My favorite deadly sin... Sloth
Somehow I just do not automatically associate ground sloth fossils and South Dakota! Bison – yes; ground sloths – no. My colleague and co-PI, Sharon Holte, on our New Project Cave venture presented here have worked on some ground sloths over the years. Most of my work has been with the Shasta ground sloth, Nothrotheriops shastensis, dung from dried caves in AZ, UT, NV – and a new locality I am working on with archaeologists in west Texas. Sharon on the other hand did her MS thesis on the multitude of Megalonyx skeletons from a cave in Alabama. The Shasta ground sloth is known to have denned in caves – Rampart and Muav caves in the Grand Canyon, a cave near Las Vegas, Nevada, caves in the Guadalupe Mountains and others in western Texas and eastern New Mexico, Kartchner Caverns in southeastern Arizona, to name a few. This is a small ground sloth and apparently just did not disperse much further north than central UT or the Sierras of the California elbow at Nevada. Much larger is Megalonyx and it too apparently used some caves – at least those with a large enough entrance. I have always wondered if some sort of ground sloth (either Megalonyx or the large, Paramylodon) ever meandered into the northern high plains, eastern Wyoming, or the Black Hills. I did not recover sloth of any type in Salamander Cave (dating about 252,000 years old) and it is not found in The Mammoth Site here in the southern Black Hills, so I just assume it was not in this region during the Late Pleistocene.
Its record in this region of WY and the rest of the northern high plains is definitely poor to non-existent. A couple of months ago a rancher and a colleague unearthed a complete ground sloth lower arm, radius, found in association with Mammuthus and possibly Bison. I have not seen the Bison (which would indicate a Rancholabrean age, less than about 160,000 years old) but the mammoth and sloth are good identifications. So, now we need to pursue this new critter to the region. Now if we can just find it preserved in our New Project Cave. I would not expect to find the entire skeleton, but any number of its toes, carpals, or tarsals could easily get washed into our cave. --Dr. Jim I. Mead
2 comments