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The North American representative of this family (closely related to armadillos)
was a clumsy, heavily armored animal whose body and upper limbs were protected
by an immense, turtlelike carapace covered with horny scales. Having a six-foot-long
carapace and weighing about a ton, this animal could not have been very balletic!
Despite their size, glyptodons thrived in the tropical and subtropical regions
of Florida, South Carolina, and Texas. Glyptotherium texanum is sometimes
viewed as so highly specialized in its adaptations that local populations
could have been wiped out easily by climate change or humans. However, in
South and Central America related species of glyptodons seem to have been
successful in a wide variety of habitats -- that is, until about 10,000-11,000
years ago when all remaining species disappeared. There is no evidence that
glyptodons were hunted by humans. See also: Gillette, D. D., and C. E. Ray, 1981. Glyptodants of North America. Smithsom Contr. Paleobiol. 40:1-255. |
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Closely related to glyptodons, pampatheres were smaller and less
heavily armored. Still, they were massive: the adult Holmesina was
six feet long and weighed in excess of 500 pounds. Although pamaptheres
most likely fed on plant material for the most part, they may
have supplemented their diets with insects and other kinds of
prey, as do the living nine-banded armadillos (Dasypus novemcinctus).
Holmesina septentrionalis seems to have made its last appearance
about 10,000 years ago. No associations with humans are known.
See
also: Edmond, G., 1985. The fossil giant armadillos of North America
(Pampatheriinae, Xenarthra = Edentata). In G. Montgomery (ed.), The Evolution
and Ecology of Amadillos, Sloths, and Vermilnguas, pp. 83-93. Smithsonian
Institution Press: Washington, DC. |
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Megalonychid sloths were once widely distributed in the New World, including
the West Indies; one still survives in the forest of South America (the "ai,"
or two-toed sloth, Choloepus). They varied greatly in size, from giants
that weighed nearly a ton to species only slightly larger than the living one
(about 10 lb). The Puerto Rican sloth, at roughly 30 pounds, shows arboreal
adaptations, suggesting it was tree-dwelling (even though it is often referred
to as a "ground" sloth). Sloths survived on some West Indian islands
until about 3,000 - 4,000 years ago. Although there have been reports of sloth
bones associated with evidence of human presence, there is no indication that
the sloths were hunted.
Pleistocene sloth fur is known from several sites in the American West.
A piece of sloth skin (of Mylodon sp.) from the site of Ultima Esperanza
in Patagonia is on display at the AMNH! See also: White, J. L., 1993. Functional and phylogenetic implications of the postcranial skeleton of fossil sloths for the evolution of arboreality in tree sloths. Unpubl. PhD diss., State Univ. New York, Stony Brook. |
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Although it was the smallest of the North American "ground"
sloths, Nothrotheriops shastensis was seven- to eight-feet long
and weighed between 300 and 400 pounds. It had a small head, long
neck, prehensile lips, and walked on its knuckles with its toes
partly flexed. Thanks to the discovery of several well-preserved
specimens -- some even with skin and hair preserved -- we know
something of its external appearance. Fecal remains from the famous
Rampart Cave in Arizona indicate that it was completely herbivorous.
The range of the Shasta ground sloth stretched the length of North
America, from southern Alberta to northern Mexico. Other members
of this family were widespread in South America. All species of
megatheriids had disappeared by 10,000 - 11,000 years ago, according
to available dates.
Be sure to see a mounted specimen (the real thing!) of this species
at the AMNH! See also: McDonald, H. G., 1985. The Shasta ground sloth Nothrotheriops shastensis (Xenarthra, Megatheriidae) in the Middle Plesitocene of Florida. In G. Montgomery (ed.), The Evolution and Ecology of Amadillos, Sloths, and Vermilnguas, pp. 95-104. Smithsonian Institution Press: Washington, DC. |
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