Shell Puzzle: An Additional Piece Added to the Evolution of Turtles

Related Articles

Related Articles

The origin of turtles is among the most debated topics in evolutionary biology. In a recently published study by Senckenberg scientist Ingmar Werneburg, in cooperation with an international research team, refutes existing hypotheses and sheds a new light on the evolution of the skull architecture.

The results indicate a close link between skull evolution and the highly flexible neck of these armored reptiles.

In addition to their shell, turtles are characterized by their flexible necks and small heads. “Although turtles belong to the reptiles, their skulls differs markedly from those of other members of this group, which – together with their unique armored skeleton – makes it difficult to assess their phylogenetic origin,” explains PD Dr. Ingmar Werneburg of the ‘Senckenberg Centre for Human Evolution and Palaeoenvironment (SHEP) an der Universität Tübingen’.

 

Fossils suggest that several modifications during turtle evolution drove the initially mobile skull to transform to a rigid structure. In this process, the temporal openings behind the eyes closed as well, forming a so-called anapsid skull, which is not found in any other living reptile.

At the same time, the animals developed a unique arrangement of their jaw muscles, comparable to a pulley system. “Until now, it was assumed that these modifications led to an increased bite force in turtles, and that this development constituted a functional adaptation to a modified feeding behavior,” adds Werneburg.

This hypothesis was now tested for the first time under biomechanical aspects by an international research team led by Werneburg. The scientist from Tübingen comments as follows: “To our surprise, the results do not show any support for an increased bite force – neither due to the skull’s rigidity nor caused by the rearranged jaw musculature.” However, the analyses reveal that the evolutionary innovations led to an optimized skull structure, which can withstand higher stress loads while requiring less bone material.

“We combined our new findings with the previous paleontological and anatomical knowledge, allowing us to develop a new scenario,” explains Werneburg. The key feature in this scenario is the close link between the evolution of the skull and the highly flexible neck. “We assume that the skull of modern turtles is the result of a complex process that has been taking place since the emergence of the shell.” On the one hand, the neck movement facilitates a general increase in the animal’s mobility, which counteracts its otherwise rigid body. On the other hand, the option of retracting the neck serves as an additional protective mechanism in dangerous situations.

Moreover, the modifications in the turtles’ skull may not only have led to an improved stress distribution but may also have paved the way for the evolution of new species. “The evolutionary potential for a novel skull architecture and longer, more flexible necks enabled the development of a larger diversity among turtles during and after the Jurassic period,” adds Werneburg in closing.

Senckenberg Research Institute and Natural History Museum

Header Image – Reconstruction of the turtle Proganochelys quenstedti at Naturkundemuseum Stuttgart. Foto: I. Werneburg

Download the HeritageDaily mobile application on iOS and Android

More on this topic

LATEST NEWS

Camulodunum – The First Capital of Britannia

Camulodunum was a Roman city and the first capital of the Roman province of Britannia, in what is now the present-day city of Colchester in Essex, England.

African Crocodiles Lived in Spain Six Million Years Ago

Millions of years ago, several species of crocodiles of different genera and characteristics inhabited Europe and sometimes even coexisted.

Bat-Winged Dinosaurs That Could Glide

Despite having bat-like wings, two small dinosaurs, Yi and Ambopteryx, struggled to fly, only managing to glide clumsily between the trees where they lived, according to a new study led by an international team of researchers, including McGill University Professor Hans Larsson.

Ancient Maya Built Sophisticated Water Filters

Ancient Maya in the once-bustling city of Tikal built sophisticated water filters using natural materials they imported from miles away, according to the University of Cincinnati.

New Clues Revealed About Clovis People

There is much debate surrounding the age of the Clovis - a prehistoric culture named for stone tools found near Clovis, New Mexico in the early 1930s - who once occupied North America during the end of the last Ice Age.

Cognitive Elements of Language Have Existed for 40 Million Years

Humans are not the only beings that can identify rules in complex language-like constructions - monkeys and great apes can do so, too, a study at the University of Zurich has shown.

Bronze Age Herders Were Less Mobile Than Previously Thought

Bronze Age pastoralists in what is now southern Russia apparently covered shorter distances than previously thought.

Legio IX Hispana – The Lost Roman Legion

One of the most debated mysteries from the Roman period involves the disappearance of the Legio IX Hispana, a legion of the Imperial Roman Army that supposedly vanished sometime after AD 120.

Popular stories

Legio IX Hispana – The Lost Roman Legion

One of the most debated mysteries from the Roman period involves the disappearance of the Legio IX Hispana, a legion of the Imperial Roman Army that supposedly vanished sometime after AD 120.

The Secret Hellfire Club and the Hellfire Caves

The Hellfire Club was an exclusive membership-based organisation for high-society rakes, that was first founded in London in 1718, by Philip, Duke of Wharton, and several of society's elites.

Port Royal – The Sodom of the New World

Port Royal, originally named Cagway was an English harbour town and base of operations for buccaneers and privateers (pirates) until the great earthquake of 1692.

Matthew Hopkins – The Real Witch-Hunter

Matthew Hopkins was an infamous witch-hunter during the 17th century, who published “The Discovery of Witches” in 1647, and whose witch-hunting methods were applied during the notorious Salem Witch Trials in colonial Massachusetts.