Thursday, 18 February 2010

Deadliest sin

I like sloths as they make me feel something approaching energetic. Anything that moves so slowly it gets covered in moss deserves some respect, I reckon. In Tucson there was a brilliant giant sloth skeleton. Xenarthrans are a strange group of animals that have weird extra joints between their vertebrae. Living examples include armadillos and anteaters as well as the more familiar, tree-dwelling sloths.

There were a number of distinct groups of 'ground sloths', living a variety of lifestyles. Some would climb trees to feed and it is thought a few may even have tried their hand at a doggy paddle to add a little seaweed to their diets. The more impressive of them, though, were the giant varieties, which were very much earthbound. Appearing in the fossil record in Southern Argentina early in the Oligocene, between 35-36 million years ago, they developed and spread throughout the then-isolated continent of South America. By island hopping and with some temporary land bridges, they gradually spread North. By the late Pliocene some had made it to North America. Some even made it as far as Alaska. A few smaller species preferred the warmth of the Caribbean islands and it's thought the last surviving examples died out in the Antilles, perhaps only about 4,000 years ago. Remains mummified by extremely dry conditions in South American caves have been found, providing information on soft tissue and hair. And also leading to more than one expedition to find a living beast.

The biggest ground sloths, like Megatherium and Eremotherium, were gimungous, weighing in at over 3 tons and 20 feet tall when rearing up on their hind legs. They may have been slow but you wouldn't want one waving its mighty, claw-packed paw at your face.


Dr. Bill, "Memory Medic" said...

Armadillos are really fascinating creatures. For more about this living fossil, see the book by Dr. W. R. Klemm, 'Dillos. Roadkill on Extinction Highway? Information is at

Matt Dale said...

Thanks Dr Bill. Will get round a post on glyptodonts, etc at some point. Armadillos are one of my favourite animals, so I'll check it out.