Distinct feeding biomechanics in Late Cretaceous marine reptiles from the Western Interior Seaway

Abstract Sympatry of numerous predatory marine reptiles appears to be the rule rather than the exception in many Mesozoic formations, implying that these lineages are likely to have evolved some form of ecological partitioning. Many studies have focused on dental morphology as a proxy for the feeding habits of aquatic tetrapods, but much more ecological insight may be gained through simulations of the mechanical performance of craniomandibular elements. Here, we conducted the first, large‐scale comparative study of marine reptile jaw biomechanics, applying muscle‐driven finite element analyses (FEA) on a dataset of high‐resolution three‐dimensional models. Our study‐system included mosasaurids and polycotylid plesiosaurians from the Santonian–Maastrichtian of the Western Interior Seaway (WIS), a vast inland sea that stretched longitudinally across North America during the Late Cretaceous. Muscle insertions were identified to reconstruct jaw adductor muscles and simulate respective muscle and bite forces. We simulated realistic muscle traction dynamics during biting, including simulations at multiple opening angles and bite locations. We recover clearly distinct biomechanical performances among the sample, notably between the slender‐snouted mosasaurids (e.g. Clidastes ) plus polycotylids, and the robust‐jawed mosasaurids (e.g. Prognathodon ). By integrating jaw length and other biomechanical metrics derived from our analyses, we provide strong support for differential biting mechanics among these marine predators, which doubtless influenced their ecological roles. Our results offer deeper insight into the feeding ecologies of Late Cretaceous marine reptiles, and provide a unified protocol to assess the role of feeding biomechanics in niche partitioning among sympatric marine reptiles from well‐sampled regions.