giant-sloth

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Megatherium americanum - The Giant Ground Sloth

The skeleton of Megatherium set up in the London Natural History Museum, and a depiction of a possibility of Megatherium behavior in life.

Though the population was already decreasing when the first humans arrived in South America, the disappearance of the Giant Sloth was helped along by the new immigrants. Using mammoth-hunting skills, this large and lumbering creature was an ideal kill for a human tribe. It was one of the many Pleistocene megafauna that went extinct during the Quaternary extinctions.

Extinct monsters. H. N. Hutchinson, 1896.

Humans Blamed for Extinction of Mammoths, Mastodons & Giant Sloths, in New Study

by Stephanie Pappas

The latest volley in a long-running debate over why woolly mammoths, giant sloths, mastodons and cave lions died out worldwide suggests that humans are to blame.

A new global look at the extinctions of large mammals over the past 130,000 years finds that the loss of species correlates more closely with the arrival of humans than with changes in climate, which some studies have cited as a possible culprit.

Nonetheless, the paper is unlikely to settle the debate over what really caused the Quaternary extinction, a die-off of large mammals worldwide at the end of the Pleistocene epoch about 12,000 years ago. It is, however, one of the first fine-grained, yet global, look at how and when species died.

"The evidence really strongly suggests that people were the defining factor," said study leader Chris Sandom, co-founder of the consulting firm Wild Business Ltd., who completed the work as a postdoctoral researcher at Aarhus University in Denmark…

(read more: Live Science)

image: Jonathan S. Blair/National Geo

The Strangely Jointed MEGATHERIUM AMERICANUM 
Art by ~IRIRIV  
Lived 1.9 million - 8,000 years ago

[Source for the following:  BBC Science and Nature]

Megatherium was a massive ground sloth, covered in long dark hair. It had huge claws, and weighed almost a much as an elephant. Fossilized footprints show that it often walked on its hind legs, although there is much debate as to what it looked like when it did.

Megatherium are herbivorous. They mainly browsed vegetation in woodlands and grasslands but possibly scavenged meat too.

The South American species is known from many skeletons, sets of fossilized footprints and even dung and hair. Finds have come from as far north as Texas and as far south as Argentina.

Ground sloths are members of the superorder Xenarthra [“strange joints”], a group of placental mammals which includes modern tree sloths, anteaters and armadillos as well as the extinct glyptodonts.

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Megatherium

… was a genus of elephant-sized ground sloths endemic to Central and South America that lived from the late Pliocene through the end of the Pleistocene. Megatherium was one of the largest land mammals known, weighing up to 4 tonnes and up to 6 m (20 ft) in length from head to tail. It is the largest known ground sloth, as big as modern elephants and would have only been exceeded in its time by a few species of mammoth.

Although it was primarily a quadruped, its footprints show that it was capable of assuming a bipedal stance. This sloth, like a modern anteater, walked on the sides of its feet because its claws prevented it from putting them flat on the ground. Megatherium species were members of the abundant Pleistocene megafauna, large mammals that lived during the Pleistocene epoch…

(read more: Wikipedia)             (images: T - Dmitry Bogdanov; B - Ballista)

"Great Beast" (Megatherium) skeleton, from George Shaw’s Zoological Lectures delivered at the Royal Institution, 1800. 

Megatherium americana was one of the few species of South American megafauna to not die out soon after the Great American Interchange at the beginning of the Pliocine era, and there’s evidence that it was encountered and hunted by early humans, especially after it expanded northwards into southern North America.

The size of a bull elephant, Megatherium were largely quadrupeds, but could use their massive tail as a tripod-like base to allow themselves to stand on their hind legs and pull down the choicest branches of leaves. Their somewhat smaller (rhino-sized) ancestor Promegatherium is believed to be a direct ancestor of both Megatherium and modern-day sloths. 

Giant Sloth Dung (Pleistocene epoch)

The giant ground sloth (Eremotherium rusconi) is an ancient relative of living tree sloths, armadillos and anteaters. It lived during the Pleistocene Epoch (2.58 million years ago – 12,000 years ago) and stood 20 feet tall on its hind legs, using its huge claws to grasp tree limbs and scrape the bark off tree trunks for meals.

We know this creature ate leaves, bark and twigs because we have fossil dung, or “coprolites,” from giant ground sloths. Sometimes conditions are so dry that the dung can be preserved for thousands of years with little change. In April 1941, this fossil dung was collected by Smithsonian curator Remington Kellogg at Rampart Cave in the Grand Canyon. It is estimated to be 100,000 years old.

For more info, visit http://paleobiology.si.edu/LVF/html/pageTwelve.htm

(text/photo: Smithsonian)