A desert discovery
In November 2008, paleontologists discovered a fossilized skull in the Pisco-Ica Desert of southern Peru. The skull was 3 meters (10 feet) long and belonged to an extinct species of sperm whale that lived 9.9 to 8.9 million years ago. The researchers named it Livyatan melvillei, named after the biblical sea monster Leviathan and to Herman Melville, the author of Moby Dick.
The fossil, catalogued as MUSM 1676, is now housed in the Museum of Natural History in Lima, part of the National University of San Marcos. The skull has its weaponry. It holds the largest known biting teeth of any animal, measuring up to 36.2 centimeters (1.19 feet) long. Unlike modern sperm whales, which have teeth only on their lower jaw for grasping squid, Livyatan had massive, functional teeth in both its upper and lower jaws. These features, along with a robust jaw and large muscles for closing it, indicate Livyatan was an apex predator capable of hunting large prey.
Ruler of the Miocene seas
Based on the skull, scientists estimate Livyatan reached a total body length between 13.5 and 17.5 meters (44 to 57 feet), similar to a modern adult male sperm whale. It occupied a similar ecological niche to modern killer whales, but on a much larger scale. Its primary diet likely consisted of medium-sized baleen whales that were 7 to 10 meters long.
Livyatan was not alone at the top of the food chain. It shared the oceans with another giant predator, the megalodon shark (Otodus megalodon). Both creatures were apex predators and likely competed for the same food sources, primarily other marine mammals. The fossil record of the Pisco Formation, where the skull was found, shows a diversity of marine life, including baleen whales, dolphins, and seals—all potential prey for Livyatan. The evolution of gigantic raptorial sperm whales like Livyatan coincides with a period when baleen whales were diversifying and increasing in size.
The reign of these mega-predators ended as the Earth's climate cooled toward the end of the Miocene. This cooling trend altered marine ecosystems and led to a decline in the populations of the medium-sized whales that Livyatan and megalodon relied upon for food. Without their primary prey, these giant hunters eventually starved into extinction.