With four-foot-long jaws, an ancient reptile terrorized the seas even as Tyrannosaurus rex ruled the land.
The great white shark of “Jaws” fame would probably have been but a tasty morsel for a giant, ancient seagoing lizard recently renamed “Jaws of Death” for its formidable bite.
“If you were an animal in the oceans less than 20 feet in length, you are most likely on the menu for Gnathomortis,” said paleontologist Joshua Lively, who chose the new moniker.
The reptile, whose fossilized remains were discovered in 1975 by a teen who reported the find to his science teacher, had originally been named Prognathodon stadtmani, Utah State University said in a statement. It was known to be a type of mosasaur, a designation that remains.
They lived between 92 million and 66 million years ago, in the twilight years of the Age of Dinosaurs, and trolled an ocean that covered what is today North America from Utah to Missouri, and Texas to the Yukon, USU said. Though air-breathing rather than gilled, these predators “were streamlined swimmers that devoured almost everything in their path, including fish, turtles, clams and even smaller mosasaurs,” USU said.
Enter Lively, who took over recently as the curator of the Prehistoric Museum at USU’s Price Campus. Long fascinated with the fossil, Lively had included it as a chapter in his 2019 doctoral dissertation.
Upon arrival at the institution, he reexamined the fossil, which is displayed at the museum, and found some key differences that set it apart from its original distinction.
“The new name is derived from Greek and Latin words for ‘jaws of death,’ ” Lively said in the university’s statement. “It was inspired by the incredibly large jaws of this specimen, which measure four feet in length.”
For one thing, he found a large depression on the jaws’ outer surface that indicates large jaw muscles were in play, equipping the marine reptile with a formidable bite. Other characteristics indicated that this specimen predated Prognathodon by a few million years, he said.
“We now know Gnathomortis swam in the seas of Colorado between 79 and 81 million years ago, or at least 3.5 million years before any species of Prognathodon,” Lively said.
But even up against those animals, Gnathomortis’s jaw strength stood out.
It crunched turtle and clam shells as if they were popcorn, cannibalized smaller versions of itself, and generally ate anything that came in its path, Lively told Reuters.
As if jaw strength weren’t enough, it also, as is de rigeur for many lizards and snakes, had a second set of teeth on the roof of its mouth.
“In general, mosasaurs actually filled a lot of roles in the oceans over the last 15 million years of the age of dinosaurs,” Lively told Reuters. “Some specialized in eating clams, some were fish specialists, and others were clearly macropredators that could devour anything smaller than them. This mosasaur was one of the latter.”