Science / Medicine : Fossils Fuel Turtle Mystery

Clues provided by 250-million-year-old fossils unearthed in South Africa have added a new twist to the longstanding scientific mystery of the origin of turtles.

The oldest known turtles date back about 200 million years and have shells and other features similar to modern-day turtles. What has baffled scientists is the apparent lack of animals to fill the 50-million-year evolutionary gap between very primitive reptile-like animals and the appearance of turtles.

Robert Reisz and Michel Laurin of the University of Toronto reported last week in the journal Nature new findings that may point to the animal line that gave rise to turtles. A computer analysis shows that Owenetta, a fossilized, primitive reptile found about 15 years ago near Bethulie, South Africa, appears to be the closest known relative of turtles, Reisz and Laurin said.

Owenetta belonged to a family called Procolophonidae and lived about 250 million years ago. The animals did not have a turtle-like shell and probably looked like small, rather stumpy lizards. However, the makeup of their skulls appears to tie them to modern-day turtles, the researchers said.