Mesotherium
| Mesotherium Temporal range:
| |
|---|---|
| |
| Skull of Mesotherium cristatum | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | †Notoungulata |
| Family: | †Mesotheriidae |
| Subfamily: | † Mesotheriinae
|
| Genus: | †Mesotherium Serres, 1867 |
| Type species | |
| †Mesotherium cristatum Serres, 1857
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| Synonyms | |
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Mesotherium ("Middle Beast")
Etymology
Serres named Mesotherium so due to his belief that it was an intermediate between rodents and pachyderms (or ungulates), due to its large upper
Despite Serres' having officially named the genus Mesotherium, it was known from the late 19th century to the early 20th century under the name "Typotherium", given it by the French palaeontologist living in Argentina, Auguste Bravard;[4] under this name, Bravard sent the skull he found to Paris, which led to the family being named "Typotheriidae", and served as the basis for the order Typotheria.[1] As the name Mesotherium had been published earlier in the same year as Typotherium, Mesotherium was declared the valid name of the genus, (Simpson, 1980[4]) and Mesotheriidae the valid name of the family.[1] Nevertheless, as the rules do not apply to anything above the family, the name of the order Typotheria is still in use, but refers to a wider range of rodent-like notoungulates.[1]
Description
Mesotherium was likely the size of a small sheep, and weighed around 55 kilograms (121 lb),[1] or possibly up to 100 kilograms (220 lb), making it the largest known member of Typotheria.[5] Like most rodents, it had superficially long upper incisors, which met at the tips,[1] however, it had enamel on both the labial and lingual surfaces of the incisors, while rodents only have enamel on the labial surface.[1] The lower incisors of Mesotherium were reminiscent of those of a rabbit's.[1]
The ankle joint of Mesotherium was made up of a "ball-and-socket" arrangement between the
Mesotherium was likely fossorial, in that it dug, possibly to find food,[1][6] or to construct dens.[5]
Ecology
Mesotherium is suggested to have been a mixed feeder that likely consumed a large quantity of grasses, with its wide snout allowing for bulk feeding. In comparison to earlier mesotheriids, it probably consumed less hard food items.[5]
Chronology
The oldest known specimens of the genus date to the Early Pleistocene. The youngest known specimen of the genus dates to around 220,000 years ago during the late Middle Pleistocene.[7]
References
- ^ a b c d e f g h i j "D. Croft SA Mammals: Mesotheriidae". D. Croft. 2007-01-02. Archived from D. Croft SA Mammals: Mesotheriidae the original on 2009-12-24. Retrieved 2008-06-05.
{{cite web}}: Check|url=value (help) - S2CID 249531139.
- ^ Darwin Correspondence Project: Letter dated 20 April [1863][permanent dead link],
- ^ ISBN 0-521-59033-7Retrieved on 2008-05-02
- ^ S2CID 233684440.
- ^ a b c "Analysis of function in the absence of extant functional homologues: a case study using mesotheriid notoungulates (Mammalia)". Bruce Shockey, Darin Croft, and Frederico Anaya. Spring 2007. Retrieved 2008-07-10.[permanent dead link]
- S2CID 254913691.
Further reading
- The Origin and Evolution of Mammals (Oxford Biology) by T. S. Kemp
- Horns, Tusks, and Flippers: The Evolution of Hoofed Mammals By Donald R. Prothero, Robert M. Schoch Published 2003 ISBN 0-8018-7135-2
- Forms of Animal Life: A Manual of Comparative Anatomy By George Rolleston, William Hatchett Jackson Published 1888 Clarendon Press
- The Century Dictionary: An Encyclopedic Lexicon of the English Language By William Dwight Whitney. Published 1890 The Century Company; original from Harvard University.
- Classification of Mammals Above the Species Level: Above the Species Level By Malcolm C. McKenna, Susan K. Bell, George Gaylord Simpson. Published 1997 ISBN 0-231-11013-8
- Neanderthals Revisited: New Approaches and Perspectives By ISBN 1-4020-5844-6