''Trigonias'' (Greek: "triangular" (trigonos), "ias"
enotes possession is an extinct genus of
rhinoceros
A rhinoceros (; ; ), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates in the family Rhinocerotidae. (It can also refer to a member of any of the extinct species o ...
from the late
Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
(
Chadronian
The Chadronian age within the North American Land Mammal Ages chronology is the North American faunal stage typically set from 38,000,000 to 33,900,000 years BP, a period of . It is usually considered to fall within the Eocene epoch. The Chadroni ...
) some 35 million years ago of
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
. ''Trigonias'' was about long and, despite lacking
horn
Horn most often refers to:
*Horn (acoustic), a conical or bell shaped aperture used to guide sound
** Horn (instrument), collective name for tube-shaped wind musical instruments
*Horn (anatomy), a pointed, bony projection on the head of various ...
s, 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
Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...
.
A specimen of ''T. osborni'' was estimated to have a weight of about .
[http://paleodb.org/cgi-bin/bridge.pl?a=basicTaxonInfo&taxon_no=52444 ]
Notes
References
*Prothero, Donald R. 2005. ''The Evolution of North American Rhinoceroses.'' Cambridge University Press, Cambridge, 218 pp.
Eocene rhinoceroses
Eocene odd-toed ungulates
Eocene mammals of North America
White River Fauna
Fossil taxa described in 1900
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