A team of experts from the California Academy of Sciences has created a detailed evolutionary tree of turtles, including them in a new group of animals called Archelosaurs , along with birds, crocodiles and dinosaurs.
After decades of experts have debated the relationship between turtles and other reptiles such as lizards and snakes, a state-of-the-art genomic sequencing technology has generated new data of genetic information that prompts to reconsider the biological history of these animals.
The research, which appears in Molecular Phylogenetics and Evolution , estimates that the new technique – dubbed Ultra Conserved Elements (UCE) – allows us to reveal the closest relatives of turtles in the entire animal kingdom.
The study has also solved an evolutionary mystery surrounding the so-called softshell turtles, a rare group of these animals that have a snorkel-like trunk, long neck, and a thick soft shell of leather-like skin. Until now, studies linked these turtles to a smaller semi-aquatic group called mud turtles, even though softshell turtles appear in the fossil record long before these other turtles.
Now, instead, softshell turtles have to be placed quite a distance from any relative of turtles on the tree of life. Its long independent history would help explain its striking appearance, as well as its ancient presence in the fossil record. Another of the elements of turtles intriguing to science has been their shells.
In this sense, last year, a team of researchers from the National Museum of Natural History under the Smithsonian Institution (USA) determined that the formation of the turtle shell began about 40 million years earlier than previously thought . The oldest fossil turtle with a shell like the current ones dates back to about 210 million years.
