The sloth family tree once sported a dizzying array of branches, body sizes and lifestyles, from small and limber tree climbers to lumbering bear-sized landlubbers. Why sloth body size was once so ...

Ancient sloths lived in trees, on mountains, in deserts, in boreal forests and on open savannas. Some grew as large as elephants. Illustration by Diego Barletta The largest sloth of all time was the ...

Hanging out in a rain forest, rarely coming down from the verdant  canopy where they are safe from predators; moving slowly, ...