Trigonias
| Trigonias | |
|---|---|
| |
| T. osborni | |
Scientific classification 
| |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Perissodactyla |
| Family: | Rhinocerotidae |
| Genus: | †Trigonias Lucas, 1900 |
| Type species | |
| †Trigonias osborni | |
| Species[2] | |
| |
| Synonyms | |
| |
Trigonias (Greek: "triangular" (trigonos), "ias" [denotes possession][3]) is an extinct genus of rhinocerotid from the late Eocene (Chadronian) some 35 million years ago of North America.[4]
Description
[edit]Trigonias was about 2.1 metres (6 ft 11 in) long and, despite lacking horns, looked a lot like modern rhinos. The front feet bore 4 toes (as contrasted with three in modern rhinos), the fifth of which was entirely reduced.[5] The median digit was already the largest, whilst the second and the fourth formed a symmetrical pair. The hind feet had only 3 digits. [6]
The shape of the anterior incisors in the upper jaw of Trigonias assume a chisel-like shape. The other 2 incisors are less derived. Trigonias also bore a reduced upper canine, unlike most rhinocerotids. In the lower jaw, the second incisor grew large and tusk-like, and there was no canine. Trigonias also had small premolars when compared to the molars. The dental formula of Triognias was 3,1,4,33,0,4,3 × 2 = 42.[6]
A specimen of T. osborni was estimated to have a weight of about 391 kilograms (862 lb).[7]
Cladogram after Lu, Deng and Pandolfi, 2023:[8]
| Rhinocerotidae |
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Notes
[edit]- ^ Prothero, 2005, p. 184.
- ^ a b Prothero, 2005, pp. 35-37.
- ^ "Glossary. American Museum of Natural History". Archived from the original on 20 November 2021.
- ^ Prothero, 2005
- ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 264. ISBN 1-84028-152-9.
- ^ a b Scott, William Berryman (1913). A history of land mammals in the western hemisphere. Smithsonian Libraries. New York, The MacMillan Company.
- ^ Paleobiology Database
- ^ Lu, Xiao-Kang; Deng, Tao; Pandolfi, Luca (2023-02-16). "Reconstructing the phylogeny of the hornless rhinoceros Aceratheriinae" (PDF). Frontiers in Ecology and Evolution. 11. doi:10.3389/fevo.2023.1005126. ISSN 2296-701X.
References
[edit]- Prothero, Donald R. 2005. The Evolution of North American Rhinoceroses. Cambridge University Press, Cambridge, 218 pp. ISBN 0-521-83240-3
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