Evolution is the way of life, and that's exactly what scientists expected to see in the turtle too. Earlier presumptions that the turtle developed its shell over the years, to protect itself, may not be true; now that a team of researchers finally discovered that the turtles may have been living in shells much earlier than that previously thought.
This research, published in the journal Current Biology, explains how turtles may have been living in shells around 40 million years earlier than expected.
Being the only animals to show a fusion of modified ribs, shoulder girdle bones and vertebrae, the turtles are considered to be one of the most unique creatures on Earth; and probably the most controversial too.
For years, there's been a lot of ink spilled, and this new study, may finally put an end to it all.
Researchers had discovered what they thought to be the oldest known fossil turtle back in the year 2008, which they estimated to be around 220 million years old. This fossil turtle, Odontochelys semitestacea, helped scientists learn that the turtle did have a fully developed plastron (the belly portion).
Yet another specimen - Eunotosaurus africanus - was discovered in South Africa expected to be 40 million years older than the one previously discovered. Careful study revealed that it shared may features found only in turtles, such as the absence of intercostals muscles (muscles that run between the ribs), paired belly ribs and a special form of rib development, making them the first species to form the evolutionary branch of turtle.
"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.
"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."
Since the ribs play a major role in respiration, the team's next challenge is expected to be the examination of the novel respiratory system in turtles, and to see how they evolved in conjunction with the evolution of its shell.
