Even before the age of dinosaurs, big toothy predators were roaming Texas. 300 million years ago, during a time called the Carboniferous, the area surrounding what is now Dallas, Texas was flooded by a shallow sea. Fossils from this ancient environment were recently recovered from Jacksboro, Texas by Mark McKinzie and Robert Williams of the Dallas Paleontological Society. Among these were two fossil braincases from massive extinct relatives of modern-day sharks.