Diversity and evolutionary trends of the Family Rhinocerotidae (Perissodactyla)

Diversity and evolutionary trends of the Family Rhinocerotidae are presented herein. The sample has a temporal range from the Middle Eocene to recent, including 41 genera and 142 species from Europe, Asia, North America, and Africa. Diversity and the first and last records have been established for each area along a temporal scale. The relative body size and weight and the gracility index of the McIII have been also analysed. The results show that the highest values in diversity and first and last records are reached in Asia. Eurasia and Africa share many taxa, while North America is more independent at generic and specific levels. Very small and very slender taxa are present in Eurasia and North America, absent in Africa. They coexist with brachypodial and generally large forms in Eurasia, whereas in North America they are replaced by large, more robust forms. From the Middle Miocene onward, middle-large sized species with intermediate gracility predominate, often together with the brachypodial ones. The latter type disappears by the Late Miocene, with just one genus remaining in Asia during the Pliocene. At this time a general decline of the Rhinocerotidae occurs, related to a major climatic change, becoming extinct in North America. By the end of the Pleistocene, rhinocerotids disappear from Europe and wide areas of Asia, but they remain in southeast Asia and in Africa, south of the Sahara.