Master's Theses or Doctor of Nursing Practice

Department

Geosciences

Degree Name

Master of Science (MS)

Abstract

Teleoceras is a genus of rhinocerotids that belongs to the Tribe Teleoceratines and was widespread across North America from the late Early Miocene into the Early Pliocene. This genus was very successful, spreading across the continental United States from Florida and Tennessee to California and Washington state down to central Mexico and Honduras. Teleoceras is characterized by having a large, rounded chest cavity and short limbs with relatively high crowned teeth and lower incisors modified into tusk-like teeth. Initial ecological comparisons were made to the modern hippopotamus based on proportions of the chest cavity and its hypsodont dentition. Stable carbon isotopic analyses of Teleoceras proterum material from the Early Pliocene of Florida strongly suggest that T. proterum was a terrestrial mixed feeder that heavily consumed C4 grasses. However, for material dated before 4.5 mya, nothing could confidently be said about the dietary preferences of Teleoceras other than the fact that it was consuming C3 foliage. Evidence from gut content and tooth crown height from sites dated before the spread of C3 grasses around 7 Mya (e.g., Ashfall Fossil Beds) suggest that Teleoceras was a mixed feeder. Studies continue to suggest that some species of Teleoceras were browsers/mixed feeders while others suggest that species like Teleoceras hicksi range from browsing to grazing. In this study, we used a new 2D Geometric Morphometric Mesowear Analysis on eight Teleoceras fossiger individuals from the Late Miocene Minium and Jack Swayze Quarries of Kansas and four Teleoceras aepysoma individuals from the Early Pliocene Gray Fossil Site in Tennessee in order to understand their feeding ecology. We created a new dataset of 137 individual perissodactyls with 82 equid individuals and 55 rhinocerotid individuals with dietary information collected from the literature to classify T. fossiger and T. aepysoma. Our results show a mixed feeding ecology for T. fossiger and a browsing feeding ecology for T. aepysoma. When comparing between the PCA and DFA results of the ectoloph and metacone data, the ectoloph data did a better job of separating taxa from each other, suggesting it to be a better marker of feeding ecology. Both PCA and DFA results, corresponding to the dietary classifications of T. fossiger and T. aepysoma, align with previous microwear, mesowear and stable isotope studies.

In the following study, we used a Traditional Microwear Analysis on seven individuals of Teleoceras fossiger /Teleoceras cf. fossiger (five upper molars) from the Minium Quarry and Jack Swayze in Kansas as well as 8 individuals of Teleoceras aepysoma (15 upper molars) from Gray Fossil Site in Tennessee in order to observe the feeding ecology of these two taxa from their last meals. The dataset of T. fossiger and T. aepysoma microwear results were combined with microwear data from extant rhinocerotids in order to classify. Our results weakly suggest that T. fossiger and T. aepysoma were eating browse near the time of their death. Both dietary classifications do fall within previous interpretations of the feeding ecology of these taxa. When combining both mesowear and microwear results, they point to T. fossiger as a C3 mixed feeder (consumption of both graze and browse) with a good component of browse while T. aepysoma comes out as a C3 browser. Since mesowear looks at tooth wear that is created over the span of an individual’s lifespan and microwear analyzes the tooth wear accumulated from an organism’s last meals, the combination of which can give a lot of nuances as to differences between overall diet and diet variation due to seasonality. When looking at T. fossiger, our results suggests responded to the climatic changes by consuming both C3 browse and graze, which likely helped them survive initially as the Great Plains region transitioned, but then hurt them as C4 grasslands spread. Meanwhile, when looking at T. aepysoma, it suggests that their response to the continuing climatic changes by confining themselves within the stable closed canopy environment of Gray Fossil site and consuming C3 browse.

Keywords

Miocene, Mesowear, Microwear, Teleoceras fossiger, Teleoceras aepysoma

Advisor

Dr. Reese Barrick

Date of Award

Fall 2025

Document Type

Thesis

Rights

© The Author

Comments

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