Geologists stumble on 'dinosaur dance floor' in Jurassic oasis

Washington, Oct 20 (IANS) Geologists have identified an amazing concentration of dino footprints, in a wilderness on the Arizona-Utah border where a desert oasis once flourished 190 million years ago.

The three-quarter-acre site - which includes rare dinosaur tail-drag marks - provides more evidence there were wet intervals during the Early Jurassic Period, when the US Southwest was covered with a field of sand dunes larger than the Sahara 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,' said Marjorie Chan, professor and chair of geology and geophysics, University of Utah and co-author of the study.

'This kind of reminded me of that - a dinosaur dance floor - because there are so many tracks and a variety of different tracks. There must have been more than one kind of dinosaur there. 'It was a place that attracted a crowd, kind of like a dance floor,' she said.

Located within the Vermilion Cliffs National Monument, the 'trample surface' (or 'trampled surface') has more than 1,000 and perhaps thousands of dinosaur tracks, averaging a dozen per square yard in places.

The tracks once were thought to be potholes formed by erosion. The site is so dense with dinosaur tracks that it reminds geologists of a popular arcade game in which participants dance on illuminated, moving footprints, according to a Utah University press release.

University of Utah geologist Winston Seiler said the range of track shapes and sizes reveals at least four dinosaur species gathered at the watering hole, with the animals ranging from adults to youngsters.

'The different size tracks [one to 20 inches long] may tell us that we are seeing mothers walking around with babies,' he says.

As part of the study, Seiler marked off 10 random plots, each of 4 square meters, or roughly two by two yards. He counted 473 tracks within those plots - an average of 12 per square meter.

He conservatively estimated the 3,000-square-metre site has more than 1,000 tracks, but he and Chan believe there perhaps are thousands.

Numerous dinosaur track sites have been found in western US, including more than 60 in Navajo Sandstone, where actual dinosaur bones are rare.

The study was published in the October issue of international paleontology journal Palaios.