Rhinocerotoidea

Rhinocerotoidea is a superfamily of perissodactyls which includes the living rhinoceroses and their extinct relatives. In addition to rhinoceroses (Rhinocerotidae), Rhinocerotoidea also comprises at least three extinct families: the Amynodontidae, Hyracodontidae, and Paraceratheriidae. The relationships between the different groups are not well resolved, and two additional extinct families are sometimes recognized, the Eggysodontidae and Forstercooperiidae. Extinct non-rhinocerotid members of the group are sometimes considered rhinoceroses in a broad sense. Although the term 'rhinoceroses' is sometimes used to refer to all of these, a less ambiguous vernacular term for this group is 'rhinocerotoids'. Rhinocerotidae are sometimes called "true rhinoceroses" to distinguish them from other rhinocerotoids. Rhinocerotoidea has traditionally been divided into three families: the extant Rhinocerotidae (true rhinoceroses) and the extinct Amynodontidae (swamp rhinoceroses) and Hyracodontidae (running rhinoceroses). Phylogenetic analyses often recover the traditional Hyracodontidae as paraphyletic; the giant paraceratheres, historically considered part of the family, are therefore generally recognized as the distinct family Paraceratheriidae. Whether additional families of rhinocerotoids are recognized depends on the analysis. Historically, the basal rhinocerotoid Hyrachyus and similar forms have sometimes been placed in a family named Hyrachyidae, though recent analyses do not recover Hyrachyus in a consistent position or group.