Parent ungulates

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Phenacodus

In the narrower sense, a possibly natural group of fossil mammals from the Palaeogene of America , Eurasia and North Africa is called parent ungulates (Condylarthra) . In a broader sense, other groups that are not closely related to one another are included, which are assumed to be the ancestors of all later, specialized ungulates . As such, they have the original characteristics of ungulates. Also sometimes all primeval ungulates are referred to as parent ungulates.

features

The molars of the common ungulates in the broader sense have adapted from a cutting to a grinding chewing movement. They are low-crowned with several blunt humps on the crown. Due to the development of a fourth cusp, the hypoconus , the upper molars are rectangular towards the chewing surface. The trigonid of the lower molars is shortened from front to back and has a conspicuous metaconid . The difference between the molars of the common ungulates and the Zhelestidae assumed to be their ancestors, as well as between later common ungulates and some of the original ungulates is not very pronounced.

The common ungulates in the narrower sense have adapted to an increasingly plant-based diet . The premolar teeth are enlarged to different degrees and are similar to the molars. These have developed wider chewing surfaces with six tooth cusps.

In the common ungulates in the broader sense, the end links of the toe bones are elongated, not split and therefore at least at the end more hoof - like than claw-like . The limbs of the traditional ungulates in the narrower sense have adapted to a toe-walking locomotion and have well-developed hooves on each toe.

Systematics

McKenna and Bell (1997) divide the condyle into families

The parent ungulates in the broader sense also include Protungulatum , Procreodi , Acreodi and Phenacolophidae .

Edward Drinker Cope described the condylarthra in 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 later took the Periptychidae out of the condylarthra and added Meniscotherium .

George Gaylord Simpson divided the condylarthra in 1931 into the families Phenacodontidae, Meniscotheriidae (including the Pleuraspidotheriidae) and Hyopsodontidae (including the Mioclaenidae). The Periptychidae and the Tricuspiodontidae he assigned to the Amblyopoda , the Apheliscidae to the Insectivora . In 1945 Simpson divided the condylarthra into the families Hyopsodontidae (including the Mioclaenidae), Phenacodontidae, Didolodontidae, Periptychidae, Meniscotheriidae (including the Pleuraspidotheriidae) and Tricuspiodontidae.

The Phenacodontidae are usually considered to be the ancestors of the unpaired ungulates . Because of the similarities in their teeth , the Hyopsodontidae and the Mioclaenidae were named as the ancestors of the artifacts . However, deviations in the postcranial skeleton contradict this view. In addition, relationships of individual groups of the condylarth were Fasthuftieren , the trunk jumpers and Röhrenzähnern adopted.

Individual evidence

  1. ↑ a b c d Malcolm C. McKenna, Susan K. Bell: Classification of Mammals Above the Species Level . Columbia University Press, New York 1997, ISBN 0-231-11012-X (English; 631 pages; pp. 361-365).
  2. ↑ a b c d e Thomas S. Kemp: The Origin and Evolution of Mammals . Oxford University Press, New York 1995, ISBN 0-19-850761-5 (English; 331 pages; pp. 234-238).
  3. ↑ Erich Thenius: Tribal history of the ungulates . In: Rudolf Altevogt, Renate Angermann, Heinrich Dathe, Bernhard Grzimek, Konrad Herter, Detlef Müller-Using, Urs Rahm, Erich Thenius (eds.): Grzimeks Tierleben : Enzyklopädie des Tierreichs. Volume 12: Mammals 3 . Kindler-Verlag, Zurich 1972, p. 468-473 (German).
  4. ^ A b George Gaylord Simpson: The Principles of Classification and a Classification of Mammals . In: Bulletin of the American Museum of Natural History . tape 85 . New York 1945 (English; 350 pages; pp. 123-124, p. 234).
  5. ↑ George Gaylord Simpson: A New Classification of Mammals . In: Bulletin of the American Museum of Natural History . tape 59 , 1931, pp. 259-293 (English; p. 269, p. 279).
  6. ↑ Jeremy J. Hooker: Perissodactyla . In: Kenneth D. Rose, David Archibald (Eds.): The Rise of Placental Mammals . Johns Hopkins University Press, Baltimore / London 2005, ISBN 0-8018-8022-X , pp. 199-214 (English; p. 202).
  7. ↑ Jessica M. Theodor, Kenneth D. Rose, Jörg Erfurt: Artiodactyla . In: Rose and Archibald (eds.): The Rise of Placental Mammals . Johns Hopkins University Press, Baltimore / London 2005, ISBN 0-8018-8022-X , pp. 215-233 (English; pp. 225-226).
  8. ↑ Emmanuel Gheerbrant, Daryl P. Domning, Pascal Tassy: Paenungulata (Sirenia, Proboscidea, Hyracoidea and Relatives . In: Rose and Archibald (Eds.): The Rise of Placental Mammals . Johns Hopkins University Press, Baltimore / London 2005, ISBN 0 -8018-8022-X , p. 84-105 (English; p. 101)).
  9. ↑ Patricia A. Holroyd, Jason C. Mussell: Macroscelidea and Tubulidentata . In: Rose and Archibald (eds.): The Rise of Placental Mammals . Johns Hopkins University Press, Baltimore / London 2005, ISBN 0-8018-8022-X , pp. 71-83 (English; pp. 75-76, pp. 77-78).