Condylarth
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Condylarthra is an order of Paleocene mammals. One of the most characteristic, it illustrates the evolutionary level of the Paleocene mammal fauna.
When compared to today's mammals, condylarths are relatively unspecialized placental mammals. However, in comparison to their insectivorous ancestors, members of the Condylarthra show the first signs of specializing to become omnivores or even herbivores.
Since larger land-bound herbivores were absent since the extinction of the dinosaurs, this shift in diet triggered the tremendous evolutionary radiation of the condylarths that we can observe throughout the Paleocene, resulting in the different groups of ungulates (or "hoofed mammals") that form the dominant herbivores in most Cenozoic animal communities on land, except on the island continent of Australia.
Here, the term Ungulata refers to a subgroup of placental mammals that are descendants of a common ancestor, the most primitive condylarth. Among recent mammals, Paenungulata (hyraxes, elephants, aardvarks, sea cows) and whales are traditionally regarded as members of the Ungulata. Besides these, several extinct animals also belong to this group, especially the endemic South American orders of ungulates (Meridiungulata). Although many ungulates have hoofs, this feature does not define the Ungulata. Some condylarths indeed have small hoofs on their feet, but the most primitive forms are clawed.
The latest molecular and DNA research reorganised the picture of mammal evolution. The Paenungulates are no longer seen as true ungulates. The Meridiungulates might form an independent group as well. If that's the case, hooves seems to be a trait that at least three different mammal lineages acquired, completely independent from each other.
This means that the Condylarthra becomes polyphyletic: the several condylarth groups may not be related to each other at all. The best known groups are: Dinocerata (containing the well-known Uintatherium), Procreodi and Bulbulodentata. The exact taxonomic position of these groups is not known. It is believed that the Dinocerata and Procreodi are 'true' condylarths, while the Bulbulodentata might be the ancestors of the Meridiungulata, thus members of the cohort Atlantogenata.
The 'true' condylarths are seen as members of the cohort Laurasiatheria. Groups that probably descended from the condylarths are the 'true ungulates' Cetartiodactyla (containing the whales) and Perissodactyla, the Mesonychia and probably the Ferae (containing the Carnivora and Pholidota).
[edit] Taxonomy
- Family Arctocyonidae
- Family Periptychidae
- Family Hyopsodontidae
- Family Mioclaenidae
- Family Phenacodontidae
- Genus Phenacodus
- Family Didolodontidae
- Family Sparnotheriodontidae?
