Fossil discovered by kid suggests turtle shells were for burrowing, not hiding

An 8-year-old boy dug up this fossilized turtle that scientists believe helps explain the turtle's earliest uses of its shell(Credit: Wits University)

Every young boy has spent at least one afternoon digging a hole in the ground looking for some kind of treasure. An eight-year-old from South Africa was doing just that when he unearthed a turtle fossil that could help scientists understand the original purpose and evolution of the turtle's shell.

A group of scientists from parts of the world including South Africa, Switzerland and the United States conducted a study on several early turtle fossils including a fossil discovered by an 8-year-old Kobus Snyman on his father's farm in the Western Cape of South Africa. The study that took place at the University of Witwatersrand, Johannesburg found that early turtles may have used their shells for burrowing instead of for protection from potential predators.

The 5.9 inch (15 cm) long turtle fossil discovered by Snyman contains a preserved skeleton with articulated hands and feet. The study published in the journal Current Biology also examined several turtle fossils found in the Karoo Basin of South Africa including a partially shelled proto-turtle that's 260 million years old.

The wide rib patterns in the fossilized turtles' shells are the main clue that points to the shell's main function. This rib pattern provided a weaker form of protection but more rigidity across the thorax, which indicates that the ribs — which form the turtle's shell — moved into place over time as the turtles used their shells to burrow into the Earth.

Dr. Tyler Lyson of the Denver Museum of Nature and Science who participated in the study says this broader rib pattern suggests that shells may not have served as the protective function that scientists originally believed.

"Why the turtle shell evolved is a very Dr. Seuss like question and the answer seems pretty obvious – it was for protection," Lyson says. "But just like the bird feather did not initially evolve for flight – we now have early relatives of birds such as tyrannosaur dinosaurs with feathers that definitely were not flying – the earliest beginnings of the turtle shell was not for protection but rather for digging underground to escape the harsh South African environment where these early proto-turtles lived."

This digging function may have come in handy for turtles trying to move into aquatic environments and may have even helped them survive the Permian-Triassic extinction, an event that occurred around 252 million years ago that wiped out 90 percent of life on Earth. A study published in 2014 by researchers from the Massachusetts Institute of Technology suggests that this mass extinction event was triggered by the release of methane-releasing microbes into the atmosphere.

The study was published in the journal Current Biology.

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