Turtle didn’t develop shells for protection, but for digging – research
According to a new study, “Fossorial Origin of the Turtle Shell,” turtles’ shells were originally developed to help them burrow underground, not to offer protection as we previously thought.
An international group of paleontologists have found the ribbed proto shell on the earliest turtles evolved to allow the creatures to dig their way underground in order to escape the harsh South African climate.
Dr. Tyler Lyson, the study’s lead author, explained: “Just like the bird feather did not initially evolve for flight, 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."
The scientists used a 15cm fossil of a 260 million-year-old proto turtle, the Eunotosaurus Africanus from South Africa’s Karoo Basin. The fossil was discovered by an eight-year old boy who uncovered it on his father's farm in South Africa’s Western Cape.
The fossil was found to have distinctly broadened ribs, which gave the turtles a stable base to dig from.
"We knew from both the fossil record and observing how the turtle shell develops in modern turtles that one of the first major changes toward a shell was the broadening of the ribs," Lyson said.
Ribs are used to support the body during movement and help ventilate the lungs. Broadened ribs restrict movement of the torso and slow the animal down, hence turtles’ reputation for being slow.