Whales are considered as the largest animal in the present, but before that, the ancient Megalodon sharks ruled the seas, and they are believed to have led whales to grow in size.

According to a report from Tech Times, the Megalodon sharks are the largest sharks known to have ever lived, with each tooth measuring up to seven inches. These mega sharks are also thought to be the most fearsome killers in the ocean before their eventual extinction.

Researchers at the University of Florida and University of Zurich revealed what made the 60-foot long Megalodon sharks to go extinct in the journal PLOS ONE. The researches utilized Optical Linear Estimation (OLE) and discovered the exact date when the Megalodon sharks perished, Capital Wired reported. The researchers identified the records of the 42 most recent fossils by using the Paleontology Database, a large online compilation of fossil data.

The technique doesn't exactly pinpoint the exact date of the extinction of the great sea creature, but statistically, it dates back to the "middle Miocene Epoch (15.9 million to 11.6 million years ago) and the Pliocene Epoch (5.3 million to 2.6 million years ago)," according to The Economic Times. These epochs are the time when baleen whales started growing in size and the Megalodon sharks began dying out.

Tech Times adds that the extinction of the Megalodon sharks, which preyed mainly on dolphins, whales, and other marine creatures, caused the ancient baleen whales to thrive in size. Because of the lack of competition, the ancient whales flourished.

"Our results suggest that C. megalodon went extinct around 2.6 Ma.," according to the researchers as cited by Tech Times.

"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," the report adds.

Catalina Pimiento, a study researcher from the department of biology at the University of Florida, says that the study paved way for the researchers to better understand the implications when a predator disappears entirely from the top of the food chain.

"When you remove large sharks, then small sharks are very abundant and they consume more of the invertebrates that we humans eat. 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," Pimiento said in the Tech Times report.