The word “Pleistocene” always reminds me of that malleable sculpture substance that is really good at getting stuck under fingernails. That stuff, however, is plasticine and is not the topic of the 5-part series of posts that is coming your way.
Pleistocene refers to the geological epoch from about 2.5 million years ago (mya) to about 10 000 years ago (10 kya) and it contained ice ages (glacial periods) and warmer periods where the glaciers retreated (interglacial periods). In our neck of the woods (the Americas), the isthmus of Panama had just erupted out of a volcano and the hitherto separated North and South Americas were now linked. Curious creatures of all shapes and sizes traded Americas about 3 million years ago and some thrived in their new homes while others could not compete. One of the animals that decided to stay in South America is of particular interest to me because I had never heard of it before and it is AWESOME. Readers, may I present Megatherium Americanum: the giant american ground-sloth.
Weighing in at a hearty 4 tonnes and measuring approximately 6m (20ft) from head to tail, this terrifying tower of four-toed fury was the king of the South American plains. It had a long claws on the end of fore- and hind-limbs, a heavy tail, and probably a very long, rough tongue. Skeletal studies reveal that it walked on all fours, but could easily stand up, with its hind legs and tail forming a tripod. That would have been an impressive sight. Originally thought of as an herbivore, recent research on this monster’s teeth and jaws suggests that Megatherium Americanum was an omnivore and dined frequently on meat. Its main source of food being vegetation, it used its claws and incredible height to strip leaves and fruit from the tops of trees.
Unlike its extant (still living) cousin the tree-sloth, this bad boy was no slouch. It could run, stab, and steal the kills of Pleistocene carnivores. In a 1996 biomechanical study, researchers from Uruguay reported that the muscles of M. Americanum‘s forelimbs were optimized for speed rather than power (an adaptation usually found in carnivores) and that the power behind the claws of Megatherium could easily pierce flesh.
Here’s a video of a possible Pleistocene scenario. I promise, it’s worth the watch. One-hit KO. (Edit: Video has since been taken down… Sorry)
In case you’re wondering, those cute furry cats are called Smilodons. They will be featured in a future post.
Sources:
https://en.wikipedia.org/wiki/Megatherium
https://en.wikipedia.org/wiki/Great_American_Interchange
http://en.wikipedia.org/wiki/Pleistocene
Bargo, M. S. (2001). The ground sloth Megatherium americanum : Skull shape , bite forces , and diet. Acta Palaeontologica Polonica, 173–192.
Farina, R. A., & Blanco, R. E. (1996). Megatherium, the Stabber. Proceedings: Biological Sciences, 263(1377), 1725–1729.
Jon Farrow 
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