But one thing's for certain: the discovery of more than 3,000 dinosaur footprints all facing the same way proves they were determined to get out of China's eastern Shandong province.
All this happened 100 million years ago and involved six different dinosaur types, including the well-documented Tyrannosaurus, experts told the Xinhua state news agency.
After a three-month excavation the footprints, called rare in terms of their number and total size, were uncovered in an area of more than half an acre on a rock slope in a gully in the city of Zhucheng.
Dinosaur fossils have been uncovered at about 30 sites in Zhucheng, which is now known as a "dinosaur city." In 2008, the biggest dinosaur fossil field in the world, containing more than 7,600 fossils, was unearthed, an expert told the news agency.
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Zhucheng, China has been dubbed "dinosaur city" for the troves of fossils found in the area. Here, a Chinese worker walks last year on a hill in Zhucheng strewn with thousands of dinosaur bones.
Why were the footprints, which ranged from four to 31 inches in length, all in one direction?
According to one expert, Wang Haijun, it might have been the result of migration. Or it could have been because of panic by plant-eating dinosaurs confronted in a surprise raid by meat-eating counterparts, he said.
More digging will go on at the site, and more prints could be discovered, Wang said.
Dinosaurs disappeared from the Earth about 65 Million years ago. The most popular theory is that they were wiped out by an asteroid impact, perhaps in the Gulf of Mexico, that cut off the essential benefits of sunlight.
But several lesser-known theories that are being supported by experts are also being examined, according to the Miami Science Museum, which presented an exhibition of Chinese dinosaur finds in 2007.
