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Mon February 18, 2013
Dr. Larisa DeSantis, Vanderbilt University – Megafauna Diets and Extinction
In today’s Academic Minute, Dr. Larisa DeSantis of Vanderbilt University reveals what North America’s largest predators were eating just before they died out.
Larisa DeSantis is an Assistant Professor in the Department of Earth and Environmental Sciences at Vanderbilt University. Her research focuses on revealing the ecology and biology of ancient mammals, with a focus on assessing past responses to climate change. She earned her Ph.D. in Zoology at the University of Florida.
Dr. Larisa DeSantis – Megafauna Diets and Extinction
To this day it is a mystery as to why so many large animals went extinct approximately 12,000 years ago in North America. While changing climates and/or human overhunting have been recognized as the primary causes behind these extinctions in large herbivorous animals, it is unclear as to why giant predators including the American lion and saber-toothed cats went extinct. Prior studies have painted the picture that times were “tough” during the Pleistocene as carnivores have a higher incidence of broken teeth as compared to living carnivores in Africa, suggesting that they were desperately consuming entire carcasses due to limited food.
Our research aimed to develop another way of assessing carcass utilization or bone processing. Specifically, we examined the microscopic wear patterns left due to the processing of food in African carnivores to confirm that the microwear patterns we observe are consistent with known diets. Subsequently, we applied this method to extinct carnivores at the La Brea Tar pits in Southern California.
Based on prior tooth breakage data, we assumed we would see evidence of bone processing – especially in the American lion of which nearly one-third of all specimens have broken canines. We actually saw the exact opposite pattern. The American lion showed an avoidance of bone that is analogous to cheetahs, today.
The saber-toothed cat, previously thought to avoid bone because of its large saber like canines, appears to be most similar to the modern African lion, which at times does process bone. Further, if we look through time, we don’t see any evidence of “tough” times requiring complete consumption of carcasses, in fact the American lion actually shows the opposite pattern. Overall, we see no evidence for limited food – these carnivores were living the “good life” at least up until the very end.