Oldest sea turtle ancestor hailed from southeastern U.S.

BIRMINGHAM, Ala., Oct. 4 (UPI) -- The grandfather of all modern marine turtles hailed from the Deep South. New research suggests the species Ctenochelys acris was the patriarch of the lineage that yielded the green sea turtle, Kemp's ridley, the loggerhead and many others.

Until recently, paleontologists weren't convinced that Ctenochelys acris was a unique species. They had only a handful of fossil fragments. But the recovery of two near-complete skeletons in Alabama has offered some clarity.

The recent survey of Ctenochelys acris fossils -- detailed in the Journal of Systematic Palaeontology -- confirms the distinctiveness of the species and also links it with modern sea turtles. Scientists believe Ctenochelys acris is the oldest known ancestor of today's marine turtles.

The rocks from which the fossils were recovered suggest Ctenochelys acris lived roughly 80 million years ago during the Late Cretaceous period.

Ctenochelys acris lived among the coastal shallows, carving out a niche during the peak of sea turtle diversity.

"This animal was a bottom-dwelling sea turtle that fed primarily on mollusks and small invertebrates," Drew Gentry, a biology doctoral student at the University of Alabama at Birmingham, explained in a news release. "Unlike the 'rudder-like' hind-limbs of today's sea turtles, C. acris had large, powerful hind-limbs to help push it through the water, a lot like a modern-day snapping turtle."

"Data from C. acris tell us not only that marine turtles are capable of occupying specialized oceanic niches," Gentry added, "but also that many of the sea turtles we know today may have gotten their evolutionary start as something similar to an oversized snapping turtle in what eventually became the southeastern United States."

Researchers hope further analysis of Ctenochelys acris fossils, and the fossils of its relatives, will yield new insights into how sea turtles adapted to changes in the environment. Such insights might help scientists better understand how climate change will affect modern sea turtles.