Fossil reveals a caring, sharing dinosaur

The monstrous image of the dinosaurs needs a more touchy-feely makeover after US researchers found convincing evidence that at least some of the king reptiles cared for their young and even dug burrows to hide from predators.

The find in Montana includes fossilised bones of an adult and two young. "Here we have the burrow, den, an adult with traits for digging, and two juveniles, all in the same place," said Anthony Martin at Emory University, Atlanta. "It doesn't get much better than that."

The juveniles are more than half grown, suggesting parents of the species cared for their young for a significant period.

Dr Martin and colleagues have named the species Oryctodromeus cubicularis, meaning "digging runner of the lair", due to its ability to both burrow and run on two legs. The beast, which is distantly related to the iguanodon, was just over 2 metres long (6½ft). The authors predict in the Proceedings of the Royal Society that it would have weighed 22-32kg (48-70lbs).

The team claim the burrow had been dug and was not somewhere the family had simply climbed into for shelter. The animal also had several features for burrowing, including a modified snout, possibly for use as a shovel. It also had a large attachment point on the shoulder joint for muscles, helping it dig with its front legs.

The ability to burrow would have given it many advantages, said Dr Martin, such as surviving harsh climatic conditions or catastrophes such as volcanic eruptions - rocks found in the sediment suggest there were active volcanos nearby. "Burrows have a nice way of evening out environmental conditions, like maintaining a stable temperature and humidity."

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