Dinosaurs could run at 20 mph, tracks indicate Site re-discovered after 60 years

May 21, 1993|By San Francisco Chronicle

RENO, Nev. -- Rare tracks of carnivorous dinosaurs running at nearly 20 miles per hour, each stride covering 16 feet, have been found in a remote part of the Navajo Indian Reservation, a paleontology team reported.

The measurements come from a site marked by footprints of many dinosaurs. The tracks are in rock that was a muddy shore in the early Jurassic epoch about 180 million years ago. Scientists first briefly noted them in the 1930s, but the location was lost again until a recent search -- using a single photo as a clue -- turned it up.

Only four or five other track sites are known worldwide on which the dinosaurs were moving at more than a walk. "We have at least three different creatures running, and perhaps as many as six," said Grace V. Irby, a paleontologist at the Museum of Northern Arizona in Flagstaff.

Ms. Irby says the site looks like a "dinosaur dance floor" more than 50 feet across. It is crisscrossed by at least 34 dinosaur trails. Each is marked by the distinctive three-toed prints of meat-eating dinosaurs.

The exact types of species in the tracks are not known, but Ms. Irby suspects that at least some of them were from a dilophosaurus, a fierce-looking creature about 18 feet long. The running prints came from smaller meat-eaters, "about my size, and I'm 5-foot-3," she said.

The rapid pace of the dinosaurs adds to suspicions, she said, that dinosaurs may have been warm-blooded and capable of extreme exertion, like modern birds, rather than cold-blooded like reptiles such as alligators or lizards.

But Ms. Irby and other scientists say the ability of dinosaurs to run is not by itself enough to prove the case. "Even crocodiles can move pretty fast for a short distance," said Michael Morales, a paleontologist at the museum and co-author of the report presented yesterday.

The location of the tracks is about 20 miles from Cameron, a small trading post near the western edge of the sprawling Navajo lands.

In the 1930s, famed dinosaur hunters Barnum Brown and Roland T. Bird of the American Museum of Natural History first heard of the site. An old Navajo man described giant bird tracks in the desert. Mr. Bird published a photo of himself at the spot but he made no map.

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