| 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]
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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