15 The Evolutionary Shell
Turtles are a novelty, no other animals share their incredibly hard external shell. Although an ancestor, the 260-million year old fossil, Eunotosaurus (on the right) has sparked new research. We see its structure, with ribs, shoulder bones and vertebrae from which the turtle evolved.
Turtles today are made up of around 50 bones that fuse together creating it’s unique shell. Eunotosaurus share in the same T-shaped ribs but not the broad spine on its vertebrae or the fully flattened and fused ribcage. They also lacked the muscles that now grow between the ribs in turtles.
The ancient fossil almost looks recognizable, as if it’s from the same family. By comparing the species of two eras, the Eunotosaurus has help scientist demystifies the turtle’s evolutionary process.
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