The First Sea Monster

Giant ichthyosaur gobbled its companions with killer teeth.

By Fredric Heeren

Researchers have announced the discovery of the first sea monster (artist’s impression above)—an 8.6-meter-long reptile with a massive skull (inset) and sharp teeth that lived 244 million years ago. The creature, described online today in the Proceedings of the National Academy of Sciences, was an early ichthyosaur, a four-footed reptile turned seafarer. Unlike other ichthyosaurs, however, whose diets consisted mostly of fish and clams, this one would have fed on larger prey, including other ichthyosaurs. Found in 244 million-year-old Triassic rocks, Thalattoarchon saurophagis lived just 4 million years after the first appearance of marine reptiles in the fossil record and lived just 8 million years after the great Permian-Triassic extinction, which wiped out 90% of ocean life. This placement demonstrates both the mercurial evolution of the macropredator and the rapid rise of modern marine ecosystems, the researchers note. The creature also illustrates convergent evolution, showing that some land-dwelling reptiles evolved into sleek-looking sea creatures in much the same way that some mammals evolved into whales and dolphins. The remains of the creature were discovered in 1998 in the remote mountains of central Nevada. A few years later, others reviewing the scientists’ field notes learned of the unusual ichthyosaur teeth with two cutting edges. Researchers returned to the site to relocate the fossil and eventually secured a grant from the National Geographic Society to fund an excavation in 2008, revealing the massive skull.