Scientists have been trying for years to determine how turtles developed their protective shells. There has been newly found evidence that turtles lived at one point without any shell over their back. A new fossil discovered from Guizhou province of south-west China dates back to 228 million years. This ancient fossil looks very much like a turtle and has a beak in the front end. This fossil has been named Eorhynchochelys sinensis, which means "Dawn turtle with a beak from China".
There are two theories about the emerging of the turtle shell. One states it formed from bony and scale-like growths that developed on the skin of reptiles. The other theory points that shells came when the ribs of some reptiles grew broader than the others. According to scientist Tyler Lyson of Yale University, "The turtle shell is a complex structure whose initial transformations started over 260 million years ago in the Permian period. Like other complex structures, the shell evolved over millions of years and was gradually modified into its present-day shape." Olive Ridley Sea Turtles Nests in Mumbai: Know More About the Species and Other Turtle Nesting Spots in India.
The skeleton found in China has some teeth and suggests the missing link in turtle evolution. The fossil is 2.5 metres long, with a lengthy tail and broad and flat ribs along its back. It appears to have formed the disc-like structure which later evolved into a shell. Chun Li, a Chinese researcher, co-author of study has written, "the specimen is an important missing link in the early evolution of the turtle." He has been studying turtle fossils in China for years now. So the latest finding also points at evolution from similar reptile ancestors.