Pecora

Pecora is an infraorder of even-toed hoofed mammals with ruminant digestion. Most members of Pecora have cranial appendages projecting from their frontal bones; only two extant genera lack them, Hydropotes and Moschus. The name "Pecora" comes from the Latin word pecus, which means "cattle". Although most pecorans have cranial appendages, only some of these are properly called "horns", and many scientists agree that these appendages did not arise from a common ancestor, but instead evolved independently on at least two occasions. Likewise, while Pecora as a group is supported by both molecular and morphological studies, morphological support for interrelationships between pecoran families is disputed. Evolutionary history The first fossil ruminants appeared in the Early Eocene and were small, likely omnivorous, forest-dwellers. Artiodactyls with cranial appendages first occur in the early Miocene. The appearance of Pecora during the Miocene suggests that its rapid diversification may correspond to the climate change events of that epoch. It is likely that the antelopes, giraffids, and pronghorns evolved in an open environment while the cervids, including the caribou, evolved in a woodland habitat. The type of gallop in Pecorian species is shown to be closely related to their environment and anatomy, where light Pecorian species use both flexed and extended suspensions in their fast gallops. The white-tail and mule-deer have been observed to primarily use the extended suspension, since in this phase of their gallop they leap over bushes and logs that are present in their brush environment. However, heavy Pecorian species do not use extended suspensions as most have backs that slope downward with shorter hind legs. Taxonomy and classification Pecora is an infraorder within the larger suborder Ruminantia, and is the sister clade to the infraorder Tragulina (of which Tragulidae is the only surviving family).