Gregory J. Smith

The foods eaten by an organism leave evidence of their textural and geochemical properties in mammalian tissues, which can be used to reconstruct the dietary signature of modern and extinct organisms. My early PhD research used the diets of extinct megafauna to make inferences into their interactions with other species and their environment. Over the course of this work, my research group has shown that the long-held notions of mastodons as ‘browsers’ and mammoths as ‘grazers’ do not adequately capture the dietary flexibility of these taxa. Further, the consumption of similar resources in three proboscidean groups (mammoths, mastodons, and gomphotheres) in the Pleistocene led to a competitive exclusion, wherein mammoths became a dominant megafaunal organism in North America, while gomphotheres disappeared from the continent. This work has the potential to help predict what might happen in the near future as more ecologically-similar groups are forced to share habitat, and as ever-increasing land use by humans leads to shifting and contracting biogeographic ranges. I am currently extending this work to Plio-Pleistocene sites in California, Arizona and New Mexico, and plan to better document the evolution of ecologic strategies in large mammals over this critical interval in North American history. Thus far, I have found that populations of megafauna in southern California may have been able to co-exist by specializing on disparate resources, resulting in one of the largest and most diverse assemblages of megaherbivores in late Pleistocene North America.