An ancient shark species once swam in the rivers of present-day South Dakota, researchers reported yesterday (January 21) in the Journal of Paleontology. The fossils came from the Hell Creek Formation ...

That would make T. rex the hardest-biting terrestrial animal ever known. (C. megalodon, an extinct giant shark, bit at an estimated 41,000 pounds; Deinosuchus, an ancient crocodilian, at about ...