Shell game: How the turtle got its home

PARIS (AFP) – A stunningly intact 220-million-year-old fossil found in southwestern China appears to have settled a long-simmering debate over reptile evolution: how did turtles get their shell?
In a study to be published Thursday, scientists report on the discovery of a missing-link species -- Odontochelys semitestacea, for "toothed, half-shell turtle" -- whose outer shell emerged directly from the ribs and backbone and not from the skin, as some have argued.
The find also suggests that turtles originated in water rather than on land, and pushes back the group's first known appearance on Earth by some 10 million years.
Since the era of dinosaurs, which roamed the planet until 65 million years ago, turtles have looked pretty much the way they do today.
They sport an armour-like upper shell, known as a carapace, connected to a softer lower part, called a plastron.