The plant-eating Psittacosaurus had a thick layer of shark-like skin hidden under scales or feathers.
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.
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.
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.
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.
And here I thought that dino mummies were rare. Silly me. ;)
Is this our first ceratopsian mummy?