Perhaps they used caves to secure a more stable environment in terms of humidity, as well as temperature. Why did these animals use caves? Did the caves provide shelter at night, or during the extreme heat of the day? It is possible that the sloths may have spent the day in caves and gone out to feed at night. texanus, which allows scientists to gain data about the food plants of these extinct animals.
Fossilized dung has also been excavated from many caves, including that of both Nothrotheriops shastensis and N.
Sloth skeleton skin#
Within caves, complete sloth skeletons with hair, skin and tendons still attached to the bones have been found. Conditions in caves are such that many tissues that would not normally be preserved, such as skin, nails, and other dried soft tissues, are naturally mummified and preserved. Remains of ground sloths are often found in caves or sinkholes. These ossicles across the shoulders, neck and back must have functioned like a coat of armor, adding an extra layer of protection to the thick skin and coarse hair covering the sloth's body. Pieces of dried skin with ossicles intact were found in Anza-Borrego Desert from the Harlan's Ground Sloth, Paramylodon harlani . In modern mammals, similar structures are only seen in the armadillos.
Found frequently in reptiles, these ossicles are extremely rare in mammals. Slightly larger than Megalonyx, Paramylodon is the most common ground sloth from Rancho La Brea.Ī strange anatomical feature of some ground sloths was the presence of dermal ossicles, or small nodules of bone, which formed in the skin, under the fur. Teeth of the third species, Paramylodon harlani , suggest it grazed on grasses in open habitats. They also could have squatted on their haunches to pull down higher branches off trees if needed. Ground sloths were able to stand up on their hind legs, in order to reach the leaves and twigs they wanted to eat. Megalonyx weighed nearly a ton, about the size of a bison. Megalonyx jeffersonii , on the other hand, may have specialized in eating leaves and twigs from trees such as willow and other trees of moist habitats. These animals were especially adapted to life in arid regions. Fossilized dung shows that Nothrotheriops shastensis fed on many species of plants such as yuccas, agaves, Joshua trees, globe mallows, mesquite and cacti. The three genera that lived in our region may have specialized in different food sources, thus eliminating one possible source of competition. Giant ground sloths evolved in South America around 35 million years ago, and migrated into North America, starting around 8 million years ago, with the last species arriving here during the Pleistocene. Because of this, scientists believe that ground sloths must have walked with a waddling motion. Huge claws on their feet were a striking feature.ĭue to a special modification of the foot, the weight of the animal was actually borne by the heel bone and the outside edge of the foot. Shasta ground sloths lacked front teeth and the other teeth in their tubular snout were small and blunt. Nothrotheriops was the smallest of the three, reaching upto 9 feet long (2.76 meters), with a weight up to 550 pounds (250 kg), about the size of a black bear. Three different genera of ground sloths lived in southern California until around 13,000 years ago- Nothrotheriops, Megalonyx and Paramylodon . Unlike living tree sloths, the extinct sloths were large, ponderous animals that presumably spent all their time on the ground. Their living relatives include the tree sloths, and more distantly the anteaters, and armadillos. Giant ground sloths have to be among the strangest mammals that ever walked on Earth.
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