Researchers have dated vertebrae from a massive prehistoric shark thought to have ruled the waves off northern Australia back to further in the Cretaceous period than was previously known. This shark is now the earliest known mega-predator of the modern shark lineage, living 15 million years earlier than previously found cardabiodontid sharks, the researchers say. The ancestor of today’s great white shark was thought to be about 26 feet long. The study, published in the journal Communications Biology, reveals that these sharks existed 115 million years ago. The discovery sheds fresh light on the evolution process of sharks, according to the study’s authors.