26 Old Collections, New Tricks

This session highlights how re-examination and contemporary analysis of geoscience collections (i.e., rock, fossil, and archival collections, or geologic maps) can advance science, rewrite historical narratives, and contribute to discussions on social justice.

Monday, 23 March 2026
1:30 PM - 5:30 PM
CCC, Room 25

Morphological Control of Swimming Function in Semi-Aquatic Tetrapods

Paper number: 26-2
Program: Technical Sessions
Time: 1:55 PM – 2:15 PM

Authors

Abstract

     Secondarily aquatic tetrapods employ several swimming styles that exist within a spectrum of locomotory function, but that broadly fall under axial or appendicular swimming. Both modes are able to use oscillation, the use of flapping motion as a means of propulsion, or undulation, where a wave is passed down the body. These swimming styles span different morphologies. We sought to understand why certain swimming styles are adopted to begin with in these secondarily aquatic transformations. We hypothesize that the trunk-to-tail ratio of semi-aquatic tetrapods is correlated with swimming function, following a morphological pattern where body proportions control the style of propulsion in water. To test this, we compiled a dataset of every known extinct and extant semi-aquatic tetrapod with functional limbs, excluding groups with rigid shells (turtles) that may limit swimming capabilities. We then measured the length of the trunk and tail of each. Extinct species measurements were retrieved through previously documented and reconstructed specimens, applying new research to established findings. We then performed correlation tests in R, which revealed a positive relationship between trunk-to-tail ratio and swimming style (axial or appendicular). Longer trunks and shorter tails are correlated with appendicular swimming, while shorter trunks and longer tails are correlated with axial swimming. These results suggest that morphological starting point and initial body proportions dictate some functional aspects of the trajectories of these secondarily aquatic transformations.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411405

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