In this undated photo released by the University of Utah, geologist Winston Seiler poses next a trackway, or set of prints made by the same dinosaur, as it walked through a wet, sandy oasis some 190 million years ago in what is now the Coyote Buttes North area straddling the Utah-Arizona border. Seiler and Marjorie Chan, chair of geology and geophysics at the University of Utah, published a new study in the October issue of the science journal Palaios showing that numerous impressions at the site are dinosaur tracks, not erosion-caused potholes as was believed previously.(AP Photo/University of Utah, Nicole Miller) Credit: Nicole Miller.