Afrotheria (/æfroʊˈθɪəriə/ from Latin Afro- "of Africa" + theria "wild beast") is a clade of mammals, the living members of which belong to groups that are either currently living in Africa or of African origin: golden moles, elephant shrews (also known as sengis), tenrecs, aardvarks, hyraxes, elephants, sea cows, and several extinct clades. Most groups of afrotheres share little or no superficial resemblance, and their similarities have only become known in recent times because of genetics and molecular studies. Many afrothere groups are found mostly or exclusively in Africa, reflecting the fact that Africa was an island continent from the Cretaceous until the early Miocene around 20 million years ago, when Afro-Arabia collided with Eurasia.
Because Africa was isolated by water, Laurasian groups of mammals such as insectivores, rodents, lagomorphs, carnivorans and ungulates could not reach Africa for much of the early to mid-Cenozoic. Instead, the niches occupied by those groups on the northern continents were filled by various groups of afrotheres via the process of convergent evolution. The small insectivorous afrotheres such as elephant shrews, golden moles, and tenrecs filled the niches of insectivores, the hyraxes filled the roles of rodents and lagomorphs, the aardvarks filled the roles of various medium size ant-eating mammals (anteaters, armadillos, pangolins, echidnas, numbats, etc.) found on other continents throughout the Cenozoic, and proboscideans (elephants and their relatives) filled the roles of large herbivores such as hippos, camels, rhinos, and tapirs. The sirenians developed aquatic body plans and started spreading to other parts of the world by water (evolving convergently with the other groups of marine mammals such as cetaceans and pinnipeds). In addition to their similarity with Laurasian mammals in North America, Europe, and Asia, many afrotheres also exhibit convergent evolution with groups of mammals that evolved and lived exclusively in South America, which was also an island continent for much of the Cenozoic.
The common ancestry of these animals was not recognized until the late 1990s.[1] Historically, the Paenungulata had been linked to the true ungulates (particularly the Perissodactyls); the golden mole, tenrecs, and elephant shrews with the traditional (and polyphyletic/incorrect) taxon Insectivora; and the aardvarks with the pangolins and the xenarthrans within the invalid taxon Edentata. Continuing work on the molecular[2][3][4] and morphological[5][6][7][8]diversity of afrotherian mammals has provided ever increasing support for their common ancestry.
The afrotherian clade was originally proposed in 1998[1] based on analyses of DNA sequence data. However, previous studies had hinted at the close interrelationships among subsets of endemic African mammals; some of these studies date to the 1920s[9] and there were sporadic papers in the 1980s[10] and 1990s.[11][12][13] The core of the Afrotheria consists of the Paenungulata, i.e., elephants, sea cows, and hyraxes, a group with a long history among comparative anatomists.[14][15] Hence, while DNA sequence data have proven essential to infer the existence of the Afrotheria as a whole, and while the Afroinsectiphilia (insectivoran-grade afrotheres including tenrecs, golden moles, sengis, and aardvarks) were not recognized as part of Afrotheria without DNA data, some precedent is found in the comparative anatomical literature for the idea that at least part of this group forms a clade. The Paleocene genus Ocepeia, which is the most completely-known Paleocene African mammal and the oldest afrotherian known from a complete skull, shares similarities with both Paenungulata and Afroinsectiphilia, and may help to characterize the ancestral body type of afrotherians.[16]