Forming Fossils

First Fossils

What can some trace fossils of dinosaur tracks tell us?

Numerous fossilized dinosaur footprints, called a trackway, indicate much about dinosaurs’ speeds. One such trackway is located north of Flagstaff, Arizona, on the Navajo Reservation. This site was first discovered by Barnum Brown of the American Museum of Natural History in the 1930s, but had been lost until recently. It includes an example of a running dinosaur that left tracks with an 8-foot (2.4-meter) space between the right and left prints; from these prints, scientists calculated that the dinosaur ran at speeds of 14.5 miles (23.3 kilometers) per hour—one of the faster dinosaurs known. The record for fastest dinosaur, however, is presently held by a Jurassic carnivore that left a 16-foot (5-meter) gap between the right and left tracks in a Glen Rose, Texas, trackway. The calculated speed of this dinosaur was about 26.5 miles (42.8 kilometers) per hour, much faster than the speediest human.


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