a fossilized giant ground sloth claw that had been buried in more than 11,000 years ago... The Megatherium, or giant ground sloth, stood 15 feet tall and weighed more than three tons.
An analysis of the sloth family tree suggests three different groups of the animals evolved to gigantic sizes in response to cold and dry conditions ... .
The excavation has already dug up a giant find — the tooth of a GiantGroundSloth... the Nothrotheriops shastensis, known as the Shasta Ground Sloth, and the Megalonyx, or Large Clawed Ground Sloth, according to the National Park Service.