Turtle evolution: Fossil

This fossil specimen of Pappochelys confirms that the belly portion of the turtle shell, called the plastron, formed through the fusion of rib-like structures and parts of the shoulder girdle. In June 2015, an international team of researchers from the United States and Germany discovered this new extinct species of reptile and identified a key missing link in the evolutionary history of turtles. (Image credit: Rainer Schoch, Stuttgart Natural History Museum)