Evolution meandered back and forth 390 million years ago. Some four-link creatures left the ocean and ventured to the surface of the earth. They are the ancestors of amphibians, reptiles, birds and mammals. Evolution took its course and many of these animals were comfortable on dry land. Or they decided, like dolphins and whales, to return to the sea permanently. But not just them. Also Thalatosuchians, Jurassic ancestors of modern crocodiles. They returned to the sea about 180 million years ago: when crocodiles were sailing in the sea.
They were predators up to ten meters long. They were probably breathing through their noses rather than through the vents. They had the smooth skin and body shape of modern whales and dolphins. His limbs became fins. They rationalized their bodies and developed wavy tails to be able to cross the waves. But not only that. They have also adapted their inner ear to life in the sea, as researchers from the University of Edinburgh have found.
From sea and land
They explain it in a new study published in the journal "Proceedings of the National Academy of Sciences (PNAS)". They examined the ears of 18 extinct and 14 modern reptiles, particularly a rigid structure of the inner ear called the labyrinth of bones. This affects the balance and spatial orientation. The results showed that these old crocodiles developed thicker ear canals. Also a smaller and more compact labyrinth of bones when they came into the sea. “Changes in the shape of the channel are better adapted to life in the oceans, where the buoyancy can support an animal. A highly sensitive sense of balance is required on Earth to deal with gravity and complex landscapes. “The claim comes from palaeontologist Julia Schwab, who is responsible for the research.
These animals were confined to flat coastal areas and sometimes the open sea and dived deep. Something similar happened in the ears of the whales when they were submerged about 50 million years ago. But the old whales adapted very quickly to the ocean. Thalatosuchians have spent millions of years in and out of the water. This difference can be due to the fact that alligators lay eggs and have to go to the ground. The crocodiles sailed in the sea but missed the land.
Convergent evolution
The similarities between the whale's inner ear and the Thalatosuchian are an example of a phenomenon called convergent evolution. Dissimilar organisms independently develop similar properties. For example, the wings of birds, bats, and extinct flying reptiles called pterosaurs.
"The Thalatosuchians are one of the strangest groups of animals that have ever existed. I'm surprised they don't get more attention," says paleontologist and co-author Steve Brusatte. .. – which allowed them to move in the water and become better swimmers, only later did their ears change as their sensory systems had to evolve to keep up.
The team plans to investigate other features of the Talatosuchio. It is a great example of evolution that also shows us the way forward.
