Prolagus is an extinct genus of lagomorph. Over 20 species have been named, and the genus was abundant and widespread in Europe during the Neogene. However, by the end of the Middle Pleistocene, it was confined to a single species, the Sardinian pika (P. sardus), on the Corsica, Sardinia, and surrounding islands, where it survived into historical times.[3] In North Africa and Western Asia, the genus is known from the Miocene and Pliocene.[4] The scientific name may mean "before hares" or "primitive hares" (pro- meaning "before" and lagos meaning "hare"). Its taxonomy is disputed, with it either being considered a member of the family Ochotonidae, which includes living pikas, or the only member of the family Prolagidae.
Prolagus was first named by Auguste Pomel in 1853. Prolagus has been considered by most taxonomists to be a member of the pika family Ochotonidae, but distinct from living pikas, which all belong to the genus Ochotona.[5] Erbaleva in 1988 suggested it represented the only member of the monotypic family Prolagidae due to its distinct dental formula;[6] this proposal was considered invalid by Nieves López Martínez, due to the fact that many mammal families have lineages with distinct dental formulae.[5] However, many authorities such as the IUCN Red List and American Society of Mammalogists accept Prolagidae as valid.[7][8] Analysis of a partial mitochondrial genome of Prolagus sardus suggests that it is more closely related to Ochotona than to Leporidae (which contains rabbits and hares), with an estimated divergence between Prolagus and Ochotona about 30 million years ago.[9]
Prolagus is distinguished by a continuously growing dentition, a lack of a lower third molar, a trilobed second lower molar and unusually shaped premolars, with additional cusps in the lower third premolar. In comparison to modern pikas of the genus Ochotona, they have one less dorsal vertebra in the spinal column. Most species of Prolagus probably weighed around 500 grams (1.1 lb), similar to a living pika.[5] A specimen with preserved soft-tissue is known from late Miocene aged deposits from Andance in France, which shows that its overall proportions, shape of the ears and lack of tail are similar to living Ochotona.[5]