[1/4]This image taken in 2022 shows fossilized cells in Bogotá, Colombia.From Edwin Cadena/Reuters Obtaining license rights
Sept. 28 (Reuters) – DNA remains have been discovered in the fossilized remains of a 6-million-year-old sea turtle, closely related to modern-day Kemp’s ridley turtles and the lesser sea turtle. Researchers announced Thursday that it was a vertebrate fossil.
Researchers said the fossil, unearthed on Panama’s Caribbean coast in 2015, contained exquisitely preserved bone cells called osteocytes. This fossil had a partial, relatively complete carapace (turtle shell), but no remaining skeleton. The turtle was believed to have been about 1 foot (about 30 centimeters) long when it was alive.
In some bone cells, cell nuclei were preserved and reacted to chemical solutions, allowing researchers to recognize the presence of remnants of DNA, the molecule that carries genetic information for the development and function of living organisms. said lead author paleontologist Edwin Cadena. Research results published in the Journal of Vertebrate Paleontology.
“I would like to point out that we did not extract the DNA; we were only able to recognize the presence of DNA traces in the nucleus,” said Cadena, of Bogotá’s Rosario University and the Smithsonian Tropical Research Institute. added.
DNA is highly perishable, but under the right conditions it can be preserved in ancient ruins. Last year, researchers reported the discovery of animal, plant and microbial DNA from around 2 million years ago in sediments in the northernmost tip of Greenland.
Cadena said similar DNA remains have been found in fossils of vertebrates older than the newly described turtle, including a tyrannosaurus that lived about 66 million years ago and a tyrannosaurus that lived about 78 million years ago. The only two species of dinosaurs that existed were Brachylophosaurus. Cadena said DNA remains have also been reported from insects that are tens of millions of years old.
Cadena said the turtle belongs to the same genus Lepidocheris as two of the seven species of sea turtles in the world: Kemp’s Ridley and Olive Ridley, the world’s smallest sea turtles. The Kemp’s Ridley, with its triangular head and slightly hooked bill, is found primarily in the Gulf of Mexico. The Olive Ridley is very similar to the Kemp Ridley and is more widespread, living primarily in tropical regions of the Pacific, Indian, and Atlantic oceans.
The fossil is the oldest known member of Lepidocheris and will help shed light on the poorly understood evolutionary history of the genus, the researchers said. Cadena said the remains were too incomplete to identify each species.
“Each fossil, each fossil part, has specific preservation requirements, and in some cases it may be advantageous to preserve the original biomolecular remains, such as proteins or DNA,” Cadena said.
“Perhaps in the future, with more studies of this kind, we could at some point sequence very small DNA fragments and make inferences about their relatives and incorporate that information into broader molecular evolutionary studies. “It could become something like that,” Cadena added.
Reporting by Will Dunham in Washington. Additional reporting by Elida Moreno.Editing: Rosalba O’Brien
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