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 ...

Sloths like these once lived from Alaska to Argentina, and some species had bony structures on their backs, called osteoderms ...

Sloths like these once lived from Alaska to Argentina, and some species had bony structures on their backs, called osteoderms — a bit like the plates of modern armadillos — that may have been ...

Sloths like these once lived from Alaska to Argentina, and some species had bony structures on their backs, called osteoderms - a bit like the plates of modern armadillos - that may have been used ...

In another terrarium, Sash, a two-toed sloth, demonstrates a placid agility, grasping a wooden beam while reaching down to nibble greens from a plate. Maybe Sash should just go and get the plate.

Sloths like these once lived from Alaska to Argentina, and some species had bony structures on their backs called osteoderms — a bit like the plates of modern armadillos — that may have been ...