INFERRING DIET IN THE MOSASAUR CLIDASTES USING SKULL AND PTERYGOID TOOTH MORPHOLOGY OF TOXICOFERAN SQUAMATES

Without the direct evidence of stomach content, the diet of fossil organisms can be difficult to determine. In this study, we sought to reconstruct the diet of the mosasaur genus Clidastes utilizing a morphospace of skull morphology featuring squamates within the proposed clade Toxicofera. We collected 11 linear measurements of skull bones considered important for manipulating food in extant squamates, including anguimorphs, snakes, and iguanids. We measured 202 specimens representing 90 species from collections in the National Museum of Natural History, the Sternberg Museum of Natural History, the Peabody Museum of Natural History, and the Alabama Museum of Natural History. We then used multivariate statistical analyses to develop a morphospace which allowed us to categorize the toxicoferan squamates on the basis of their diet and thus infer diet in Clidastes. In addition, we utilized a phylogeny-based least squares regression to test for trends in the number of pterygoid teeth throughout the evolutionary history of mosasaurs as currently hypothesized.

Preliminary analyses show that traits relating to the number of pterygoid teeth and the proportion of the pterygoid covered by teeth, in addition to body size, explain most of the morphological variation in toxicoferan squamates. The number of pterygoid teeth Clidastes possesses is not significantly greater than that of other mosasaurs, but in Clidastes, a much greater percentage of the pterygoid surface is covered by teeth. This is consistent with observations made of other piscivorous squamates, specifically snakes, and suggests a similar diet for Clidastes.