Dinocerata

Dinocerata
Eobasileus , drawing by Charles R. Knight
Temporal occurrence
Upper Paleocene to Middle Eocene
55 to 40 million years
Locations
North America Asia
Systematics
Synapsids (Synapsida) Mammals (mammalia) Higher mammals (Eutheria) Laurasiatheria Scrotifera Dinocerata
Scientific name
Dinocerata
Marsh , 1872

The Dinocerata are an extinct group of mammals that was common in North America and Asia from the Upper Paleocene to the Middle Eocene . Its best known representative is Uintatherium .

General

Dinocerata means "terrible horns" and alludes to the paired horns that the later representatives of this group wore on their heads. These were possibly covered with fur, as with the giraffes . The upper canines developed into large tusks - presumably a form of sexual dimorphism . In return, the upper incisors receded - in order to still be able to ingest food, they probably had a very flexible long tongue and a similar upper lip. Her physique was stocky, her legs were relatively short and strong.

The Dinocerata were among the first giant forms to develop within mammals after the dinosaurs became extinct. Early forms reached the dimensions of pigs , while the largest ones reached a length of over 3 meters and an estimated weight of up to 2.5 tons.

Finds by representatives of the Dinocerata are known from North America and Asia and are dated to the Upper Paleocene and the Eocene . Relatively little is known about their way of life, the structure of the low-crowned ( brachyodont ) molars with two high enamel ridges placed crosswise suggests a preference for soft vegetable foods ( browsing ). A semi-aquatic way of life is also being discussed.

It is unclear why these animals became extinct again relatively early (in the middle Eocene). There are no known predators or direct food competitors.

Systematics

The relationships of the Dinocerata to other mammalian taxa are largely unclear. In the past, they were assigned to the " ungulates ", but this group is likely to be a polyphylum , i.e. a thrown together group of animals that only share external characteristics with one another without being closely related. One thesis places the Dinocerata in the vicinity of the Pyrotheria and Xenungulata , two South American mammal groups that are usually counted among the South American ungulates . It could also be related to the Zhelestidae , a group of mammals from the Cretaceous period . In any case, the Dinocerata represent a specialized, relatively short-lived side branch.

The earliest representatives were Probathyopsis and Prodinoceras , which were still relatively small and did not yet have the typical horns. The most famous later genera include the gigantic representatives such as Uintatherium and Eobasileus , characterized by their bony horn formations , but also the hornless and small Gobiatherium .

literature

• TS Kemp: The Origin & Evolution of Mammals. Oxford University Press, Oxford 2005. ISBN 0198507615

Web links

Commons : Dinocerata  - collection of images, videos and audio files

Individual evidence

1. ^ ^{A b c} Walter H. Wheeler: Revision of the Uintatheres. Bulletin of the Peabody Museum of Natural History Yale University 14, 1961, pp. 1-93
2. ^ ^{A b c} William D. Turnbull: The Mammalian Faunas of the Washakie Formation, Eocene Age, of Southern Wyoming. Part IV. The Uintatheres. Fieldiana 47, 2002, pp. 1-189
3. ^ Wighart V. Koenigswald and Kenneth D. Rose: The Enamel Microstructure of the Early Eocene Pantodont Coryphodon and the Nature of the Zigzag Enamel. Journal of Mammalian Evolution 12 (3/4), 2005, pp 419-432
4. ↑ JGM Thewissen and PD Gingerich: Systematics and evolution of Probathyopsis (Mammalia, dinocerata) from the Late Paleocene and Early Eocene of Western North America. Contributions from the Museum of Paleontology The University of Michigan 8, 1987, pp. 195-219
5. ↑ Spencer George Lucas: Gobiatherium (Mammalia: Dinocerata) from the Middle Eocene of Asia: Taxonomy and biochronological Significance. Paläontologische Zeitschrift 74 (4), 2001, pp. 591-600