From Newsday

["Garrison Hilliard"<garrison@efn.org>]

http://www.newsday.com/news/politics/wire/sns-ap-dino-tracks0531may30.story


Dinosaur Footprints Offer Clues
By PAUL RECER
AP Science Writer

May 31, 2002, 2:47 AM EDT

WASHINGTON -- Researchers analyzing 163 million-year-old footprints found
hints of a life-and-death struggle between prey and hunter in the days
when dinosaurs ruled the world.
say that 40 tracks of footprints preserved in stone suggest that
plant-eating dinosaurs of different species may have herded together to
escape meat-eaters that lurked nearby.

The tracks suggest that large and lumbering plant eaters of different
types -- some as long as 90 feet and weighing 10 tons or more -- crossed
an open tidal plain together, perhaps fleeing for their lives. These
animals were all sauropods, but of different types.

On a nearby track, the researchers also found the footprints of the
smaller, faster meglosaurus, a toothy meat-eater that may have been more
than 60 feet long. The tracks were going the same direction at about the
same time as the sauropods. The meglosaurus was a theropod, the same
family as Tyrannosaurus rex, a heavyweight carnivore that developed
millions of years later.

"The theropods there suggests that they were tracking the sauropods," said
Julia Day, a paleontologist at the University of Cambridge, England, and
first author of the Science study.
Day said the tracks of the sauropods show they were miles from the nearest
heavy growth of plants, which was unusual because it is believed the huge
vegetarians required food almost constantly.

"Sauropods have to keep eating and yet they were far away from any
vegetation," said Day. "We believe the animals were either migrating or
walked out there to get away from the predators."

The sauropods moved slowly, spread out and walking in the same direction,
with each animal leaving a set of several footprints.

In one track, a juvenile's small, shorter footfalls appear beside the
prints of a much larger sauropod, Day said. This suggests a parent and
child traveling together across that ancient muddy plain.

Day said the herding of plant-eaters from different species is not
unusual. In modern Africa, zebra and wildebeest commonly move together
over the grasslands and across the rivers of Tanzania and Kenya.

"This is the first evidence of a multispecie herd of dinosaurs moving
together," she said. "If they were migrating, they may have been going to
a new food source and to a nesting ground."

The plain where the animals moved was covered with a clay soil that baked
hard in the sun and eventually turned to limestone, preserving the
footprints. Day said the prints had to be made at approximately the same
time because the area was daily covered with ocean tides.

The types and sizes of the animals could be identified by the shape, width
and depth of the footprints, she said.

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On the Net: Science: http://www.sciencemag.org




In a study appearing Friday in the journal Science, British researchers