DIETARY ADAPTATION OF SOME EXTINCT RUMINANTS DETERMINED BY PREMAXILLARY SHAPE

Extant ungulates can be divided into three dietary categories: browser s, grazers, and mixed feeders. Dietary adaptations can be differentiat ed in extant ruminants based upon analysis of premaxillary shape. This study applies methods to determine the dietary adaptations of extinct ungulates through analysis of premaxillary shapes. While browsers hav e pointed premaxillae and grazers have square premaxillae, mixed feede rs have premaxillae that are a shape intermediate to the browsers and grazers, sometimes accompanied by an indentation on either side of the incisive foramen, which results in a club-shaped premaxilla. Cranioce ras skinneri (Palaeomerycidae), Dromomeryx whitfordi (Palaeomerycidae) , Palaeotragus coelophrys, ''Palaeotragus'' primaevus, an undetermined species from the Baringo Basin of Kenya (Giraffidae), Texoceros guimo nensis (Antilocapridae), and Turcocerus grangeri (Bovidae) were found browsers; Aletomeryx gracilis (Palaeomerycidae), Bramatherium megaceph alum (Giraffidae), Cosoryx furcatus (Antilocapridae), Honanotherium sc hlosseri (Giraffidae), Samotherium boissieri (Giraffidae), Samotherium neumayri (Giraffidae), Samotherium sp. nov., Sivatherium giganteum (G iraffidae), and Synthetoceras tricornatus (Protoceratidae) were grazer s; and Merycodus necatus (Antilocapridae) and Palaeotragus rouenii (Gi raffidae) were mixed feeders.