(CNN) — A new study reveals that ancient plant fossils that have baffled scientists turn out to not be plants after all.
Instead, these small, round shapes were the shells of baby turtles that lived during the time of the dinosaurs. Scientists have named this type of turtle “Turtwig”, after the Pokémon character who is half turtle and half plant.
According to the study’s authors, this is the first time that small turtle shells have been found in northwestern South America.
The results of their research were published Thursday in the journal Electronic paleontology.
“In the world of Pokemon, one encounters 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, you immediately think of some Pokemon. In this case, Turtwig“A little turtle with a leaf hanging on its head.”
But it took some research to solve this fossil mystery that began decades ago.
Wrong place, wrong time
It all started when Colombian priest Gustavo Huertas discovered fossils in the Baja Formation. The formation is part of a geological heritage site in Colombia called Lagerstätte de Reptiles Marinos del Ricaurte Alto.
Fossils previously discovered at the site include dinosaurs, plesiosaurs, ichthyosaurs, turtles and relatives of crocodiles called crocodilians, dating back to the Early Cretaceous period, between 113 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, and when he found rocks with leaves, he considered them a fossil plant. Huertas described the specimens as Sphenophyllum colombianum in a 2003 study.
But other scientists were surprised to learn that the plant was discovered in northern South America and dates back to between 113 and 132 million years ago. According to fossil records, this extinct plant, which once spread around the world, became extinct more than 100 million years ago.
Previous research on the plant showed that its leaves are wedge-shaped with veins emerging from the base of the leaf.
The age and location of the fossils piqued the interest of 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 the Early Cretaceous (100.5 to 145 million years ago) of northwestern South America, a part of the continent where little research on ancient plants is done.
Both fossils, about 5 centimeters in diameter, were in the collections of 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 looked in detail, the lines visible in the fossils did not look like plant veins: I was sure they were most likely bones,” Herrera, the study’s lead author, says in a press release.
Solve the fossil puzzle
Herrera contacted his colleague Edwin Alberto Cadena, a senior professor 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 definitely looks like a carapace, the bony upper part of a turtle’s shell,'” Cadena, co-author of the study, explains in a statement. “I said, ‘Well, this is unusual, because it’s not only a turtle, it’s a newborn specimen, it’s very, very small.’
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 little concave, like a bowl. At that moment we realized that the visible part of the fossil was the other side of the shell, 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 a year old when they died.
According to Competa Romero, as baby turtles develop, their growth rates and sizes can vary. But the remains of baby turtles are rare to find because the bones in their shells are so thin.
“These turtles were likely relatives of other Cretaceous species reaching 4.5 meters in length, but we don’t know much about how they reached such huge sizes,” Cadena said in a statement.
The researchers did not blame Huertas for misclassifying the fossils as plants. What were thought to be leaves and stems were actually the vertebrae and ribs of a tortoise shell.
“We have solved a small mystery related to ancient plants, but the most important thing is that this study demonstrates the need to re-examine historical collections in Colombia. The Early Cretaceous is a critical time in the evolution of land plants,” Herrera said.
The research team’s next goal is to discover the forests that once grew in the area.
“In paleontology, imagination and the ability to be amazed are always tested,” Palma-Castro said. “Discoveries like this are truly special because they not only expand our knowledge of the past, but open a window into the different possibilities of what we can discover.”
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