In a display of evolutionary prowess, scientists have found that shark decline helped increase the whale population. 

According to researchers from the University of Florida and the University of Zurich, larger filter-feeding whales began to evolve after the decline of the megalodon 2.6 million years ago. The megalodon, an enormous shark, was a top predator that would have preyed on whales.

The team of researchers used Optimal Linear Estimation (OLE) to give the megalodon an approximate extinction date, then studied the whale populations around that time. They noticed that the size and diversity of whales grew exponentially after the removal of their largest predator.

It’s not known why the megalodon went extinct, but fossil records prove that the size of whales grew exponentially following the giant shark’s decline.

According to lead researcher Catalina Pimiento of the Florida Museum of Natural History, “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.”

Sharks currently face a threat today from climate change, as their waters become warmer and fish begin migrating out of the hotter environment. The researchers theorized that a similar change could have caused the extinction of the megalodon.

Pimiento and her team’s experiment helped study the effect of high-level predator removal on an ecosystem, showing that whales began to increase in size only after the 40-foot megalodon had gone extinct.

“We need to find out if one event – Megalodon’s extinction – caused the other – evolution of gigantism in whales,” Pimiento said.

Her findings were published in the journal Plos One.