Megalodon sharks went extinct 2.6 million years ago, allowing whales to grow in size, eventually becoming the largest animals on the planet.
University of Florida (UF) researchers, along with scientists from the University of Zurich, examined records of fossils finds to develop the theory. Researchers believe this study may help biologists learn more about the effects on local environments of the removal of top-level predators. Many shark species are beginning to disappear worldwide as part of a global drop of biodiversity.
"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," Catalina Pimiento, a doctoral student at the Florida Museum of Natural History and lead author of the study, said.
Large filter-feeder whales evolved around the same time as the giant shark went extinct, pointing to the possibility that decline of megalodon may have led, in part, to the rise of giant whales.
Rumors that Megalodon still exists in the oceans have gained traction in recent months, as stories of the animals propagate on the internet. The Discovery Channel also recently aired television specials that suggested the animal might still be alive in remote areas of the global ocean.
"I was drawn to the study of Carcharocles megalodon's extinction because it is fundamental to know when species became extinct to then begin to understand the causes and consequences of such an event," Pimiento said.
This genetic analysis represents the first step of an in-depth investigation Pimento is carrying out surrounding the extinction of Megalodon. As part of that research, she will carefully study how the distribution of the species may have affected popululations of other marine vertebrates, including large whales.
Databases detailing megalodon finds from around the world were examined by the researchers, in an effort to develop a means of dating the extinction of the species. The team believes their research will not only put an end to rumors the animal is still extant, but that their techniques will also be used by other researchers to study other extinct plants and animals.
"The methodology that the authors used had only been previously employed to determine extinction dates in historical times, such as to estimate the extinction date of the dodo bird. In this work, scientists applied that same methodology to determine the extinction of an organism millions of years ago, instead of hundreds. It's a new tool that paleo biologists didn't have, or rather had not thought of using before." Jorge Velez-Juarbe of the Natural History Museum of Los Angeles County, told the press.
Genetic analysis of megalodon and what the study could tell us about their extinction was profiled in the online journal Plos One.
