Hunters of the seas, sharks seem to be the surviving champions. This is according to a study published in the journal Scientists at Uppsala University in Sweden PLOS Biology. According to them, the asteroid that crashed into the Gulf of Mexico 66 million years ago destroyed almost all life, including land and water. Dinosaurs, Has almost no impact on sharks.
In-depth analysis of 1,239 shark teeth
To this end, they examined 1239 fossil teeth belonging to nine Shark species Is different (these eight species still exist, one is extinct). These teeth date from 83.6 million to 56 million years ago.
“Sharks are iconic sea predators that have survived many mass extinctions over geological times.”Says Mohamed Bassi, one of the authors of the study. These animals, which are at least 450 million years old, have no nickname “Living Fossils”, Due to their great durability. To illustrate this survival, experts present the shark’s highly resistant immune system and its ability to repair its own DNA.
Unlike many other animal species, sharks are made of cartilage, not bones. Because cartilage is less hard, it usually does not resist fossils. This is why scientists have conducted a study based on shark teeth.
The sharks embraced
Although the sharks have not disappeared, they have not been embraced. Especially with the triangular blade-shaped teeth – some groups of predatory apes – suffered selective extinction during this period, perhaps because they were missing prey animals. In contrast, other lines have increased over time.
“This pattern of selective extermination may reflect environmental change from predatory tetrapods that specialize in specific prey to highly predatory animals.”Dr. Bassi said. Before adding it “Shark diversity is not affected when dinosaurs are exterminated”.
The scientist concludes: “Finally, our study reveals a complex morphological response to the end of the Cretaceous mass extinction. It highlights an event that affected the evolution of modern sharks.”.
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