Ungulate

Ungulates ( Ungulata ) is the collective term for several groups of mammals, in particular the Artiodactyla and Perissodactyla of. The distinction between these two main groups is old: In perissodactyls the middle toe alone bears the body weight in cloven-hoofed animals take over third and fourth toe this function.

Discussion about the ungulates as systematic unity

It is still debatable whether it as a natural systematic group are the ungulates ( monophyletic taxon ) or whether they are a motley group according to external criteria of unrelated taxa.

18th and 19th centuries

Was erected in an order of hoofed animals for the first time by Carolus Linnaeus in the 12th edition of Systema Naturae (1766). Even after Richard Owen had marked the separation of even-toed ungulates and odd-toed ungulates in the 19th century, it still went from a togetherness of these orders in a higher taxon from. In the late 19th century, the ungulates finally included the following orders:

• Röhrenzähner ( Tubulidentata )
• Hyrax ( Hyracoidea )
• Manatees ( Sirenia)
• Proboscidea ( Proboscidea )
• Odd-toed ungulates ( Perissodactyla )
• Ungulates ( Artiodactyla )

20th century

Grzimek's Animal Life asked this and a number of fossil orders in a system of five superorders:

The terms " Urhuftiere " and "Fast - hoofed animals " suggest that these are precursors to the ungulates on an evolutionary ladder, which has thus been found in pair - and odd-toed ungulates their completion. While such a view with modern systematic theory is inconsistent, there is still zoologists that prepare a monophyletic taxon Ungulata. So early in their Ungulata as " large order" ( grand order) in the systematics of McKenna and Bell in 1997. Here they include the above regulations, supplemented by the whales.

Current discussion

A possible cladogram of Ungulata in consultation with important fossil taxa might look like this:

Perissodactyla ( odd-toed ungulates )

Embrithopoda (†)

Hyracoidea ( Hyrax )

Sirenia ( manatees )

Desmostylia (†)

Proboscidea ( Proboscidea )

? Condylarths ( Urhuftiere, †)

? Tubulidentata ( Röhrenzähner )

? Dinocerata (†)

Arctostylopida (†)

Cetartiodactyla ( cloven-hoofed animals and whales)

For a long time there are doubts as to the affinities of the various taxa mentioned. The aardvark is the only living representative of the Röhrenzähner is more closely related by molecular genetic studies with any other living mammal. His line has possibly separated from the others already 90 million years ago. In contrast, the three orders of Paenungulata are indeed related to each other, but probably not with the other " ungulate " taxa. Aardvark and formerly known as "fast- hoofed " designated Paenungulata sometimes a parent taxon of Afrotheria are now assigned to that determined the molecular genetic level, but is not supported by the fossil record.

The taxon cladogram shown in the Altungulata that summarizes Perissodactyla and Paenungulata, was denied in 1997 by Graur, Duret, and Gouy. They could not detect any molecular correspondence between odd-toed ungulates and Paenungulata. Instead, they come to the conclusion that the odd-toed ungulates in fact closely related to the artiodactyls and maybe even their sister group. Both together are in turn related to the predators, but not with the pre-and fast- hoofed animals called.

State of knowledge

According to the modern view, it is therefore not very likely no taxon of hoofed animals, at least in the original compilation. Largely uncontroversial, the following taxa are each monophyletic, their relationships with each other but are still to be clarified:

• Paenungulata: elephants, sea cows, and hyraxes
• Perissodactyla: odd-toed ungulates
• Cetartiodactyla: Artiodactyla and whales

The position of the aardvark is not clear, it does not belong to these taxa.