BEIJING -- A fossilized skeleton of a turtle, dating back about 228 million years to the dawn of the dinosaur era, has been found in China, shedding new light on the earliest evolution of turtles.

This is the oldest turtle ever discovered with a toothless beak. The turtle, more than 2 meters long, with a short trunk, had no shell on its back and abdomen, said Li Chun, a researcher at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences.

Found from the late Triassic deposits in Guanling county in Southwest China's Guizhou province, it has been named Eorhynchochelys, meaning "first turtle with a beak", and featured in the latest issue of the academic journal Nature.

"We are familiar with modern turtles, but the evolution of turtle remains one of the biggest mysteries in paleontology," said Li, the lead researcher.

The body of a turtle is quite different from all other tetrapods, such as lizards, crocodiles, birds and mammals. A turtle has a very short trunk, enclosed by its shell. Modern turtles have toothless beaks similar to those of birds, said Li.

The discrepancy between turtle and other tetrapods is as large as the difference between a cable car and other automobiles.

Eorhynchochelys, or the turtle with the earliest beak, showed primitive, derived and transitional features, indicating a complexity in the early stage of turtle's evolution, Li said.

"Its skeleton suggested the turtle might have lived an amphibious life near an estuary, and had a habit of digging holes," Li said.

Reviewers of Nature commented that the finding was extremely important as it closed a major gap in the evolution of turtle, and indicated the development was more complex than previously assumed.