In this study, I conducted research on the cause and effect relationship between Hyaenodon’s body size and the fluctuating climate throughout the Eocene and Oligocene. Hyaenodon is an extinct genus of mammals that belonged to a group of carnivorous creodonts called Hyaenodontidae. My focus will be the study of Hyaenodon’s teeth, a proxy for body size in mammals. Hyaenodon was a fierce predator due to its extremely powerful jaws. Furthermore, Hyaenodon’s teeth were specially adapted for slicing through meat, making food digestion more efficient. All of the Hyaenodon fossil collections material I measured was stored in the Field Museum of Natural History in Chicago.
I will be testing the theory of Bergmann’s Rule on Hyaenodon dental data. Bergmann’s Rule states that during periods of changing temperatures, the result of that change will be an alteration in the size of an animal, reflecting the warmer or cooler temperatures. What his theory illustrates is that during warmer periods, we expect to see smaller-bodied animals because they have an easier time releasing heat in hot temperatures. For cooler temperatures, we expect to find larger-bodied animals because it is easier for them to store heat to adapt for colder temperatures. Approaching the Eocene and Oligocene boundary, we saw a sharp rise in temperature called the Eocene Thermal Maximum, about 50 million years ago. Across the boundary, there was a fast drop in temperature. This provides a perfect change in climate for Bergmann’s Rule to be tested. I expect to find that Hyaenodon increased in body size over the Eocene and Oligocene boundary, due to the decreasing temperature.
I tested the relationship of body size in Hyaenodon and changing climates across the Eocene and Oligocene boundary, and found positive results supporting Bergmann’s Rule. In the warmer climates of the Eocene, I found there were smaller-bodied Hyaenodon than during the cooler climate of the Oligocene.
Jake Butts, ’15
Sponsor: John Orcutt