Shell Game; February 2009; Scientific American Magazine; by Kate Wong; 1 Page(s)

Vertebrate animals come in all shapes and sizes. But some have evolved truly bizarre forms. With beaks instead of teeth and shells formed by the ribs and other bits, turtles surely rank among the strangest of our backboned brethren. Indeed, paleontologists have long puzzled over how turtles acquired their odd traits and who their closest relatives are.

Previously, much of what researchers knew about turtle origins derived from fossils of Proganochelys from Germany. Based on that creature, with its heavily built shell and spiked plates covering the neck and tail, researchers had proposed that turtles were kissing cousins of a group of extinct armored reptiles known as pareiasaurs.