Afrotheria

Abstract

Elephants and sea cows and tenrecs; hyraxes and aardvarks and sengis and golden moles. What do these very divergent and different looking mammals have in common? They are each other's closest living relatives, and all belong to the placental mammal clade Afrotheria ('African beasts'), which is one of the four major clades of placental mammals along with Xenarthra (anteaters, sloths, armadillos), Euarchontoglires (e.g. rodents, rabbits, primates), and Laurasiatheria (e.g. bats, carnivorans, odd-toed and even-toed ungulates) (Figure 1). Unlike many animal groups that were recognized and named long ago based on anatomical features, the Afrotheria emerged as a natural clade only in the 1990s when molecular techniques were applied to the problem of placental mammal classification. The recognition of Afrotheria represents a triumph of molecular phylogenetics and brings together a fantastically diverse assemblage of placental mammals with widely disparate ecological and morphological adaptations. Although Afrotheria was not previously proposed based on studies of anatomical characters, additional support for the monophyly of this clade comes from geography and the fossil record. Specifically, the six extant orders in Afrotheria share with each other early fossil representatives that are known from Africa or along the margins of the ancient Tethys Sea, hence Afrotheria.