Whales are the largest living animal today and it appears that the extinction of the 60-foot-long Megalodon shark had something to do with whales growing to their present-day size.
The Megalodon (Carcharocles megalodon) was a fearsome predator of the ocean. It was the largest shark known to have ever lived, with teeth measuring nearly seven inches. It is not yet clearly known what caused the Megalodon to become extinct but researchers now have a better idea of when this happened.
In a new study published in the journal PLOS One on Oct. 22, researchers looked at the records of 42 of the most recent fossils of the ancient shark and employed a technique known as Optimal Linear Estimation (OLE) to determine when this animal died out.
The researchers found that the fearsome predator of the ancient ocean likely died out approximately 2.6 million years ago. The Megalodon's extinction likely happened in the period between the Pliocene and Pleistocene epochs, the time when the baleen whales started to grow to their now gigantic sizes.
Baleen whales, which feed on tiny animals that they filter out of the water using their baleen, the comb-like structure in their mouth, include the blue whale, the biggest animal known today, which can grow over 89 feet in length.
The timing of the Megalodon's extinction is plausible because the carnivorous animal preyed on dolphins and whales and its absence would have paved way for the primitive baleen whales, which were smaller compared with their counterparts today, to flourish.
"Our results suggest that C. megalodon went extinct around 2.6 Ma.," the researchers wrote. "Furthermore, when contrasting our results with known ecological and macro-evolutionary trends in marine mammals, it became evident that the modern composition and function of modern gigantic filter-feeding whales was established after the extinction of C. megalodon."
Study researcher Catalina Pimiento from the department of biology at the University of Florida in Gainesville said that the results offer a basis for researchers to understand the implications of the declining population of the world's top predators, including large sharks.
"When you remove large sharks, then small sharks are very abundant and they consume more of the invertebrates that we humans eat," Pimiento said. "Recent estimations show that large-bodied, shallow-water species of sharks are at greatest risk among marine animals, and the overall risk of shark extinction is substantially higher than for most other vertebrates."
