Fossils of the oldest known turtles, unearthed in southwestern China, may help answer an evolutionary enigma—how did the turtle get its shell?
The 220-million-year-old animals did not have full shells, or carapaces, on their backs, researchers found.
The 220-million-year-old animals did not have full shells, or carapaces, on their backs, researchers found.
But the newfound creatures did sport fully developed plastrons—the flat part of a turtle shell that covers and protects the belly.
The discovery supports the theory that turtle shells formed from the underside—plastron first—and grew bony extensions of ribs and bone formation above backbones that eventually joined to form the classic shell that exists today.
The discovery supports the theory that turtle shells formed from the underside—plastron first—and grew bony extensions of ribs and bone formation above backbones that eventually joined to form the classic shell that exists today.
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