A Peruvian desert has turned out to be the final resting place of an ancient sperm whale with teeth much bigger than those of the largest of today's sperm whales. The fossil, dated at 12–13 million years old, belongs to a new, but extinct, genus and species described in Nature today1. Named Leviathan melvillei, it probably hunted baleen whales. A team of researchers recovered 75% of the animal's skull, complete with large fragments of both jaws and several teeth. On the basis of its skull
Modern sperm whales lack functional teeth in their upper jaw and feed by suction, diving deep to hunt squid. Conversely, Leviathan had massive teeth in both its upper and lower jaws, and a skull that supported large jaw muscles. It may have hunted like raptorial killer whales, which use their teeth to tear off flesh. Co-author Klaas Post of the
The name given to the creature combines the Hebrew word 'Livyatan', which refers to large mythological sea monsters, with the name of
The authors think that Leviathan, like the extinct giant shark, preyed on medium-sized baleen whales, which were between 7 and 10 metres long, smaller than today's humpback whales and widely diverse at the time. The authors speculate that Leviathan became extinct as a result of changing environmental conditions. "Top predators are very sensitive to the changes in their prey," Lambert says. Changes in number, diversity or size of baleen whales, as well as the climate cooling that occurred at around Leviathan 's time, would have had dire impacts. The creature's surviving cousins — Physeter, pygmy and dwarf sperm whales — are specialized deep-diving squid hunters that occupy a different ecological niche from Leviathan. According to vertebrate palaeontologist Lawrence Barnes at the Natural History Museum of Los Angeles County, this discovery demonstrates that sperm whale-like cetaceans were much more diverse in the past and that the modern sperm whale and pygmy sperm whales are the "only surviving vestiges of a larger evolutionary radiation of related whales in the past".
The organ could have served other functions, such as echolocation, acoustic displays or aggressive head-butting. "Spermaceti organs could be used as battering rams to injure opponents during contests over