A prehistoric leviathan that represented a more savage Moby Dick once hunted smaller whales around 12 million or 13 million years ago, researchers say.

Fossils of the whale's skull and foot-long teeth found in Peru suggest the monstrous sperm whales ranged in size from almost 43 feet (13 meters) to 59 feet (18 meters), or longer than a school bus. Just the skull alone reaches a length of almost 10 feet (3 meters).

The ancient sperm whale's killer arsenal included 14-inch- (36-cm)- long teeth resembling elephant tusks that allowed it to rip and tear its prey, unlike modern sperm whales that lack functional teeth in their upper jaws and rely upon suction to grab giant squid.