Turtle Shells Evolved For Digging, Not Protection

Turtles shells, given their protective nature, are assumed to have evolved for the purpose of protection. That may not be the case, however, at least according to a newly published study. Though shells do provide protection for modern turtles, researchers believe the earliest instances of these shells were used for burrowing, not withstanding the jaws of a predator. Burrowing underground would have enabled the turtles to avoid harmful exposure in the South Africa environment where they lived.

Evidence for this comes from the proto-turtle Eunotosaurus africans, which was partially shelled and existed in South Africa's Karoo Basin. Two fossils of this proto-turtle were discovered by University of Witwatersrand's Dr Roger Smith and Dr Bruce Rubidge, both of whom were among the co-authors for the study. Joining their fossils was another particularly well-preserved proto-turtle fossil found by a young boy.

The fossil found by the boy is said to be 15cm in length and to have been preserved enough to have "fully articulated hands and feet," not to mention its skeleton. This specimen is said to have ultimately made the study possible, and helped shed light on the early purpose of the turtle shell.

Researcher say the earliest evolution toward the turtle shell was a broadening of the ribs, which slowed the turtle down and diminished its breathing capacity, but aided in digging by stabilizing the body so that the forelegs could dig with powerful movements. These evolutionary adaptions are also believed to have help move turtles into "aquatic environments," the combination of which may have helped the creature avoid extinction during the Triassic period.

Via: EurekAlert