Meeting Abstract

P1.91  Sunday, Jan. 4  Durophagivores vs. mixed feeders: niche differentiation using stereoscopic dental microwear DEWAR, E.W.; Suffolk Univ. edewar@suffolk.edu

Because dental enamel preserves a record of foods recently chewed, the microwear of teeth has long been used to differentiate diets in living and extinct groups of mammals. For this work, I used a stereoscopic low-magnification method to observe enamel use-wear features of 92 species of Paleogene mammals. Most of the species sampled were from the White River Group of the American Great Plains, which are well-studied assemblages that span the Eocene-Oligocene transition. I found previously that despite substantial climatic change during the Eocene-Oligocene transition, the mammals known from the White River Chronofauna overlapped substantially in use wear when sorted into biostratigraphic zones. This work describes a distinct group of "durophagivores" within the ungulates that was recognized based on their differences in use wear with the common browsers and grazers of the time period. The durophagivores or rooters accumulated fewer but heavier scratches and many more pits than seen in more mixed-feeding species. In addition to the durophagivores present in the White River Chronofauna (particularly entelodonts and anthracotheres), I found evidence for abrasive diets in early members of several artiodactyl families and archaic groups such as "condylarths" and tillodonts. Similar evidence of abrasive parts of the diet is seen when comparing the use wear of carnivorans that chew bones as opposed to meat specialists that avoid it in their diets. In this case, skeletal elements rather than silica-based grit are likely to have caused their heavy wear. The likely source of of dietary abrasion is delimited by considering morphological differences among species’ teeth and the foods that they were likely adapted to comminute.