Huge Field of Dinosaur Tracks Found More than 1,000 dinosaur footprints along with tail-drag marks have been discovered along the Arizona-Utah border. The incredibly rare concentration of beastly tracks likely belonged to at least four different species of dinosaurs, ranging from youngsters to adults. The tracks range in length from 1 to 20 inches (2.5 to 51 centimeters). "The different size tracks may tell us that we are seeing mothers walking around with babies," said researcher Winston Seiler, a geologist at the University of Utah. The tracks were laid about 190 million years ago in what is now the Vermilion Cliffs National Monument. "There must have been more than one kind of dinosaur there," said researcher Marjorie Chan, professor and chair of geology and geophysics at the University of Utah. "It was a place that attracted a crowd, kind of like a dance floor." While the site is covered in sand dunes now, the researchers say the tracks are within what was a network of wet, low watering holes between the dunes. In fact, the tracks provide more evidence of wet intervals during the Early Jurassic Period, when the U.S. Southwest was covered with a field of sand dunes larger than the Sahara Desert....