National Geographic : 2010 May
FOSSILS PHOTO: JOHN WEINSTEIN SOURCE: RYOSUKE MOTANI, UNIVERSITY OF CALIFORNIA, DAVIS NG GRANTEE How the West Was Swum Nevada is covered in desert and ranks as the driest U.S. state. Yet 240 million years ago it was submerged under a vast ocean. A land animal turned marine reptile called the ichthyosaur---"fish lizard"---was so common there it's now the official state fossil. But serrated teeth nearly half a foot long on a specimen bigger than a killer whale? Unheard of---at least until recently. University of Chicago paleontologist Nadia Fröbisch, who excavated the fossil in 2008 from the Augusta Mountains, thinks this top predator used its teeth to rip through the flesh and bones of defenseless fellow ichthyosaurs, many of which were smaller, and some of which had no teeth at all. No one knows how long this particular species ruled these waters, though the entire order died out around 90 million years ago, after a 160-milllion-year run. As Fröbisch explains, "They were a very successful group." ---Hannah Bloch A jaw full of five-inch, knife-edged teeth let this newly unearthed ichthyosaur (above) tear into prey. The four-finned, 40-foot- long species swam in what's now Nevada.