Lava mouse

The Lava mouse is an extinct endemic rodent from the Canary Islands, Spain. It is the only species in the genus Malpaisomys.

The Lava mouse is known from Holocene and Pleistocene deposits in the eastern Canary Islands, including Fuerteventura, Lanzarote and nearby islets. It became extinct during prehistoric times, probably because of the arrival of humans and the livestock they brought with them.

A study of its skeletal characteristics suggested that the Lava mouse lived in fissures opened in the lava fields. The morphology of its teeth indicates that is was a herbivore.

Its evolutionary relationships are unresolved due to its fairly generic morphology. Rodents on islands generally increase in size during the course of their evolution; the lava mouse was fairly small for an insular rodent. Thus, it is more likely than not that is evolved from small Pliocene mainland genera Paraethomys, Occitanomys, or relatives thereof, than being a later derivative of the Deomyinae.

The rodent owes it name Malpaisomys to the Spanish word malpais, meaning "badlands", denoting the lava fields where its fossil remains are sometimes found in cavities.