United States:If you were unfortunate enough to share the planet with tyrannosaurus rex, there were two ways not to be eaten - either outrun the predator or hide from it. An exquisitely preserved fossil of one of T rex's plant-eating contemporaries shows that it did both.
Dakota, as the find has been nicknamed, was 16km (10 miles) an hour faster than its enemy and had a stripey pattern on its skin, possibly to break up its outline and make it less visible.
The scientists who have analysed the specimen say its body was subjected to a natural but extremely unusual mummification process after it died, preserving not just bones but skin and soft tissues.
"When you get up close and look at the skin envelope it's beautiful. This is not a skin impression, it's fossilised skin. That's very, very different," said Dr Phil Manning, the palaeontologist at Manchester University who has led the investigation. The exquisite detail allows researchers to find out how the animal moved - and preliminary investigations have suggested the way museums put dinosaur fossils together for display is incorrect.
The "dinosaur mummy" is a 3,600kg hadrosaur, or duck- billed dinosaur, which died 65 to 67 million years ago - shortly before other dinosaurs became extinct, probably because of a massive meteorite impact.
What makes this fossil unique though was what happened next. Skin and soft tissues are not usually present in fossils because they rot down quickly before fossilisation takes place. In this case, though, something unusual about the mud meant that didn't happen.
Dakota was named after the American state in which it was found in 1999 by a 16-year-old fossil hunter called Tyler Lyson.
The animal - which lived on a coastal flood plain and is probably an edmontosaurus annectens - has already thrown up surprises. One is that the animal's rump was 25 per cent larger than palaeontologists had previously assumed. That means more muscle power and greater acceleration.
In a paper reported in August, Dr Manning and colleague Dr Bill Sellers used a computer model to work out how fast dinosaurs, including T rex, could run. Dakota's fossilised rump gave them more information and they estimated it could have done 45km/h (28mph).
The specimen has also allowed the fossil hunters to see how the animal's vertebrae were connected in life. They have found each was separated by a centimetre of soft tissue.
That means museum curators are underestimating the size of dinosaurs by erecting fossils with no gaps. A specimen with 200 vertebrae, for example, would be two metres longer with the extra gaps.
- (Guardian service)