Abstract

Tyrannosaurid tooth measurements have been shown to be a powerful tool for systematic analyses, as well as for studies on function and evolution of theropod dentition. In this analysis, a variable not previously addressed in depth is added to the tyrannosaurid data set. The angle between the anterior and posterior carinae can be difficult to measure consistently and a method is hereby proposed through the use of a digitizer. Five tyrannosaurid genera were analyzed: Tyrannosaurus, Tarbosaurus, Albertosaurus, Daspletosaurus, and Gorgosaurus. Only in situ data were used, and therefore some of the taxa had a limited amount of information available for this analysis. The measurements were analyzed through multivariate analyses using Paleontological Statistics (PAST), version 2.06. The analyses included principal component analyses (PCAs), discriminant analyses (DAs), and canonical variates analyses (CVAs). The results of these analyses revealed that the angle between carinae contributes significantly to the variation in the tyrannosaurid tooth data set. Additionally, this variable showed a strong correlation to tooth function (and, consequently, to tooth families), rather than tooth size. The variation observed between taxa at this stage seems insufficient for systematic purposes, however additional in situ data would help improve the effectiveness of this tool.

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