Exquisitely preserved fossils of a shark that thrived during the Cretaceous period appear to solve a long-standing mystery ...

At the start of the Cretaceous Period, which began 145 million years ago, sharks were once again widely common and varied in the ancient seas, before experiencing their fifth mass extinction event.

Long before the carnage began, the Cretaceous picked up where the Jurassic ... snakelike mosasaurs. Rays and modern sharks became common. Sea urchins and sea stars (starfish) thrived; coral ...

Cretoxyrhina was one of the largest sharks and a formidable predator in the Late Cretaceous seas. Nicknamed the Ginsu shark after the kitchen knife that slices and dices, Cretoxyrhina ripped apart ...

TIM: This specimen was collected over 35 years ago, and it's only now that we understand that it represents the first fossil of a Carcharodontosaurus a shark ... lived in the Cretaceous period.