Unchanged for 200 million years because evolution couldn't improve the design, the saltwater crocodile is a 2,200-pound ambush predator with the strongest bite ever measured in the animal kingdom. Its death roll can dismember prey in seconds, and it can lurk motionless for hours before exploding from the water at terrifying speed. Dinosaurs went extinct; this thing didn't.

Weighing in at a staggering 14,000 pounds, the African elephant is the largest land animal on Earth and a living battering ram wrapped in two-inch-thick hide. Capable of flipping cars and toppling trees on a whim, its intelligence rivals that of primates—complete with mourning rituals and long-term memory. Cross one and it will remember your face forever.