Quirks & Quarks

How The Turtle Got Its Shell

A new discovery of an animal with ribs starting to form a shell gives insight into the evolution of turtles.

A 240-million-year-old fossil was an early proto-turtle

Reconstruction of the proto-turtle (Rainer Schoch)
Fossils found in Germany have provided more clues as to how the turtle got its shell. The 240-million-year-old fossils are of a lizard on its way to becoming a turtle.

Dr. Hans Sues, the Curator of Vertebrate Paleontology at the Smithsonian's National Museum of Natural History in Washington, studied the fossils and described evidence of shell formation. The trunk ribs are expanded and have started to fuse together into one bone mass. This would eventually become the top shell. Similarly, the bones of a rib-like structure on the underside - or belly shell - are also starting to join together.

The fossils also support the idea that turtles are more closely related to lizards than to dinosaurs and birds. 

Related Links

Paper in Nature
- Smithsonian Magazine article
- Science news story
- Discover magazine story
LiveScience story