A fossil found in South America is of the oldest sea turtle ever found, researchers say, at least 25 million years older than the previous record-holder.
More than six feet long, the turtle, Desmatochelys padillai sp., lived around 120 million years ago, they say.
The "almost completely preserved skeleton" was found in 2007 in central Colombia and dated to the Cretaceous period based on its physical features and the age of the sediments in which the fossil was found, the researchers report in their published study of the creature appearing in the journal PaleoBios.
The age is significant, the researchers say; sea turtles descended from both terrestrial and freshwater turtles beginning about 230 million years ago, but during the Cretaceous period, they split into land- and sea-dwelling varieties.
With few fossil discoveries from the period, the exact timeline of the split has been difficult to pin down, the researchers say.
"This lends a special importance to every fossil discovery that can contribute to clarifying the phylogeny of the sea turtles," says Edwin Cadena from the Senckenberg Research Institute in Frankfurt, Germany.
The new find represents the oldest confirmed record of sea turtles anywhere in the world, says Cardena and study co-author James Parham of California State University, Fullerton.
The new fossil adds to knowledge of sea turtle evolution and adds to growing evidence that turtles moved into the world's ocean waters several times during the age of the dinosaurs, they say.
Examination of the fossil's characteristics has placed the creature in the turtle group Chelonioidea, a group that lives in tropical and subtropical oceans.
Today, the group includes the modern Hawksbill Turtle and the Green Sea Turtle.
Parham studied turtle fossils in the collection of the University of California Museum of Paleontology discovered as long ago as 1945, as well as the samples from Columbia.
"I was familiar with the material at the museum, but it wasn't until the new specimens from Colombia were discovered that it became apparent that these specimens were as old as they were," he says.
In addition to increasing understanding of sea turtle evolution, the research shows the importance of museum specimens, he says.
"Our study demonstrates how fossils collected 70 years ago can make important contributions to our understanding of life on Earth," he says.
