Turtle 'Tree of Life' Shows Relation to Dinosaurs
A newly constructed and detailed turtle "tree of life" shows how these reptiles are related to one another, to other reptiles, and even to dinosaurs, according to a new study.
The evolutionary history of turtles has been a highly debated topic among scientists for decades, but thanks to a new genetic sequencing technique called Ultra Conserved Elements (UCE), researchers from the California Academy of Sciences (CAS) are finally beginning to unravel the clues indicating their closest relative in the animal kingdom. They hope their high-tech methods can revolutionize the way scientists explore species origins and evolutionary relationships, as well as provide a unique way for analyzing future fossil records.
"Calling this is an exciting new era of sequencing technology is an understatement," researcher Brian Simison said in a press release.
"In the space of just five years, reasonably affordable studies using DNA sequencing have advanced from using only a handful of genetic markers to more than 2,000 - an unbelievable amount of DNA," he added. "New techniques like UCE dramatically improve our ability to help resolve decades-long evolutionary mysteries, giving us a clear picture of how animals like turtles evolved on our constantly-changing planet."
Previous belief was the turtles were most closely related to lizard and snakes, also of the reptile family. However, the new data more accurately places turtles in the newly named group "Archelosauria," along with their actual closest relatives: birds, crocodiles, and even dinosaurs, the largest animals ever to walk the planet.
Softshell turtles, in particular, have always been particularly difficult to place on the reptile tree of life. They are bizarre, scaleless turtles with snorkel-like snouts that are supposedly linked with a smaller semi-aquatic group called mud turtles.
But it's not surprising, given their unique looks, that after the CAS team used the UCE technique that they turtles were placed in a league of their own, far removed from any turtle relatives.
Fossil records are notorious for painting an inaccurate picture of turtle relationships, but the new findings change that. With the new turtle tree of life bringing more clarity to the evolutionary history of these slow-moving, shelled reptiles, scientists can better compare them not only across species, but across continents as well.
The findings are described in the journal Molecular Phylogenetics and Evolution.
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