300 million-year-old 'supershark' fossils found in Texas

Massive extinct relatives of modern-day sharks were roaming Texas 300 million years ago, even before the age of dinosaurs, a new study has found.
During a time called the Carboniferous, some 300 million years ago, the area surrounding what is now Dallas in Texas was flooded by a shallow sea.
Fossils from this ancient environment have been recently recovered from Texas. 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.

The new fossils from Texas indicate giant sharks go much further back into the fossil record, researchers said.

After a careful study of these fossils, researchers from the Dallas Paleontological Society and American Museum of Natural History were able to estimate how big the entire sharks would have been by comparison with smaller and more complete fossils of closely related sharks.
The size range estimated for these two Texas 'supersharks' was between 18 and 26 feet in length.
The largest of these specimens was 25 per cent 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, 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.
The study was published in the Journal of Vertebrate Paleontology.