One of the largest living land mammals, rhinoceroses once shared the earth with saber-toothed cats and the earliest humanlike apes.

Combine a bulbous snout with a prominent jaw, a body like a beer keg set on four stubby legs, and you have a hippopotamus.

Sensitive, intelligent elephants are the world’s largest land mammal (by weight) and a living link to long-extinct species like the woolly mammoth.

American alligators are large aquatic reptiles with strong jaws, armor-like bodies and muscular tails.