187-5 Swimming With or Without a Paddle: A CFD Analysis of Mosasaur Body Plan Hydrodynamics

Session: Phylogenetic and Computational Approaches in Paleobiology and Paleoecology (Posters)

Presenting Author:

Authors:

Abstract:

Over the final 30 million years of the Cretaceous, mosasaurs replaced ichthyosaurs and plesiosaurs as the top predators in marine ecosystems, filling a number of predatory niches in the oceans over a relatively short period of time. However, despite their importance to Cretaceous marine ecosystems, there are relatively few studies of their swimming biomechanics – one of the fundamental parts of the paleobiology. The long bodies and tails of these animals have led to a focus on their capability as undulatory swimmers. Prior research has used fossil measurements and kinematic proxies to estimate hydrodynamic properties such as optimal cruising speed and drag for these animals. In this work we leverage Computational Fluid Dynamics to develop more detailed insight into hydrodynamic consequences of mosasaurid body plans, focusing primarily on drag and wake structures. We produce and compare a set of 3D modeled archetypal mosasaur soft body reconstructions, each in 4 different poses that bound the possible variety of poses these animals could take. We examine how drag force is distributed across the body and the structure of the fluid field behind the body. We find that only a limited agreement of our results with the estimates of prior research, which hinge on the presence and configurations of the paddles. In all previous studies, the paddles are ignored or abstracted away for at least part of the estimate leading. Our findings show that the paddles are capable of imposing a greatly outsized effect on the animal’s drag, in some cases multiple times that of the body alone. These results indicate a more nuanced and flexible hydrodynamic experience for these animals which they could potentially leverage to their advantage ultimately facilitating their rise as apex predators. Finally, we speculate on how these effects would also make these paddles quite capable force producing units depending on their range and style of motion.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10814

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.