The fossil record is chock-full of ground-dwelling sloths ranging from medium-sized to mammoth (literally). But these days, there are only a few small sloths, and they all live in trees. Researchers ...

Two groups of sloths are left on Earth now — two- and three-toed sloths — but there are more that have existed in the Americas throughout history. Some are small creatures that lived up in the trees, ...

Photo via Toucan Rescue Ranch. Did you know that sloths used to be one of the most biodiverse groups of mammals to ever live in South America before the formation of the isthmus? Yeah, maybe it’s not ...

Ancient sloths ranged in size from tiny climbers to ground-dwelling giants. Now, researchers report this body size diversity was largely shaped by sloths’ habitats, and that these animals’ precipitous ...

New studies by two research teams published today in the journals Nature Ecology and Evolution and Current Biology challenge decades of accepted scientific opinion concerning the evolutionary ...

The aquatic sloth Thalassocnus is represented by five species that lived along the coast of Peru from the late Miocene through the late Pliocene. A detailed comparison of the cranial and mandibular ...

Long before today's tree-dwelling sloths became icons of leisure, their ancestors roamed the ground as colossal herbivores.

Pleistocene ground sloths constitute a remarkable and diverse group of xenarthran mammals that thrived across South America during a period of significant climatic and environmental flux. Their fossil ...

An ancient sloth weighing some 5 tons and sporting claws that extended a foot (0.3 meters) is helping to reveal how the slow, furry creatures ballooned in size long ago at a startlingly fast rate, a ...

The sloths we know and love today may be small and slow, but they're survivors. Unfortunately, the bulk of sloth species that once roamed the earth -- some of which grew to be the size of elephants -- ...

If patience were a superpower, sloths would wear the crown. These famously slow-moving creatures spend their days dangling ...