Afrotheria

Various members of the Afrotheria

• Röhrenzähner ( Tubulidentata )
• Elephant shrews ( Macroscelidea )
• Hyrax ( Hyracoidea )
• Manatees ( Sirenia)
• Proboscidea ( Proboscidea )
• Tenrekartige ( Afrosoricida )

The Afrotheria are a molecular genetic specified superorder within the subclass of the higher mammals. They comprise about 80 species. The outward -looking rather inhomogeneous group together the phylogenetic origin from Africa. Apart from the Asian elephant, a Hyrax - type and manatees this continent is still their habitat today. In the late Cretaceous period have become the Afrotheria in Africa, to which they were initially limited, separated from their sister group, the Exafroplacentalia ( Xenarthra and Boreoeutheria ).

Features

This group of mammals is very diverse and includes water dwellers such as the manatees, anteaters like the aardvark or giants like the elephants. The smallest belonging to Afrotheria animal is the Small Langschwanztenrek ( Microgale parvula ) with a weight of only 5 g; the African elephant (Loxodonta africana ), however, with a weight of up to 5 tons, the largest land mammal. Of the genetic characteristics that define the group apart, the most striking common feature is the elongated, sensitive to the touch and often movable snout. It is unclear, however, whether this similarity is not simply a result of convergent evolution. In addition, the group of animals is characterized by some of "primitive" traits she shares with primitive animal groups, such as the monotremes. Thus, the testes of males of many Afrotherier lie in the abdominal cavity and the thermoregulation is poorly developed in many species. But the latter can also be related to the fact that they come from warm climates.

Phylogeny

With the breakup of the southern United Gondwana in the Cretaceous period about 105 million years ago, the Afrotheria have probably developed from all other groups of higher mammals separately. Their common ancestor was probably a forest of live insects or herbivores. For many mammalian groups that developed at the same time on the northern continent Laurasia large, the Afrotheria brought forth ecological counterparts. So the Tenrekartigen similar to insectivores ( for example, the golden moles the moles ), the manatees have in their Body parallels to whales and seals, the hyrax same marmots.

As before about 30 to 40 million years ago by the proximity of Africa to Europe and Asia again picked up the isolated situation in Africa, migrated many groups of mammals from Eurasia to Africa and on the other hand poured some Afrotherier how the elephants and hyraxes, turn out to the northern to colonize continents.

System

The Afrotheria include six very different looking systems:

• The Röhrenzähner ( Tubulidentata ) with a kind, the aardvark,
• The elephant shrews ( Macroscelidea ) with 15 species,
• The hyrax ( Hyracoidea ) with 6 species,
• The manatees ( Sirenia ) with 4 species,
• The Proboscidea ( Proboscidea ), the sole extant representative of the elephants ( Elephantidae ) 3 are species and
• The Tenrekartigen ( Afrosoricida ) with 51 species, which continues in golden moles ( Chrysochloridae ) and tenrecs ( Tenrecidae ) divide.
• The extinct around 1,000 years ago Bibymalagasia, grave animals from Madagascar, which are sometimes referred to as Malagasy aardvark, and the rhinoceros -like Embrithopoda and the amphibious Desmostylia likely to belong to the Afrotheria.

Hyraxes, manatees and elephants are sometimes grouped together as Paenungulata due to their close relationship.

The representatives of this group carry in their genomes specific retroposons, so-called African Ines, who occupy the togetherness. Also confirm recent DNA sequence analyzes das.