Meeting Abstract
P2.104 Monday, Jan. 5 The evolutionary response of tooth-row morphology to habitat shifts in artiodactyl mammals COOPER, J.M.*; MARCOT, J.D.; Univ. of Illinois; Univ. of Illinois cooper5@illinois.edu
Artiodactyls have experienced dramatic environmental changes throughout their history, and their evolutionary response is recorded in a rich fossil record. Previous studies specify numerous skeletal and dental correlates of habitat use in living artiodactyls. Unfortunately, these traits often require fairly complete skulls or elements not commonly preserved as fossils. Habitat proxies from commonly preserved elements are required to better understand the evolutionary response of artiodactyls to environmental change. The ratio of the length of the premolar row to that of the molar row has long been cited to distinguish open and closed environment artiodactyls. Open-environment taxa are expected to have proportionally longer molar rows to increase the grinding area for coarse fodder. We measured lower teeth of 101 living artiodactyl species (242 individuals) with known habitats. We performed discriminant function analysis to discriminate species from open and closed environments. The simple ratio of the lengths of the premolar and molar rows discriminated these groups nearly as well as more complicated functions. Specifically, those with relatively shorter premolar rows were found to inhabit open environments. By itself, this result does not entail a strong evolutionary correlation between habitat and morphology. We took a comparative approach to determine the evolutionary response, in which we reconstructed both this ratio and habitat use on an existing phylogeny of artiodactyls. We then compared the morphologic change that accompanied evolutionary shifts in habitat use. Shifts to more closed environments were typically accompanied by increases in the relative length of their premolar rows, and the distribution of changes were significantly different than those observed in shifts to more open environments.
