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WASHINGTON — Plant-eating dinosaurs of different species may have herded together, to escape meat-eaters nearby, according to an analysis of 163 million-year-old dino footprints on a muddy coastal plain in England. 

In a study appearing Friday in the journal Science, British researchers say that 40 tracks of dinosaur footprints hint at a life and death struggle between prey and hunter in the days when dinosaurs ruled the world. 

The tracks suggest that large and lumbering plant eaters of different types — some as long as 90 feet and weighing 10 tons or more — walked together across an open tidal plain, 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 Megalosaurus, 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 Megalosaurus 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.”