Trigonias

This article is about the extinct rhinoceros. For the bivalves, see Trigoniidae.

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. Its front legs had five toes (as contrasted with three in modern rhinos), the fifth of which was vestigial.^[5]

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

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

Cladogram after Lu, Deng and Pandolfi, 2023:^[7]

Rhinocerotidae	Trigonias Ronzotherium Epiaceratherium Diceratherium Molassitherium Skinneroceras Aceratheriinae (including Teleoceratini) Protaceratherium Menoceras Rhinocerotinae (modern rhinoceroses) Elasmotheriinae