Teleoceras (Greek: "perfect" (teleos), "horn" (keratos)^[4]) is an extinct genus of rhinocerotid. It lived in North America during the Miocene and Pliocene epochs during the Hemingfordian to the end of Hemphillian from around 17.5 to 4.9 million years ago.^[5][6] It grew up to lengths of 13 feet (4.0 meters) long.^[7]

Quick Facts Scientific classification, Type species ...

Teleoceras Temporal range: Barstovian-Hemphillian ~15.97–4.9 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Specimen at the Natural History Museum of LA
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Perissodactyla
Family:	Rhinocerotidae
Subfamily:	†Aceratheriinae
Genus:	†Teleoceras Hatcher, 1894
Type species
†Teleoceras major
Species[1]
†T. aepysoma †T. aginense †T. americanum †T. brachyrhinum †T. hicksi †T. fossiger †T. guymonense †T. major †T. medicornutum †T. meridianum †T. proterum
Synonyms
†Mesoceras (Cook, 1930)[2] †Paraphelops Lane, 1927[3]

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Teleoceras had much shorter legs than modern rhinos, and a barrel chest, making its build more like that of a hippopotamus than a modern rhino. Based on this description, Henry Fairfield Osborn suggested in 1898 that it was semi-aquatic and hippo-like in habits. This idea persisted for about a century, but has recently been discounted by isotopic evidence.^[6] Some species of Teleoceras have a small nasal horn, but this appears to be absent in other species.^[8] Teleoceras has high crowned (hypsodont) molar teeth, which has historically led to suggestions that the species were grazers. Dental microwear and mesowear analysis alternatively suggest a browsing or mixed feeding (both browsing and grazing) diet.^[9]

Teleoceras is the most common fossil in the Ashfall Fossil Beds of Nebraska. In fact, its remains were so numerous and concentrated that the building housing the greatest concentration of Ashfall fossils is called the "Rhino Barn". Most of the skeletons are preserved in a nearly complete state. One extraordinary specimen includes the remains of a Teleoceras calf trying to suckle from its mother.^[10]

Teleoceras went extinct in North America alongside Aphelops at the end of the Hemphillian, most likely due to rapid climate cooling, increased seasonality and expansion of C4 grasses, as isotopic evidence suggests that the uptake of C4 plants was far less than that in contemporary horses.^[6] The Gray Fossil Site in northeast Tennessee, dated to 4.5-5 million years ago, hosts one of the latest-known populations of Teleoceras, Teleoceras aepysoma.^[11]