A newly identified fossil could explain one of evolution's biggest mysteries – the origin of the turtle's shell. Bone fragments from a 210-million year-old, land-dwelling reptile from New Mexico suggest that the earliest turtles didn't have much of a shell at all. Over millions of years, rows of protective armour plates gradually fused together and to the reptile's vertebrae, eventually creating a complete shell. "Turtles ultimately originated from something that looked like an armadillo," says lead author Walter Joyce.
Exactly why turtles evolved their shell remains a mystery, Joyce says. A full shell might offer added protection and stability. And the proof could be in the pudding – their body plan is the world's oldest, changing little over 200 million years. "For some reason just being a turtle is an idea that came along and just really works," he says.
Storyteller: Walter Joyce, a palaeontologist, Peabody Museum of Natural History, Connecticut
Source: Fossil reveals how the turtle got its shell
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