Trigonias (Greek: "triangular" (trigonos), "ias" [denotes possession][3]) is an extinct genus of rhinoceros 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. Its front legs had five toes (as contrasted with three in modern rhinos), the fifth of which was vestigial.[5]

Temporal range: late Eocene[1]
Trigonias osborni.jpg
T. osborni
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Family: Rhinocerotidae
Genus: Trigonias
Lucas, 1900
Type species
Trigonias osborni
  • T. osborni
  • T. wellsi
  • Procaenopus Figgins, 1934[2]

A specimen of T. osborni was estimated to have a weight of about 391 kilograms (862 lb).[6]


  1. ^ Prothero, 2005, p. 184.
  2. ^ a b Prothero, 2005, pp. 35-37.
  3. ^ "Glossary. American Museum of Natural History". Archived from the original on 20 November 2021.
  4. ^ Prothero, 2005
  5. ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 264. ISBN 1-84028-152-9.
  6. ^[dead link]


  • Prothero, Donald R. 2005. The Evolution of North American Rhinoceroses. Cambridge University Press, Cambridge, 218 pp. ISBN 0-521-83240-3