Study details slow but steady pace of brain evolution in turtles

Feb. 1 (UPI) -- For turtles, slow and steady isn't just a racing strategy. It's also an approach to brain evolution.

According to a new study published this week in the journal Frontiers in Ecology and Evolution, the turtle brain has been evolving at the same slow pace for the last 210 million years.

Fossil turtles look very much like model turtles, suggesting the reptiles are largely unchanged. Most efforts to understand turtles' evolutionary history have focused on postcranial adaptations -- everything but the skull.

In the latest study, scientists focused exclusively on the brain cases of turtles.

Researchers began by imaging two fossil skulls belonging to Proganochelys quenstedti, the first title species with a fully formed shell. The species lived 210 million years ago during the Jurassic period.

Using the tomography scans, scientists generated a 3D digital model of the early turtle's brain. They compared the brain to models of modern turtle brains.

"Our results demonstrate that Proganochelys, the oldest turtle with a real shell, had a very simple brain structure," lead study author Stephan Lautenschlager, professor at the University of Birmingham, said in a news release. "Vision and hearing were probably not very good, while the sense of smell was moderately developed."

Over the past 210 million years, the turtle brain has diversified. Slowly but surely, it has helped species adapt to a variety of habitats and survival strategies.

"Over a period of 200 million years the brain of turtles became more complex, allowing them to adapt to different habits and living conditions," said Ingmar Werneburg, a researcher at the University Tübingen in Germany. "This is very important as we see similar diversifications in other animal groups such as mammals and birds."

According to the new analysis, the first turtles were land-dwellers. It was only as they evolved and diversified that turtles species began to branch out and explore new watery habitats.

The slow and steady nature of turtles and their evolutionary and metabolic approach is likely an important part of their resilience and longevity. Turtles are the oldest reptile group, surviving several major extinction events. Some modern turtle species live well into their hundreds.