Remnants of DNA Discovered in Fossilized Sea Turtle
A groundbreaking discovery has been made in the field of paleontology, as researchers have identified remnants of DNA in fossilized remains dating back 6 million years. The fossils belong to a sea turtle closely related to today’s Kemp’s ridley and olive ridley turtles, marking one of the rare instances of genetic material being found in such ancient vertebrate fossils.
The fossils were excavated along Panama’s Caribbean coast in 2015 and are believed to represent a species within the Lepidochelys genus, which includes the Kemp’s ridley and olive ridley turtles. The fossil is partially preserved, with a relatively complete turtle shell, or carapace, but missing the rest of the skeleton. Based on its size, researchers estimate that the turtle would have been about a foot long when it was alive.
The key to this groundbreaking discovery lies in the preservation of bone cells called osteocytes within the fossil. In some of these osteocytes, the cell nuclei were remarkably well-preserved. By treating these cells with a chemical solution, the researchers were able to recognize the presence of remnants of DNA. DNA, the molecule that carries an organism’s genetic information, is typically perishable, but under the right conditions, it can be preserved in ancient remains.
Lead author of the study, palaeontologist Edwin Cadena, emphasized that they did not extract DNA from the fossils, but rather identified traces of DNA within the nuclei of the bone cells. Cadena, who is affiliated with the Universidad del Rosario in Bogota and the Smithsonian Tropical Research Institute, further explained that the findings represent a remarkable breakthrough in understanding the evolutionary history of the Lepidochelys genus.
The discovery of DNA remnants in these ancient sea turtle fossils is significant for multiple reasons. Firstly, it sheds light on the poorly understood evolutionary history of this genus. Additionally, it marks one of the rare instances of genetic material being identified in vertebrate fossils of such great antiquity.
These fossilized remains are now among the oldest-known vertebrate fossils to have been found with similar DNA remnants. Prior to this discovery, the oldest vertebrate fossils with DNA remnants were those of two dinosaurs, the Tyrannosaurus and Brachylophosaurus, which lived about 66 million and 78 million years ago, respectively. DNA remnants in insects dating back tens of millions of years have also been reported.
The Lepidochelys genus includes two of the world’s seven living species of sea turtles: the Kemp’s ridley and the olive ridley. The Kemp’s ridley, known for its triangular-shaped head and slightly hooked beak, is primarily found in the Gulf of Mexico. The olive ridley, which closely resembles the Kemp’s ridley, has a larger distribution and is found in the tropical regions of the Pacific, Indian, and Atlantic Oceans.
While the fossil remains are too incomplete to identify the specific species, their discovery adds valuable information to the poorly understood evolutionary history of the Lepidochelys genus. Cadena expressed hope that future studies may eventually lead to the sequencing of very small DNA fragments, allowing for further insights into the close relatives of these ancient sea turtles.
Cadena highlights that the preservation of original biomolecular remains, such as DNA and proteins, depends on specific conditions at each fossil site. With advancements in research, there is potential for sequencing small pieces of DNA and using that information in broader molecular evolutionary studies.
This groundbreaking discovery has opened up new avenues for understanding the ancient past and evolutionary history of sea turtles. The presence of DNA remnants in these fossils offers a glimpse into the genetic makeup of these ancient creatures and may unlock fascinating insights into their lineage and ancestry.
As researchers continue to delve into the mysteries of the past, discoveries like these bring us closer to unraveling the secrets of our evolutionary origins. The preservation of genetic material in fossils offers a unique opportunity to explore the distant past and gain a deeper understanding of the world that existed millions of years ago.
