Ancient turtle species ‘Turtwig’ was discovered after fossil mystery solved

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news of fascinating discoveries, scientific advances and more.

CNN
—

A new study reveals that ancient plant fossils that baffled scientists turned out to not be plants at all.

Instead, the small, round shapes with a leaf-like pattern were once the shells of baby turtles that lived in the time of the dinosaurs. Scientists have named this type of turtle “Turtwig“, named after the Pokémon character who is half turtle and half plant.

The discovery marks the first time a small turtle’s carapace has been found in northwestern South America, according to the study’s authors.

The results of their research were published Thursday in the journal Electronic fossils.

“In the world of Pokemon, you encounter the concept of combining two or more elements, such as animals, machines, plants, etc.,” said lead author Hector Palma Castro, a graduate student in paleobotany at the National University of Colombia. a permit.

“So, when you have a fossil that was initially classified as a plant, and then it turns out to be a baby turtle, a few Pokémon immediately come to mind. In this case, Turtwig, a baby turtle with a leaf on its head.

But it took some sleuthing to solve this fossil mystery that began decades ago.

It all started when Colombian priest Padre Gustavo Huertas discovered fossils in the Baja Formation. This formation is part of a geological heritage site in Colombia called Marine Reptile Lagerstätte Ricorte Alto.

Previous fossil finds from the site include dinosaurs, plesiosaurs, pliosaurs, ichthyosaurs, turtles and relatives of crocodiles called crocodylomorphs dating from the Early Cretaceous period, between 113 million and 132 million years ago.

Huertas collected fossils and rocks at the site, near the town of Villa de Leyva, from the 1950s to the 1970s. When he found rocks decorated with leaves, he considered them a fossil plant. Huertas went on to describe the specimens as Sphenophyllum colombianum in a 2003 study.

But other scientists were surprised to hear that the plant was discovered in northern South America and dates back to between 113 million and 132 million years ago. The now-extinct plant, which was once widespread around the world, died out more than 100 million years ago, according to the fossil record.

Previous research on the plant showed that its leaves were typically wedge-shaped with veins radiating from the base of the leaf.

The age and location of the fossils intrigued Palma Castro and Fabiani Herrera, associate curator of paleobotany at the Negaunee Center for Integrative Research at the Field Museum of Natural History in Chicago.

Herrera collects and studies plants from Early Cretaceous period (100.5 million to 145 million years ago) in northwestern South America, a part of the continent where little paleobotanical research is conducted.

The two fossils, about 2 inches (5 cm) in diameter, are preserved in collections at the Department of Geosciences at the National University of Colombia. When Herrera and Palma Castro examined and photographed the fossils, they thought something looked strange.

“When you look at it in detail, the lines on the fossils don’t look like plant veins — I was sure they were most likely bone,” Herrera, the study’s senior author, said in a statement.

Herrera contacted his colleague Edwin Alberto Cadena, a senior lecturer and paleontologist who studies turtles and other vertebrates at the Universidad del Rosario in Bogotá, Colombia.

“They sent me the pictures, and I said, ‘This sure looks like a carapace’ — the bony upper shell of a turtle,” Cadena, one of the study’s authors, said in a statement. “I said, ‘Well, that’s great, because this is not only a turtle, but it’s also a very, very small specimen.’

Cadena and one of his students, Diego Competa Romero, of the National University of Colombia, compared the fossils to the shells of other extinct and modern turtles.

“When we first saw the specimen, we were amazed, because the fossil was missing the typical markings found on the outside of a turtle’s shell,” Competa Romero, a co-author of the study, said in a statement. “It was a bit concave, like a bowl. At that moment we realized that the visible part of the fossil was the other side of the carapace, and we were looking at the part of the shell that was inside the turtle.”

While analyzing the shells, researchers determined that the turtles were at most one year old when they died.

As baby turtles develop, their growth rates and sizes can vary, Competa-Romero said. But the remains of baby turtles are rare to find because the bones in their shells are so thin.

“These turtles are likely relatives of other Cretaceous species that reached fifteen feet in length, but we don’t know much about how they actually grew to such gigantic sizes,” Cadena said in a statement.

The researchers did not blame Huertas for mistakenly classifying the fossils as plants. What he thought were leaves and stems were actually vertebrae and rib bones inside the turtle’s shell.

“We have solved a small mystery regarding ancient plants, but more importantly, this study shows the need to re-examine historical collections in Colombia. The Early Cretaceous is a critical time in the evolution of land plants,” Herrera said.

He added that the research team then aims to uncover the forests that were growing in the region.

“In paleontology, your imagination and your ability to be surprised are always being tested,” Palma Castro said. “Discoveries like this are truly special because they not only expand our knowledge of the past, but also open a window into the diverse possibilities of what we can discover.”