Ungulata

Ungulata is a historical term used to describe mammals that have hooves. The name derives from the Latin ungula, meaning “hoof.” In traditional classifications, Ungulata grouped two major orders: Perissodactyla, the odd-toed ungulates (horses, rhinoceroses, tapirs), and Artiodactyla, the even-toed ungulates (cattle, deer, goats, sheep, camels, llamas, and many other living forms).

In modern systematics, Ungulata is no longer treated as a valid clade. Molecular and morphological evidence shows that cetaceans (whales and dolphins) are nested within the broader Artiodactyla, giving rise to the clade Cetartiodactyla. Because of this, Ungulata is typically regarded as paraphyletic or obsolete in formal classifications. Some non-specialist sources still use Ungulata informally to refer to hoofed mammals excluding cetaceans, but such usage does not reflect current phylogenetic understanding.

Anatomy and ecology: Hooves are specialized keratinous structures at the tips of toes, with limb adaptations for running and support on varied terrains. Most ungulates are herbivorous, often with complex dentition and, in many subgroups, specialized digestive systems. Artiodactyla includes ruminants such as cattle, deer, and antelope, as well as non-ruminants like pigs and camels (with hippos now placed within Cetartiodactyla). Perissodactyla comprises horses, rhinoceroses, and tapirs, which differ in dentition and digestive anatomy from most artiodactyls.

Evolution and fossil record: Early ungulate-like mammals appear in the Paleocene, with diversification through the Eocene and Oligocene. The Cenozoic saw extensive radiation, leading to a wide range of sizes, ecologies, and geographic distributions among living ungulates.