14 DAY TRIAL // Newly discovered bone fragments sprung intense debates among paleontologists, who now believe that the common turtle evolved to its current state over 200 million years of evolution, from some form of lizard that looked pretty much like an armadillo. The 210 million year old fragments, found at a site in New Mexico, reveal a lizard that has a 1 mm thin carapace. Scientists now believe that this is the missing link between lizards and tortoises.
Until now, turtles were believed to have evolved from a separate class of animals and that land lizards played no role in it. But according to Walter Joyce, a paleontologist at the Peabody Museum of Natural History in New Haven, Connecticut, who made the discovery, the new fossil seems to indicate that "Triassic turtles are few (...) probably because they lived on land, where fossilization is far less likely to happen." Spencer Lucas, of the New Mexico Museum of Natural History and Science in Albuquerque, who uncovered the first bone fragment about 10 years ago, argues that the new digs finally prove his theory correct.
The fossils of Chinlechelys tenertesta (thin-shelled turtle in Latin), a terrestrial lizard, about 30 cm (1 feet) long, are considered to be the first discovered remnants of the species that first developed a carapace. In other words, it's most likely that these little creatures were the first tortoises to have ever lived. Tough its back shell is extremely thin, scientists found out that not all its vertebrae were linked to the carapace, unlike in other old fossils discovered at various digging sites.
The thing that puzzles scientists at this point is why the turtles developed their protective shell and why they haven't evolved as fast as the other species on Earth. According to the data currently available, the turtle "blueprint" hasn't changed much in about 200 million years. The only things that evolved were its size, mass and shell thickness. But essentially, tortoises are still the closest living things to dinosaurs.