Condylarth

As Stammhuftiere ( condylarths ) a potentially natural group of fossil mammals from the Paleogene of America, Eurasia and North Africa is in the narrower sense. In a broader sense more, not more closely related groups to be accounted for, which are presumed to be ancestors of all later specialized ungulates. As such, they have the original features of the ungulates. Also all Urhuftiere sometimes referred to as Stammhuftiere.

Features

The molars of Stammhuftiere in the broader sense have adapted from a cut to a refining chewing motion. They are more obtuse niederkronig with bumps on the crown. Through the development of a fourth cusp, the Hypoconus, the upper molars to the occlusal surface toward rectangular. Trigonid the lower jaw teeth is shortened from front to back and carrying a striking Metaconid. However, the difference between the molars of the Stammhuftiere and Zhelestidae adopted as their ancestors as well as between later Stammhuftieren and some original ungulates is not pronounced.

The Stammhuftiere in the narrower sense have adapted to an increasingly plant-based diet. The Vorbackenzähne vary greatly enlarged and resemble the molars. These have developed broader occlusal surfaces with six cusps.

The Stammhuftieren in a broader sense, the end members of the toe bones are elongated, not degraded, so at least at the end rather than hoof - like claws. The limbs of the Stammhuftiere in the narrower sense have adapted to a toe transitions generic locomotion and possess well-developed toe on each hoof.

System

McKenna and Bell (1997 ) divide the condylarths in the Family

• Hyopsodontidae (including Tricuspiodontidae and Apheliscidae )
• Mioclaenidae (including Pleuraspidotheriidae )
• Phenacodontidae (including Meniscotheriidae and Almogaveridae )
• Periptychidae,
• Peligrotheriidae and
• Didolodontidae.

The Stammhuftiere in a wider sense also include Protungulatum that Procreodi that Acreodi and Phenacolophidae.

Edward Drinker Cope described the condylarths 1881. In the description, he relied mainly on Phenacodus and on Periptychus, Anisonchus, Mioclaenus and Tetraclaenodon. Cope, Henry Fairfield Osborn and Charles Earle and William Diller Matthew took the Periptychidae later from the condylarths out and added Meniscotherium.

George Gaylord Simpson divided the condylarths 1931 in the families Phenacodontidae, Meniscotheriidae (including Pleuraspidotheriidae ) and Hyopsodontidae (including Mioclaenidae ). The Periptychidae and Tricuspiodontidae he ordered the Amblyopoda to that Apheliscidae the Insectivora. 1945 Simpson told the condylarths in the families Hyopsodontidae (including Mioclaenidae ) Phenacodontidae, Didolodontidae, Periptychidae, Meniscotheriidae (including Pleuraspidotheriidae ) and Tricuspiodontidae.

The Phenacodontidae are usually regarded as ancestors of the Perissodactyla. Due to similarities of the dentition and the Hyopsodontidae the Mioclaenidae were named as ancestors of cloven-hoofed animals. However, variations in the postcranial skeleton contradict this view. In addition, phylogenetic relationships of individual groups of Stammhuftiere to Fasthuftieren, the elephant-shrews and the Röhrenzähnern were accepted.