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Assessing dental evolution in the anaptomorphine Tetonius – Pseudotetonius (Omomyidae) lineage using quantitative and qualitative methods
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Abstract
The Willwood Formation in Wyoming's Bighorn Basin provides a virtually uninterrupted fossil record that permits formal study of gradual evolutionary change. Previous studies of the Tetonius – Psuedotetonius anaptomorphine lineage documented patterns of gradual change in lower dentition spanning 1.5 million years, resulting in progressive compaction of antemolar teeth and loss of P2 in later taxa. Here, we present results from qualitative and quantitative morphological analyses that incorporate recently recovered maxillary dentition to 1) test whether coordinated changes in the upper dentition match modifications previously documented in the lower dentition, and 2) quantify and visualize the shape changes that drive 1.5 million years of dental evolution. Our comparative morphological analyses reveal changes in the upper dentition through time; however, these transformations do not evolve in tandem with those in the lower dentition. While dentaries of Tetonius from higher meter levels show an evolutionary loss of P2, several partial maxillae of Tetonius from the same strata still possess P2. Our three-dimensional geometric morphometric analyses identify increases in crown height as the main driver of shape variation in both P4 and P4. However, the rate at which crown height increases differs between P4 and P4. Our findings suggest that the morphological changes of this lineage conform to a pattern of mosaic evolution. The presence of P2 in higher meter levels and increased P4 crown height relative to P4 may indicate retention of a vestigial structure while selective pressures acted on increasing the crown height of P4 to perform or enhance specific masticatory functions.
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These are the slides from a presentation given at American Association of Biological Anthropologists on 03/14/2025.
Date
2025-03-14
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University of Kansas
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Keywords
Primates, Paleontology, Evolution, Geometric morphometrics