The anatomy of the Spinosaurus ( Spinosaurus aegyptiacus ) has been a mystery for many decades . A somewhat controversial creature. Scientists had always believed that dinosaurs, in general, were land animals. That none of them swam. It seems we were completely wrong.
This dinosaur, which lived 95 million years ago during the Cretaceous, was quite peculiar: about 15 meters long, seven tons in weight, and an unusually long and flexible tail. Now, the discovery of fossil bones from the tail of a Spinosaurus in southeastern Morocco has unraveled this great enigma, thus rewriting the history of aquatic dinosaurs. The key? Spinosaurus used their enormous tail to swim through rivers like crocodiles, making them the first known aquatic dinosaur.
“This discovery is the nail in the coffin of the idea that non-avian dinosaurs never invaded the aquatic kingdom,” explained Nizar Ibrahim, paleontologist at the University of Detroit Mercy and lead author of the new study in the journal Nature. “This dinosaur was actively chasing its prey in the water and not just standing in shallow water waiting for the fish to arrive.”
Thus, despite the fact that, for a long time, scientists speculated that terrestrial dinosaurs could have lived in aquatic environments, an idea that has been diluted in recent decades, this finding has turned the history of dinosaurs, confirming “unequivocal evidence for an aquatic propulsive structure in a dinosaur.” The Spinosaurus used its colossal fin-shaped tail to move rapidly through rivers and hunt its prey.
The tail fossil is well preserved (80% of the tail was unearthed) and was found in the Kem Kem beds of Morocco. Their examination showed a flexible tail with a series of tall neural spines, so the tail could have moved laterally to create thrust, propelling the predatory dinosaur through the water in a manner similar to the locomotion we see in today’s crocodiles. day or even a modern crested newt.
To test their theory, the researchers used a robotic flapping apparatus to emulate the motion of the recovered specimen, testing the wave forces created by different shapes of tail. The results left no room for doubt: They showed that the shape of the Spinosaurus’ tail was much better equipped for marine environments compared to those of land dinosaurs. This shows that the tail represented an adaptation to an aquatic lifestyle consistent with the fish-based diet that had previously been attributed to this great predator. But it is possible that it could have eaten huge fish, including sharks.
It is the first unequivocal evidence of a specialized tail to move in water. Let’s remember that despite the fact that mosasaurs and plesiosaurs terrorized the ancient oceans of the planet, they are not considered dinosaurs, but reptiles.
“We believe that this discovery revolutionizes our understanding of dinosaur biology,” says Stephanie Pierce, co-author of the work.
Curiosity: The Spinosaurus is a famous dinosaur. We have been able to see it in movies like Jurassic Park III, which presents it to us as the largest of the carnivorous dinosaurs.
Referencia: Ibrahim, N., Maganuco, S., Dal Sasso, C. et al. Tail-propelled aquatic locomotion in a theropod dinosaur. Nature (2020). https://doi.org/10.1038/s41586-020-2190-3
