Covering near-vertical rock faces in a Spanish quarry, these trackways of oversized footprints have been preserved since the Cretaceous Period (more than 65 million years ago).
Though the prints, which range in length from less than an inch to more than three feet, now span steep surfaces, the scientists say the land was flat when the dinosaurs lived. “Many of the tracks can be clearly defined as depressions on the now-tilted surface—a result of uplift during mountain building events—on which the animal once walked,” said lead scientist Phil Manning, a paleontologist at the University of Manchester in England.
The work will help scientists understand dinosaur locomotion.
“We are very interested in studying tracks of dinosaurs that walked on two legs, given there is no modern analog that would help us understand the locomotion of such animals,” Manning told LiveScience.
Paleontologists spotted the giant footprints in the early to mid-1980s at the Fumanya site, in central Catalonia (in the eastern Pyrenees). Because the sediment is so delicate, however, they couldn’t get close enough to examine the impressions.
"Due to the fragile environment and the sensitivity of the site, we were not permitted direct contact, and therefore all measurements had to be taken remotely,” said post-graduate student Karl Bates of the University of Manchester, who did some of the study’s field work.
Wind and rain have eroded away some of the markings, so time was of the essence if scientists wanted to get a close look at the ancient steps.
To preserve the tracks, Manning and his colleagues used a laser scanning system called RIEGL, which used laser beams to scan the footprint-adorned quarry face. The beams reflect off the surfaces and carry detailed information back to a receiver. The scanning device combines the beam information with images from a built-in digital camera and GPS for precise locations.
By feeding the data set into a software program, the scientists created a 3-D model of the area.
"The computer-generated trackways we have created preserve important information on the locomotion of dinosaurs, which can be properly accessed for the first time,” Manning said.
The results will help scientists “see” dinosaurs as they walked, ran or maybe hopped over the land, answering questions such as: Did T. rex have a wide or narrow gait? Did theropods walk alone or in pairs?
“The relative position of each track helps constrain how the animal that left the track walked,” Manning said. The team will make simple measurements between quadrupeds' fore and hind tracks, for instance, as well as calculate the distance between shoulders and hips to refine locomotion models.
The scientists have also used the scanner to examine another site located mostly in Montana and known as the Hell Creek Formation, famous for its T. rex fossils.