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.

Previously, giant sharks had only been recovered from rock dating back 130 million years, during the age of the dinosaurs. The largest shark that ever lived, commonly called "Megalodon", is much younger, with an oldest occurrence at about 15 million years ago. This means the new fossils from Texas indicate giant sharks go much further back into the fossil record.

After the generous donation of these fossils and careful study with Dr. John Maisey of the American Museum of Natural History in New York, the team was able to estimate how big the entire sharks would have been by comparison with smaller and more complete fossils of closely related sharks. The results were very impressive.

The size range estimated for these two Texas 'supersharks' was between 18 and 26 feet in length (5.5 to 8 meters). The largest of these specimens was 25% bigger than today's largest predatory shark, the Great White. Although not nearly as large as Megalodon, which might have reached up to 67 feet in length (about 20 meters), the fossil sharks from Texas would have been by far the biggest sharks in the sea.

These fossil braincases may belong to an extinct species of shark called Glikmanius occidentalis, or they may represent a new and larger related species that is new to science. Closely related sharks are known from as far off as Scotland, showing this group of sharks was capable of dispersing across great distances.

Maisey, McKinzie, and Williams timed their research results very well, being able to present their Texas 'supershark' at the annual meeting for the Society of Vertebrate Paleontology in Dallas, Texas on October 16. According to Maisey, even 300 million years ago, "everything is bigger in Texas!"