The fossil is of a 130-million-year-old Psittacosaurus, or parrot lizard, a beaked reptile about the size of a pig that could walk on either two or four legs.

The research also suggests that some dinosaurs had thick, scaly skin like that of modern-day reptiles, refuting the theory that dinos had primitive feathers.

The findings were reported by Theagarten Lingham-Soliar of South Africa's University of KwaZulu-Natal in the current issue of the Proceedings of the Royal Society B.

"To have soft tissue preserved is amazing in the fossil record, because clearly the soft tissue is about the first thing that will decay and disintegrate," Lingham-Soliar said.

"Until now we had seen only surface preservations, but this is the first time we see a deep cross-section of the skin cut away at right angles to the surface."