How Plesiosaurs Swam: New Insights into Their Underwater Flight Using “Ava”, a Virtual Pliosaur

Abstract

Analysis of plesiosaur swim dynamics by means of a digital 3D armature (wireframe “skeleton”) of a pliosauromorph (“Ava”) demonstrates that: 1, plesiosaurs used all four flippers for primary propulsion; 2, plesiosaurs utilized all four flippers simultaneously; 3, respective pairs of flippers of Plesiosauridae, front and rear, traveled through distinctive, separate planes of motion, and; 4, the ability to utilize all four paddles simultaneously allowed these largely predatory marine reptiles to achieve a significant increase in acceleration and speed, which, in turn, contributed to their sustained dominance during the Mesozoic.

A plesiosaurian autopodial element (Plesiosauria indet.) with remarkable articular subchondral surfaces from the Maastrichtian type area (south-east Netherlands)

“…In view of this, very detailed descriptions of elasmosaurid digits are few (although they are depicted in some papers, for example, Williston, 1906; Welles, 1943, 1952, 1962; Sato & Storrs, 2000; Everhart, 2006; Sato et al, 2006; Otero et al, 2014, Sachs & Kear, 2017) and they do not serve as a key element in generic and specific identification. However, robust plesiosaur phalanges displaying convex articular subchondral surfaces, including a rugose bone texture with foramina, have been observed in plesiosaurs of Jurassic age, for instance in the genus Cryptoclidus Seeley, 1892, and also in taxa from the Lower Cretaceous of Russia and the Upper Cretaceous of Angola (Hawthorne et al, 2019, fig. 12; Fischer et al, 2021, fig.…”

“…The presence of convex articular subchondral surfaces, including a rugose bone structure with foramina as seen in autopodials of some plesiosaurids (e.g. Araújo et al, 2015a; Hawthorne et al, 2019; Fischer et al, 2021), might be indicative of some sort of chondro-osseous bone formation in these plesiosaurs.…”

“…The presence of convex articular subchondral surfaces, including a rugose bone structure with foramina as seen in autopodials of some plesiosaurids (e.g. Araújo et al, 2015a;Hawthorne et al, 2019;Fischer et al, 2021), might be indicative of some sort of chondroosseous bone formation in these plesiosaurs. Caldwell (1997) recorded delayed ossification of distalmost limb bones in plesiosaurs, which could also have led to the remarkable morphological features observed in NHMM 2022 009.…”

Effect of aspect ratio on the propulsive performance of tandem flapping foils

“…Tandem flapping configurations e.g. insect wings (Alexander, 1984;Thomas, Taylor, Srygley, Nudds, & Bomphrey, 2004), plesiosaur flippers (Hawthorne, McMenamin, & De la Salle, 2019;Robinson & Ja, 1975) etc. are shown to outperform single flappers due to certain foil-wake interactions commonly referred to as wake recapture (Broering & Lian, 2012;Muscutt, Weymouth, & Ganapathisubramani, 2017b).…”