A newly discovered fossil from China has shed light on how the turtle’s shell evolved.
The 220 million-year-old find, described in Nature journal, shows that the turtle’s breast plate developed earlier than the rest of its shell.
The breast plate of this fossil was an extension of its ribs, but only hardened skin covered its back.
Researchers say the breast plate may have protected it while swimming.
The turtle fossil, found near Guangling in south-west China, is thought to be the ancestor of all modern turtles, although it differs markedly; it has teeth rather than a bony plate, the shell only covers its underside and it has a long tail.
“Since the 1800s, there have been many hypotheses about the origin of the turtle shell,” explained Dr. Wu. “Now we have these fossils of the earliest known turtle. They support the theory that the shell would have formed from below as extensions of the backbone and ribs, rather than as bony plates from the skin as others have theorised,” Dr Wu explained.
