A Brief History and Overview of Rhinos

The family Rhinocerotidae has had a glorious history. Since the first rhinoceros appeared about 50 million years ago, the rhino family has enjoyed abundance and diversity, with many different species that assumed a wide variety of forms and occupied a broad range of niches often associated with other kinds of animals today. Some extinct rhinos had horns; others did not. Some rhinos appeared and acted like horses, others like hippos, some like tapirs, at least one like a small elephant, and several even like giraffes. Indeed, the largest land mammal that ever lived was a rhino.

Moreover, rhinos have not always been confined to Africa and Asia. During most of the last 50 million years, they also inhabited Europe and particularly North America. Rhinos were the most common of the large herbivores in North America for 40 million years and became extinct only because of drastic climatic changes about 5 million years ago. Today, five rhino species survive: three species in Asia and two in Africa.

​

In many ways, rhinos are typical ungulates. Ecologically, they function as primary consumers or herbivores, and like most ungulates, their weapons are primarily defensive rather than offensive. Rhinos generally inhabit savannahs, shrubby regions and forests in tropical and subtropical regions. Moreover, they are usually restricted to areas in which a frequent trip to water or mud holes is possible. Mud wallowing is especially effective in accelerating heat loss, as mud is slow to dry and absorbs body heat in the process. A thick coating of mud also helps protect against insects and parasites and keeps skin supple.

​

Generally speaking, rhinos require large individual areas because of their size and daily nutritional requirements. Most are fairly territorial, defending their home ranges to ensure adequate food and minimal reproductive competition. Territories are often marked with urine or dung, as rhino vision is poor but olfactory abilities are well-developed. Flakes of skin left on trees used as rubbing posts, as well as dried mud that falls from the skin, also carry individual scents and thus help establish territorial boundaries. Wide variation does exist, however, among the rhino species with regard to the size of individual ranges, the degree of territoriality, and social organization.

​

General species descriptions are provided in books such as "Rhinos of the World" (Owen-Smith, 1975; Kingdon, 1979; Laurie, 1982; Estes, 1991; Nowak, 1991; Dinerstein, 2003; Wilson and Mittermeier, 2011). The species descriptions included in the following chapters are summaries; specific ecological studies may cite data that differ slightly from these general descriptions. Word-origin information was obtained from Borror (1960).