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The scientists nicknamed the fossils "Turtwig"

Photo: Fabiany Herrera; Héctor Palma-Castro / EurekAlert!

For Father Gustavo Huertas, it was already a beautiful find about fifty years ago: near the town of Villa de Levya, the Colombian priest was collecting rocks and fossils, and one day he came across two small, round chunks patterned with lines. Leaves, thought the padre, and classified the finds as fossil plants.

But the clergyman was wrong, as a study published in the journal "Palaeontologia Electronica" shows: The alleged plant parts are in fact the fossilized remains of baby turtles. The fossils come from rocks from the early Cretaceous period, i.e. from 132 to 113 million years ago, the time of the dinosaurs.

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Photo: Fabiany Herrera; Héctor Palma-Castro / EurekAlert!

In 2003 (i.e. years after the discovery), Huertas had classified the fossil presumed leaves as Sphenophyllum colombianum – which recently made other scientists suspicious, as the other known members of the genus Sphenophyllum had already become extinct more than 100 million years earlier. The site also piqued the interest of Fabiany Herrera, assistant curator of fossil plants at the Field Museum in Chicago, and his student assistant Hector Palma-Castro.

"We went to the fossil collection of the Universidad Nacional de Colombia in Bogotá and started looking at the plants, and as soon as we photographed them, we thought, 'This is strange,'" Herrera is quoted as saying in a statement.

Are these veins of a plant – or rather bones?

At first glance, the fossils, which are about five centimeters in diameter, looked like the fossilized leaves of a plant. But Herrera and Palma-Castro found that important features weren't quite right. "If you look at the fossil in detail, the lines don't look like the veins of a plant – I was sure they were bones," says Herrera.

A paleontologist friend, Edwin-Alberto Cadena of the Universidad del Rosario in Bogotá, confirmed the concerns. The structure reminded him of the shell of a turtle. Further research confirmed the suspicion. The details in the turtle's bones helped researchers estimate the turtle's age at the time of its death: already hatched, but no more than a year old. Such finds are rare, since at a young age the carapace is still thin and can be easily destroyed.

The researchers don't blame Padre Huertas for his mistake – the surviving shells actually resemble fossil plants. But the features that Huertas thought were leaves and stems are actually the fossilized vertebrae that make up a turtle's shell.

The scientists nicknamed the fossils "Turtwig," after a Pokémon that is half turtle, half plant. In Germany, by the way, the corresponding Pokémon is called Chelast, a compound name from the Greek word for turtle chelona and the branch on the tree.