How The Turtle Got Its Shell
Paleontologists believe they may have finally solved the mystery of how turtles developed their shells, thanks to a discovery of fossils, dating back 220 million years.
Chun li, a student at the Chinese Academy of Sciences found the three almost perfect, turtle fossils in Southern China's Guizhou province. What was even more exciting however, was the fact that these fossils had features like teeth and an incomplete shell, something that had never been found in turtle fossils before.
Over the years, two theories on how shells were formed have been developed, but until these fossils were found there had been no way to verify which one was accurate.
Some scientists believed that the shell had formed from the backbone and ribs. However, others believed that the shell grew from the skin and then fused with the underlying ribs and backbone.
After studying the latest specimens, scientists have come to the conclusion that first theory is the correct one. They believe that the lower shell formed first and then as the ribs and backbone expanded, they grew and covered it to form the outer hard shell. A similar phenomenon has been observed when the shell forms in a turtle embryo.
Though the fossil, which have been named Odontochelys Semitestacea or half-shelled turtle with teeth, did not have a fully developed top shell, it did have a fully-formed shell on the underside that helped protect its belly. This discovery has led scientists to believe that these creatures were water dwellers and that the underside shell protected them from predators, as they swam in the oceans.
Sources: Dailymail.co.uk, Science Daily