Eremotherium laurillardi, a species of giant ground sloth, apparently was abundant along the Georgia coast during the Sangamonian Interglacial (~132,000 BP-~118,000 BP). Fossils of this species have been found at 7 of the 9 known coastal fossil sites of Pleistocene Age. It was really a spectacular beast growing as large as 18 feet long and weighing 6000 pounds. When it sat on its haunches, it was even taller than a mammoth. It disappeared from the state when the climate turned colder, probably some time between ~75,000 BP-~30,000 BP. The fossil record is too incomplete to determine exactly when this species succombed to the cold in this region. Eremotherium continued to exist in South America until the end of the Pleistocene. Two other species of ground sloths were better adapted to the cold and likely lived in Georgia as recently as 11,000 BP. Jefferson’s ground sloth (Megalonyx jeffersonii) and Harlan’s ground sloth (Paramylodon harlani) were able to survive subfreezing temperatures by denning in underground burrows. (See: http://markgelbart.wordpress.com/2012/10/10/some-giant-ground-sloths-dug-long-burrows/).
Size comparison between Eremotherium laurillardi and a man
Eremotherium primarily ate leaves and twigs. However, I wonder if they supplemented their diet by foraging on seaweed that washed upon the beach. Because this species frequented the coast, I’m sure they knew how to swim and may have colonized areas of the mainland or islands by crossing waterways with a depth above their head. Seaweed is high in certain minerals such as iodine and sodium that are lacking in tree leaves. Modern day tree sloths are known to obtain these nutrients by raiding human septic tanks to feed on feces. If Eremotherium ate seaweed, scientists should be able to find abrasions on their teeth from munching seaweed with sand adhering to it. The scientific literature is silent about this detail, but that may be because scientists have never looked for this evidence.
Two-toed tree sloth, Choloepus didactylus, climbing from a latrine where it just enjoyed snacking on human shit. The minerals excreted by humans supplement the diet of this species which consists of tree leaves low in sodium.
There was a genus of South America ground sloths that did gradually evolve into an increasingly aquatic existence. Five consecutive species of ground sloths in the Thalossocerus genus lived on the coast of Chile and Peru between 9 million years BP-4 million years BP. The earliest species was Thalossocerus antiquus and the last was T. yaucensis. T. antiquus had a shorter nose and abrasions on its teeth from eating seaweed with sand adhering to it. It likely foraged on the beach and in shallow water. T. yaucensis had a longer nose and no abrasions on its teeth–evidence it swam deeper into the ocean to feed upon kelp that was washed free of sand by the currents. Moreover, T. yaucensis had greater bone densisty, a characteristic found in marine mammals; and their anatomy suggests they had strong lips for plucking underwater plants. Manatees have similarly strong lips. The environment in this region then was mostly desert, so evolving the ability to subsist mostly on seaweed facilitated the survival of this species in an otherwise uninhabitable landscape. This genus became extinct at the end of the Pliocene during a major marine extinction event.
Thalassocerus sp., a marine ground sloth that lived on the coast of what’s now Chile and Peru between 9 million BP-4 million BP. Although Eremotherium also lived near the coast, it probably did not swim in the ocean as regularly as this species.
I propose to any vertebrate paleontologists who read this blog, to check your Eremotherium specimens for sand abrasions. Maybe you can publish a paper about it and thank me for bird-dogging the idea.
Amsen, Eli; et. al.
“Gradual Adaptation of Bone Structure to Aquatic Lifestyle in Extinct Sloths from Peru”
Proceedings of the Royal Society of Science 281 (1782) 2014