Footprints unearthed in an ancient flood plain in northwest New Mexico may be the oldest dinosaur tracks yet discovered in North America, researchers from the University of Colorado and the U.S. Geological Survey say.
The four prints appear to have been made by a turkey-size ornithiscian, a plant-eating dinosaur that lived some 225 million years ago, said Stephen Hasiotis, a doctoral student in geology at the University of Colorado in Boulder who also works for the geological survey.Fossil footprints provide researchers with important clues to the behavior of the dinosaurs that made them, Hasiotis said, adding that "each individual makes hundreds of thousands of tracks in its lifetime, so the preservation potential for tracks is much greater than for body fossils."
The first of the four footprints was discovered near Fort Wingate about 11 years ago by Dr. Russell Dubiel, a researcher with the geological survey. Subsequent field work by Hasiotis, Dubiel, Dr. Martin Lockley, a dinosaur track expert at the University of Colorado in Denver, and Kelly Conrad of the geological survey led to the discovery of three more tracks.
The footprints were dated by determining the age of the rock layer in which they were found. The researchers reported their findings recently at a meeting of the Geological Society of America in Durango, Colo.
The oldest previously known dinosaur footprints in North America were left by a meat-eating species that inhabited what is now North Carolina some 200 million years ago, Hasiotis said.
The New Mexico tracks are similar to ones found in France that are believed to be about 240 million years old, Hasiotis said. Since the oldest known dinosaur remains are believed to be about 228 million years old, he said, the French footprints suggest that dinosaurs may have evolved earlier than previously suspected.