The Dinosaur Dance Floor

Unlike dinosaur fossils, dinosaur footprints can often be found hiding in plain sight. Take, for example, the weird, pothole-like impressions dotting a small slice of the Coyote Buttes North area at the Arizona/Utah border. It's possible that numerous geologists and hikers had spent years stepping gingerly around these strange holes without realizing what they really were--until University of Utah paleontologist Marjorie Chan visited the site in 2005, and realized she was looking at thousands of dinosaur footprints.

After intensive study, Chan and her research team have identified the prints of four different types of dinosaurs at what they've dubbed the "Dinosaur Dance Floor"--including impressions left by an as-yet-unidentified tyrannosaur and sauropod. Even more striking than the footprints are a series of 2.4-inch wide, 20-foot-long trackmarks that were clearly left by dinosaurs dragging their weary tails in the early Jurassic mud 190 million years ago. Further study of this "trample surface," as it's known, should yield more clues about which dinosaurs inhabited this area of North America (and, possibly, what they were doing when they made their mark).