Megalonyx
a.k.a. Jefferson's ground sloth

Name: Megalonyx ‭(‬Giant claw‭)‬.
Phonetic: Meg-ah-lon-ix.
Named By: Richard Harlan‭ ‬-‭ ‬1825.
Classification: Chordata,‭ ‬Mammalia,‭ ‬Xenarthra,‭ ‬Pilosa,‭ ‬Megalonychidae.
Species: M.‭ ‬jeffersonii‭ (‬type‭)‬,‭ ‬M.‭ ‬wheatleyi,‭ ‬M.‭ ‬leptostomus,‭ ‬M.‭ ‬matthisi.
Diet: Herbivore,‭ ‬possibly omnivorous.
Size: Up to‭ ‬3‭ ‬meters long.
Known locations: Across North and Central America.
Time period: Tortonian of the Miocene through to the Tarantian of the Pleistocene.
Fossil representation: Many specimens.

       This giant ground sloth may not be as famous as Megatherium,‭ ‬but it does have a presidential connection in that the name Megalonyx was proposed by Thomas Jefferson,‭ ‬although this was actually before he was president in‭ ‬1797.‭ ‬However despite Jefferson naming the first remains,‭ ‬the name Megalonyx was not formerly recognised until‭ ‬1825‭ ‬when it was officially described by Richard Harlan so that it could be a valid taxonomic listing.
       At three meters Megalonyx was towards the smaller end of the scale for giant sloths.‭ ‬Although typically a herbivore,‭ ‬analysis of several ground sloth remains indicates that giant ground sloths may have supplemented their diets with meat.‭ ‬Megalonyx may have also done this,‭ ‬possibly scavenging carrion to obtain additional nutrition that was lacking in its usual herbivorous diet.‭ ‬Here Megalonyx may have been able to use its size to bully dedicated predators into giving up their kills while Megalonyx took what it needed.
       It’s thought that giant ground sloths that had evolved in South America spread out to North America because falling sea levels combined with increased volcanic activity allowed a land bridge‭ (‬which today we call Panama‭) ‬to link the two continents together.‭ ‬This transfer of fauna worked both ways,‭ ‬and is seen as the reason why some North American animals such as Smilodon were also active in South America.

Further reading
- Third contribution to the Snake Creek Fauna. - Bulletin of the American Museum of Natural History 50:59-210. - W. D. Matthew - 1924.
- The Ground Sloth Megalonyx from Pleistocene Deposits of the Old Crow Basin, Yukon, Canada. - Arctic (Calgary, Alberta: The Arctic Institute of North America) 53 (3): 213–220. - H. G. McDonald, C. R. Harington & G. De Iuliis - 2000.
- Ancient Mitogenomes Reveal the Evolutionary History and Biogeography of Sloths. - Current Biology. 29 (12): 2031–2042.e6. - F. Delsuc, M. Kuch, G. C. Gibb, E. Karpinski, D. Hackenberger, P. Szpak, J. G. Mart�nez, J. I. Mead, H. G. McDonald, R. D. E. MacPhee, G. Billet, L. Hautier & H. N. Poinar - 2019.

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