A team of scientists identified an ancient shell-less lizard that lived in the Triassic Period as the "grandfather" of modern turtles.
According to Reuters, authors of a study published in the journal Nature determined the lizard, named Pappochelys rosinae, lived some 240 million years ago. It grew up to eight inches in length and had an oddly shaped body that now appears to be a predecessor to shells.
For this reason, the scientists chose the name Pappochelys, which means "grandfather turtle."
"We now have well over a dozen specimens, including partial skeletons but also some isolated parts of skeletons," study co-author Hans Sues, a curator of vertebrate paleontology at the Smithsonian Museum of Natural History in Washington, D.C., told Live Science. "But we have a nice spectrum of sizes, so you can sort of see how the animal grows and changes."
The oldest known turtle is an animal called Odontochelys that lived about 20 million years after Pappochelys. Odontochelys had a more developed shell, which had a certain resemblance to Pappochelys'.
"The belly armor is composed of thick, rib-like bones that are beginning to fuse to each other in many places," Sues told Reuters. "[The discovery is] an important stage in the evolution of the turtle shell."
Modern turtles' ribs and spines are infused with their shells, but previous studies had suggested the possibility of their ancestors roaming the Earth without that signature characteristic. The new study confirms that of turtles' ancient lineage.
"Transitional creatures are the most important contribution that paleontology can make to the study of evolution. They are often unexpected and show surprising features," study co-author Rainer Schoch, of Germany's State Museum of Natural History Stuttgart, told Reuters. "They show how complicated structures like the skull or turtle shell formed step by step, and also give evidence on the sequence of evolutionary steps."
