An international team of scientists has discovered three unknown species of mouse lemurs, the world’s smallest primates, living in the endangered forests of Madagascar. The three new species, whose skulls are shown above, are Microcebus berthae, Microcebus sambiranensis, and Microcebus tavaratra.

Lemurs are primitive primates that live in trees and are found only on the island of Madagascar and the nearby Comoro Islands off the east coast of Africa. They have long noses, agile limbs, and piercing round eyes and can be as big as a medium-sized dog or as small as a chipmunk. There are about 40 species of living lemurs, and more than half of them are endangered, as their forest habitats are destroyed by Madagascar’s poor and rapidly growing population. Research on lemurs is important from an evolutionary standpoint because they are the most primitive of living primates.

Until a few years ago, scientists believed that only two species of mouse lemurs (the smallest of their kind) lived on the entire island. But a group of researchers including Steven Goodman of The Field Museum in Chicago, Jörg Ganzhorn of the University of Hamburg, and Rodin Rasoloarison of the University of Antananarivo in Madagascar and the Deutsches Primatenzentrum in Germany, recently completed the most detailed survey ever of mouse lemur populations in Madagascar’s western forests. Comparing the physical characteristics of mouse lemurs from 12 geographic locations, the scientists found that seven different species–including three new to science–are living where only a few were thought to exist.

Northwestern University evolutionary biologist Anne Yoder conducted an independent genetic analysis that confirmed the team’s results.