By Helen Briggs
Science reporter, BBC News
A fossil unearthed in China has given scientists a rare glimpse of what dinosaurs were like in the flesh.
Some scientists believe a number of dinosaurs had feathers
The plant-eating Psittacosaurus had a thick layer of shark-like skin hidden under scales.
Palaeontologists believe this tough outer coating supported the dinosaur's organs and protected it from predators.
Tooth marks suggest the dinosaur was torn open by a scavenger, giving a unique insight into their biology, 100 million years after this one's death.
The research is published in the Royal Society's journal Proceedings B.
Soft tissues such as skin are rarely preserved in the fossil record, leading to heated debate over what dinosaurs looked like, and whether they were covered in primitive feathers or scales.
The Psittacosaurus, or parrot lizard, specimen gives the first detailed picture of what dinosaurs were like deep under the skin.
The bipedal herbivore, which grew to about the size of a gazelle, had tough, scaly skin with more than 25 layers of collagen - similar to that of today's sharks, reptiles and dolphins.
"As noted from the studies on modern-day animals, this fibre structure plays a critical part in the stresses and strains the skin may be subjected to and is ideally suited to providing support and protection," explained Professor Theagarten Lingham-Soliar of the University of KwaZulu-Natal, Durban, South Africa, in the paper.
"Psittacosaurus gives a remarkable, unprecedented understanding of the dinosaur skin."
The specimen comes from an area of China that has yielded a treasure trove of uniquely-preserved fossils.
"Discoveries like this from China are certainly churning out new surprises," commented Mark Witton of the School of Earth and Environmental Sciences at the University of Portsmouth, UK.
"To have the skin folded on the fossil so that you can see the cross section through it is remarkable."
He said the skin of the dinosaur would have been "incredibly tough" and probably served to protect the animal from attack by predators.
"We imagine this Psittacosaurus as a tubby little animal walking around on its back legs," he added.
"Psittacosaurus may have been a bit like a prehistoric pig, wandering around woodlands and forests and eating all manner of plants, scavenging the odd carcass and maybe eating the odd little animal here and there."
The Chinese specimen appears to have met its match during the life and death struggles of the Lower Cretaceous.
Tooth marks and fractures in the skin suggest it was attacked by another dinosaur, and then covered by sediment rapidly after its demise, allowing soft tissue to be preserved in remarkable detail.