurian Megalosauroidea, Neovenatoridae, Therizinosauria, Metriacanthosauridae, Noasauridae, Carcharodontosauridae; taxon-level: Carnotaurus, an unnamed dromaeosaurid, Marshosaurus, Raptorex, Dubreuillosaurus, Berberosaurus, Neovenator, Falcarius, Australovenator, Abelisauridae, Deinonychus, Giganotosaurus). To improve these results, an additional Morrison-specific analysis was run, assigning 16 unknown teeth across 3 clades and 3 taxa. While the specimens were able to be statistically categorized (clade level: Non-abelisauroid Ceratosauria, Non-megalosaurian Megalosauroidea, Allosauridae; taxon-level: Ceratosaurus, Marshosaurus, Allosaurus), unrepresented Morrison taxa and the damaged state of the specimens may have limited the accurate classification of these results. Further research, especially emphasizing qualitative analysis, could improve future results.