Geographic variation in the diet of hypsodont herbivores from the Rancholabrean of Florida

Classifying the diet of ancient animals is important for understanding biological phenomena such as resource partitioning and the evolution of particular environments. Focusing on Bison, Equus, and Mammuthus from three geographical areas of Florida (north, central, and south) during the Rancholabrean, this study uses values of stable carbon isotope composition of tooth enamel carbonate collected from the literature to determine dietary variability, and whether hypsodonty and comparisons with modem analogs accurately represent the scope of forage taxa could utilize. Carbon isotope values show no significant differences in diet between Bison, Equus, and Mammuthus within any of the three designated geographic areas of Florida. The data do show significant differences in diet for Bison between north Florida and south Florida, for Equus between north Florida and south Florida and between central Florida and south Florida, and for Mammuthus between central Florida and south Florida. These results suggest floral differences among the geographic areas of Florida. Mean delta(13)C values for the taxa suggest that each was an intermediate feeder with a strong preference for grasses and sedges. Comparisons of diet in this study with those based on modem analogs and hypsodonty indicate that both techniques may accurately represent a taxon's average diet. However, the range in delta(13)C values observed in individuals extended from strict C-4 feeding to strict C-3 feeding and suggests a range in diet from grazing to browsing. This wide range in apparent diet indicates that multiple specimens are required to accurately interpret the feeding strategy of taxa and the relevance of the diet of animals as an indicator of environment in which they lived. (C) 2004 Elsevier B.V. All rights reserved.