Why did underwater volcanic eruptions make modern sharks more ferocious?

the Underwater volcanic eruptions Which happened about 93 million years ago It had a huge impact on development Sharks accidentThis is according to a recent study published in the magazine Current biology. These eruptions caused a massive increase in carbon dioxide levels, causing climate change that significantly raised ocean temperatures.

This change in the marine environment was crucial to the evolution of sharks. Scientists have discovered this These conditions caused sharks to develop pectoral fins. A research team measured more than 500 fossilized sharks and shark species, concluding that their fin shapes were narrow and elongated to adapt to the open ocean, not just the seafloor. “Pectoral fins are an important structure, similar to our arms.” to explain Philip Stearnsa doctoral student at the University of California, Riverside, and first author of this paper.

During the period Cretaceous periodOcean surface temperatures were much higher than they are today. While sea temperatures today average around 20°C, at that time they averaged 28.3°C. This extreme heat, which did not happen overnight, has led to changes in sharks that previously lived mainly on the sea floor, establishing themselves as more efficient predators in open waters.

The evolutionary process that turned these sharks into the fast and ferocious predators we know today is best understood by looking at their pectoral fins, which resemble the wings of commercial airliners. “Their fins are like the wings of commercial aircraft, long and narrow, to reduce the amount of energy needed for movement.”Stearns said.

Today, most shark species still live on the ocean floor, in what scientists call the ocean floor Benthic. These benthic species are generally slender, flat, medium-sized predators, very different from the speedy, open-water sharks that inspire popular culture. Only about 13% of modern sharks are these fast predators.

Researchers believe that ancient sharks faced respiratory problems due to low oxygen levels on the seafloor during the Cretaceous period. This has led some to adapt to open waters that are less oxygen-dense. ““During the Cretaceous period, sea surface temperatures were much warmer than they are today,” said Lars Schmitz, co-author of the study and a professor at Claremont McKenna College. “Open ocean surface temperatures were fairly warm throughout that epoch, and then a distinct peak occurred over a period of one to two million years.”

Global warming at that time not only fueled the evolution of sharks, but also caused the extinction of other marine species that were unable to adapt to the new conditions. However, predicting how sharks and other marine life will respond to current global warming trends is difficult. Tropical sharks such as the tiger shark and bull shark have been observed moving north. “The temperature is rising so rapidly now that there is nothing in the geological record that I know of that we can use to make a real comparison,” Stearns said.

The responses of marine life to current climate changes are uncertain and complex, a constant concern for biologists and conservationists. The study highlights this complexity and highlights the importance of continuing to study how marine species adapt to rapid climate changes.