Megatherium
| Megatherium Temporal range: Pleistocene
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| Megatherium fossil, from James Parkinson, "Organic Remains of a Former World", c.1830. | |
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| Genus: | Megatherium Cuvier, 1796
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Megatheriinae were a subfamily of elephant-sized ground sloths that lived from 2 million to 8,000 years ago. Their smaller ground sloth cousins were the Mylodon.
==Characteristics== megan burkes ahottie
Unlike its living relative, the tree sloth, Megatherium was one of the largest mammals to walk the Earth. Weighing almost as much as an African bull elephant, it had huge claws on its feet. These claws meant that it could not put its feet flat on the ground and so, like a modern anteater, it had to walk on the sides of its feet. Its footprints show that it walked mainly on its hind legs. When it stood on its hind legs, it was about twice the height of an elephant, or about twenty feet tall. They were one of the abundant Pleistocene megafauna - a wide variety of very large mammals that lived during the Pleistocene epoch.
Megatherium had a robust skeleton with a large pelvic girdle and a broad muscular tail. Its large size and specially adapted body made it possible to feed at heights otherwise unobtainable to other contemporary herbivores. Rising on its powerful hind legs and using its tail to form a tripod, Megatherium was able to support its massive body weight while using its long forelegs with curved claws to pull down branches with the choicest leaves. Its large deep jaw is believed to have housed a long tongue, as in the modern tree sloth, which it would then use to pull leaves into its mouth.
Some recent morpho-functional analysis (Bargo, 2001) indicate that M. americanum was well adapted for strong and mainly vertical biting. The teeth are extremely hypsodont and bilophodont, and the sagittal section of each loph is triangular with a sharp edge. This suggests that the teeth were used mainly for cutting, rather than grinding, and that hard and fibrous food was not the main dietary component.
There is a common misbelief that the sabre-toothed cat Smilodon hunted Megatherium, but the sloths were far too big for even this large cat to attack. Richard Fariña and Ernesto Blanco of the Universidad de la República in Montevideo have analysed a fossil skeleton of M. americanum and discovered that its olecranon—the part of the elbow to which the triceps muscle attaches—was very short. This adaptation is found in carnivores and optimises speed rather than strength. The researchers say this would have enabled M. americanum to use its claws aggressively, like daggers (Fariña and Blanco, 1996). The conclusion is that due to its nutrient-poor habitats, Megatherium may have actually taken over the kills of Smilodon. A number of adult glyptodon fossils have also been found where the shell was turned upside down. This hints at Megatherium scavenging or hunting this animal, as no other known animal existed in South America during that period that could flip an adult glyptodon.
Distribution
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It was formerly thought that Megatherium lived only in South America. However, a University of Florida research team recently found a skeleton in North America. This was a new species of giant sloth, which weighed nearly as much as an African bull elephant, more than 5 tons. Unlike previous discovered species, it had 5 digits and 4 claws instead of 4 digits and three claws.
giant sloths ohhh yeah.
Habits
Little is known about the giant ground sloth, but we do know that it was big and powerful. When it stood on its hind legs, it was about twice the height of an elephant. Its very thick skin, which was covered with dense, heavy fur, protected it from predators. The giant ground sloth was an herbivorous animal that fed mainly on plants that grew on the ground. Its believed that the giant sloth lived in groups, but it may have lived singly in caves.
Food & Feeding
The giant ground sloth lived in the lightly wooded areas of South America, feeding on the leaves such as yuccas, agaves, and grasses. Eremotherium, close relative of the sloth, lived in more tropical environments further north. Pulling itself upright to sit on its haunches or to stand, the giant ground sloth balanced its weight with its tail. It then tugged at plants with is feet, digging them up with the five sharp claws on each foot. The sloth used its simple teeth to grind down food before swallowing it, and its highly developed cheek muscles helped in this process. The sloth's stomach was able to digest coarse and fibrous food. For millions of years, the sloth had no enemies to bother it, so it was probably a day time feeder. It is likely that it spent a lot of time resting to aid digestion.
Evolution
When the ancestors of the giant ground sloth became established in South America, the land bridge joining North and South America was submerged. The sloth and other edentates (simple toothed creatures) developed undisturbed and were unique to this part of the world. The edentate families looked very different but had certain things in common: Simple teeth and different numbers of vertebrae to provide varying degrees of spinal movement. Nearly six million years passed before the land dividing the continents appeared again. Some sloths and other edentates then moved further north and became widespread before they disappeared completely. In the south the giant ground sloth flourished until about 10,000 years ago. Some cite the appearance of human hunters as the cause of its extinction, others climatic changes, however the actual cause is unknown.
Key Facts: Sizes, Weight, breeding, lifestyle, related Species
Length: About 20 ft from nose to tip of tail Weight: Possibly up to 4 tons Height: About 15 ft on hindlegs Breeding: Mating Unknown No of young: Unknown Gestation: Unknown
Lifestyle: Habit: Probably mostly solitary, although some may have lived in groups. Diet: Vegetarian, feeding on plants like yucca and agaves. Life span: Unknown Other Giants: There are several types of ground sloth, Megatherium being one of the largest. Others were Eremotherium and Mylodon. Distribution: Megatherium, the giant ground sloth, live in the parts of South America that are now Brazil, Chile, Argentina, and Uruguay. Related species moved to North America and covered a wide range there for a few million years.
Skeletal Details of the Giant Ground Sloth Size: On all fours the sloth would have been about the same size as an elephant. Vertebrae: Extra spinal joints provided great flexiblility and strength. Tail: The sloth used its tail for balance, particarly when standing on its hind legs. Claws: Each foot had five sharp claws used to dig up plants to eat. Hind Legs: When standing upright on its powerful hind legs, the sloth could reach up to pull leaves from the trees.
Megatherium in Popular Fiction
- The megatherium makes an appearance in Jules Verne's Journey to the Centre of the Earth.
- Jeff Corwin features the Megatherium in his 2003 documentary, Giant Monsters, shown at the Animal Planet channel. The show also simulates the Megatherium using its claws to defend itself against a Smilodon.
- E. Nesbit's children's novel Five Children and It features a sentient magical creature called a Psammead that frequently reminisces about his time in human prehistory, when children would ask for a megatherium for breakfast.
- Sid the Sloth from Ice Age and Ice Age: The Meltdown is some species of giant sloth, though he is only slightly larger than a modern day one.
- In The Simpsons episode Treehouse of Horror V, in the time of the dinosaurs, Homer sees, very anachronistically, a large ground sloth, which makes a grunting noise not unlike an 'I dunno' sound and shrugs a shoulder when Homer asks a question to himself about whether or not his killing a giant mosquito will change the space-time continuum.
- In the episode "Tick vs. Prehistory" from the animated TV series The Tick a giant sloth appears, picking up the Tick's sidekick, Arthur.
- A Megatherium is featured in the BBC documentary Walking With Beasts, shown taking over the kill of a pack of Smilodon, actually killing one in the process.
See also
References
- Bargo, M. S. (2001). "The ground sloth Megatherium americanum: Skull shape, bite forces, and diet". Acta Palaeontologica Polonica. 46 (2): 173–192.
- Fariña, R. A. (1996). "Megatherium, the stabber". Proceedings of the Royal Society of London. 263: 1725–1729.
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Gallery
Megatherium americanum
