Researchers have finally cracked a paleontological puzzle that's puzzled scientists for decades. Miracinonyx trumani, long nicknamed the "American cheetah" for its sleek build and long front legs, wasn't a cheetah at all—it was actually more closely related to modern pumas.

The discovery, published in Current Biology, rewrites what we thought we knew about this extinct North American predator. Even more surprising: some populations living near the Arctic hunted almost exclusively on fish, completely upending the assumption that these cats were speedy chasers of pronghorns and other fast prey. This finding shows how much evolution can surprise us and how readily assumptions about the past can mislead us. Read the full story →

Today's takeaway: Ancient animals are full of surprises—this one reminds us that appearances can be deceptive, even across millennia.