FROM THE HORSE'S MOUTH: DENTAL MORPHOLOGY IN PLEISTOCENE SPECIES EQUUS CONVERSIDENS, EQUUS OCCIDENTALIS, AND EQUUS SCOTTI

Horses belong to the group perissodactyl, or “odd-toed”, which includes tapirs and rhinoceroses. Members in this group have a middle toe that is larger than the others. Many species of horses lived during the Pleistocene Epoch which began around 2.6 million years ago and ended 11,700 years ago. This research explores, compares, and contrasts the evolutionary changes in equine dentition for 3 species: Equus conversidens, Equus occidentalis, and Equus scotti. Dentition is the most important component for equid taxonomic identification because they are frequently the only element preserved. The markers that have been compared are hypsodonty-the length of teeth, the shape and size of the grinding teeth and whether those teeth have any kind of unified formation, and the cusp pattern of upper and lower molars. The structure of equine dentition comes from an interweaving of dentin and hard enamel which provides a distinct cusp pattern for each equine species. This paper focuses on the metacone (distobuccal), paracone (mesiobuccal), hypocone (distolingual), and protocone (mesiolingual) cusp markers in order to make inferences about each species and track evolutionary trends.