What would you get if you crossed a whale with a shark? Maybe something like Leviathan melvillei, a long-extinct, hypercarnivorous whale with teeth longer than any T. rex ever had.

L. melvillei — a newly described sperm whale named to honor Herman Melville, author of the whaling novel Moby-Dick — lived between 12 million and 13 million years ago, says Olivier Lambert, a vertebrate paleontologist at the National Museum of Natural History in Paris. The aptly named leviathan is known only from remains of a jawbone and skull, which is about 75 percent complete, Lambert and his colleagues note in the July 1 Nature.

By comparing those fossils, which were found in southern Peru in November 2008, with more complete remains of other species, the researchers estimate that Leviathan measured between 44 and 57 feet in length, slightly smaller than adult male sperm whales of today.

The longest of Leviathan’s teeth measure about 14 inches including the root, more than 40 percent longer than those of today’s sperm whales. And, Lambert notes, the longest tooth of Sue, one of the largest Tyrannosaurus rex specimens yet found, measures only 10.6 inches from root to tip.

Wear patterns indicate that Leviathan’s teeth sheared past each other during a bite, a sign that the beast could rip chunks of flesh from prey. Lambert and his colleagues speculate that Leviathan fed on medium-sized baleen whales, whose blubber would have been a rich source of calories.

“This is a pretty exciting discovery,” says Erich Fitzgerald, a vertebrate paleontologist at Museum Victoria in Melbourne, Australia. Leviathan represents “one thing we don’t have in the oceans today — a macropredator, a hypercarnivorous whale.”

Modern sperm whales feed largely on invertebrates such as giant squid, but have been known to feed on fish and other creatures as well. The extremely robust, deeply-rooted structure of Leviathan’s teeth strongly suggests that the creature fed on large, presumably struggling bony prey like sharks do.

But that doesn’t mean the whale’s diet was restricted in any way. “If you’re big enough,” Fitzgerald notes, “you can bloody well eat what you want.”

Images: 1) Artist's rendering of the giant raptorial sperm whale Leviathan melvillei attacking a medium-size baleen whale off the coast of the area now occupied by Peru./C. Letenneur (MNHN).

2) Three lower teeth (a,b,c) of L. melvillei compared to teeth of the modern sperm whale Physeter macrocephalus (d) and the modern killer whale Orcinus orca (e)./G. Bianucci (Universitá di Pisa), O. Lambert (MNHN) and P. Loubry (MNHN).

3) Schematic drawings of the skull and mandible of L. melvillei in dorsal (a,d), ventral (b) and lateral (c) view./G. Bianucci (Universitá di Pisa)

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