A Smithsonian scientist and colleagues have discovered evidence that suggests that turtles began to develop shells 40 million years earlier than previously believed.
Scientist have always been fascinated about how and when turtles began to develop shells over their bodies, and till date researchers have not been able to zero in on any concrete time frame. However, a Smithsonian scientist and colleagues have discovered evidence suggesting that turtles first began to develop shells 40 million years earlier than previously believed.
The oldest fossil turtle discovered, dates back to 210 million years. However, the fossil was found with a fully developed shell and hence, provided no clues as to when the shell first developed. However, in 2008 when a 220 million-year-old fossil was discovered in China, scientists revealed that they might have just found a tiny clue about the development of turtle shells. Though the fossil discovered in 2008 had a fully developed plastron, it had only a partial carapace made up of distinctively broadened ribs and vertebrae on its back. The species was named Odontochelys semitestacea.
After this, scientists moved their focus to studying a newly discovered South African species of Eunotosaurus africanus, which was 40 million years older than the Odontochelys semitestacea species.
They found that Eunotosaurus shared many features that were found only in turtles, which indicated that this species was one of the first of the evolutionary branch of turtles.
"Eunotosaurus neatly fills an approximately 30-55-million year gap in the turtle fossil record," Tyler Lyson, a Peter Buck Postdoctoral Fellow at the Smithsonian's National Museum of Natural History, said in a press release."There are several anatomical and developmental features that indicate Eunotosaurus is an early representative of the turtle lineage; however, its morphology is intermediate between the specialized shell found in modern turtles and primitive features found in other vertebrates. As such, Eunotosaurus helps bridge the morphological gap between turtles and other reptiles."
The findings of the study are published online in the journal Current Biology, May 30.
