How did the turtle get its shell?

The origin of turtles has long put paleontologists in a quandary. How did an animal so unique in its physical appearance manage to acquire a shell that it can hide in?

Pappochelys is part of the answer. Meaning “grandfather turtle,” Pappochelys is an 8-inch-long reptile from the Triassic Period of Germany, dating back some 240 million years ago. It didn’t look much like modern turtles. It lacked a shell, but it had features that were precursors to the body parts of turtles. It had the makings of what would become the carapace, or the upper part of the shell -- thick, sturdy ribs. And also the beginning of what would become what’s called the plastron -- an array of hard bones along its belly.

Although to the untrained eye, the fossils do not resemble turtles, the body form and the time period from which Pappochelys came make it the best candidate for being an early turtle ancestor.