The 30 currently recognized living species of pika (Ochotonidae: Genus Ochotona) comprise approximately one-third of all lagomorphs. The Leporidae, in contrast, contains 32 species of hare (Genus Lepus) and 29 species of rabbit (multiple genera; Hoffmann and Smith 2005). Both traditional (morphological) and molecular evidence indicates that the Ochotonidae separated from the Leporidae during the Oligocene, approximately 37 Mya. The Ochotonidae originated in Asia, but had spread to North America by the late Oligocene. Throughout their Holarctic range, and even extending into northern Africa, pikas differentiated and became quite diverse during the Miocene. Modern pikas (Ochotona) first appeared in Asia during the early Pliocene and spread to North America by the mid-Pliocene. The only two pika genera to appear in historical times, Prolagus and Ochotona, appeared in Europe by the late Pliocene. Following the extinction of Prolagus, Ochotona became the only living representative of the family that had flourished with as many as 25 fossil genera (Dawson 1967; Erbajeva 1988, 1994).
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