New work led by the Museum shows that giant sharks were hunting in the shallow waters that once covered most of North America for much longer than previously thought.
Researchers from the Dallas Paleontological Society recently discovered a pair of fossil braincases from massive, and now extinct, relatives of modern-day sharks in rocks from Jacksboro, Texas, that date back 300 million years. The researchers, Mark McKinzie and Robert Williams, donated the fossils to the Museum and worked with John Maisey, a curator in the Division of Paleontology, to estimate how big the sharks would have been by comparing them to smaller, more complete fossils of closely related sharks.
The results suggest that these two Texas ‘supersharks’ measured between 18 and 26 feet in length (5.5 to 8 meters). The largest of these specimens would have been 25 percent bigger than today’s largest predatory shark, the great white.
“Everything is bigger in Texas, even 300 million years ago,” Maisey said.
These new fossils indicate that giant sharks go much further back into the fossil record than previously thought. Prior to this find, the oldest giant shark specimens had been recovered from rock dating back just 130 million years. The largest shark that ever lived, C. megalodon is much younger, with an oldest occurrence at about 15 million years ago.
The fossil braincases may belong to an extinct species of shark called Glikmanius occidentalis, or they may represent a larger related species that is new to science.
The researchers presented their findings on the new Texas “supershark” at the 2015 annual meeting for the Society of Vertebrate Paleontology.