Meeting Abstract
Extant crocodilians and odontocetes exhibit a similar range of cranial morphology, including, rostra that are similarly elongate to robust. Why have these two groups, which have been phylogenetically separate for 250 million years, diversified in such a similar way within the aquatic environment? Here we present the results from a quantitative analysis of morphology, performance, and feeding ecology within extant crocodilians and odontocetes. Our analysis sheds light on the constructional morphology of these taxa and offers an explanation for this ecomorphological convergence. Furthermore this study provides a robust foundation for predicting ecological traits in extinct marine reptiles such as ichthyosaurs, mosasaurs and sauropterygians. Raw data were collected in the form of CT and 3D laser scans from a wide range of extant taxa for use in morphometric and biomechanical analyses. We used 1) 3D geometric morphometrics to assess variation in morphology, 2) finite element analysis to quantify the ability of the skulls to resist loading, and 3) computational fluid dynamics to quantify the drag induced by the head of three species of crocodilians during sweep feeding. We also compiled dietary data from relevant literature to produce quantitative numerical data on prey type and size. Our results show that cranial morphology is highly associated with biomechanical capabilities and feeding niche. Elongate and dorso-ventrally compressed taxa have evolved for hydrodynamic efficiency and feed on lower minimum prey sizes. In contrast robust morphotypes have evolved to increase skull strength in some taxa as well as to increase suction ability in others.
