THE footprints on rock read like a diagram for the T-Rex tango. Geologists have identified a small site on the Arizona-Utah border that is so packed with prehistoric animal tracks it has been dubbed "a dinosaur dance floor".
While the ferocious lizards of 190 million years ago were not known to favour social choreographed movements, unless dining upon each other, researchers believe the three-quarter acre site in the Vermilion Cliffs National Monument area was a place, p
erhaps a watering hole, where the creatures were "happy".
During the Jurassic period, large stretches of the American west were a desert, so the presence of more than 1,000 tracks of a variety of creatures has led geologists to conclude the site was an oasis.
The footprints are now providing rich fodder for researchers trying to understand dinosaurs that survived in what many considered a vast, uninhabitable desert.
"Get out there and try stepping in their footsteps, and you feel like you are playing the game 'Dance Dance Revolution' that teenagers dance on," says Professor Marjorie Chan from the University of Utah. "This kind of reminded me of that – a dinosaur dance floor – because there are so many tracks and a variety of different tracks."
The discovery adds yet another site to the region's long list of dinosaur hotspots. The difference is sheer number of prints. In some places, there are a dozen footprints in a square yard. Researchers identified four different kinds of tracks in the rock but have not determined which species left them behind.
Some of the footprints – once thought to be potholes formed by erosion – measure 16 inches across and have three toes and a heel. Others are smaller and more circular. The area also includes what researchers think are rare marks left by a tail.
Winston Seiler, who studied the site, said the area might have been a popular gathering spot. It could have been one of many where Early Jurassic dinosaurs stopped for refreshment before moving on.
Mr Seiler imagines dinosaurs were "happy to be at this place, having wandered up and down many a sand dune, exhausted from the heat and the blowing sand, relieved and happy to come to a place where there was water".
The study's findings were published in this month's issue of the journal Palaios. "It's an exciting site and deserving of a lot more work," said Jim Kirkland, Utah's state paleontologist.
He hopes that paleontologists will begin a large-scale survey of the site.
Dinosaur tracks can provide important insight on behaviour and movements across the landscape, said Andrew Milner, paleontologist at the St George Dinosaur Discovery Site at Johnson Farm in south-western Utah.
The newly discovered site, about three miles from the nearest road, is part of a protected wilderness area that also includes a sandstone geologic formation called The Wave.
Twenty permits are issued each day to enter the area. Linda Price, the monument's manager, expects interest in the spot will soar with word of the dinosaur tracks site. Scientists say the prints were preserved in sandstone after being covered by shifting dunes.
They became exposed through erosion and will eventually disappear through erosion, too.
