New Delhi, Dec. 14 -- In the age of dinosaurs - before whales, great whites or the bus-sized megalodon - a monstrous shark prowled the waters off what's now northern Australia, among the sea monsters of the Cretaceous period.

Researchers studying huge vertebrae discovered on a beach near the city of Darwin say the creature is now the earliest known mega-predator of the modern shark lineage, living 15 million years earlier than enormous sharks found before.

And it was huge. The ancestor of today's 6-meter (20-foot) great white shark was thought to be about 8 meters (26 feet) long, the authors of a paper published in the journal Communications Biology said.

"Cardabiodontids were ancient, mega-predatory sharks that are very, very common f...