New Genus of Ancient Marine Reptile Uncovered at USU Eastern

A 25-foot leviathan was right under the scientists’ noses but it took several decades for them to realize that it wasn’t what they thought it was.

The aha! moment belongs to Kenneth Carpenter, director and curator of paleontology at Utah State University Eastern Prehistoric Museum, and two of his colleagues, Bruce A. Schumacher and Michael J. Everhart.

For nearly five decades it was a case of mistaken identity for what scientists thought was a Brachauchenius lucasi. But thanks to some skull sleuthing by Carpenter and his colleagues, what they discovered was a whole new genus and species of marine reptile, the Megacephalosaurus eulerti, meaning “Eulert’s great-headed reptile.”

Their find is particularly compelling because it challenges the assertion that only one top predator can exist at a time within an ecosystem. For example, new findings suggest that today’s killer whales, or orcas, may be more than one species. The plausibility of top modern predators coexisting now has some impressive historical precedence.

Carpenter’s ancient monster was the orca of its time that thrived about 91 million years ago. And oh what a noggin!

“It is a huge skull — almost five feet long with big, bone-crushing teeth,” Carpenter said. “There are parts of a second specimen that indicate a skull almost six feet long, so that individual would have been roughly 30 feet.”

That’s twice as big as the formerly mighty B. lucasi — despite both being short-necked plesiosaurs.

Carpenter is coauthor on a new article in the prestigious Journal of Vertebrate Paleontology describing the discovery of this giant, extinct marine reptile from the age of dinosaurs. And though separated by millions of years, having his name now included in the newly named genus, makes it profoundly personal.

“The significance of the article is that for almost 50 years the specimen had the wrong name,” Carpenter said. “That was partly my fault because in 1996 I used the name assigned to it when I described the specimen for the first time in the published part of my dissertation.”

At that time, only the top side of the skull of the marine reptile was visible in its plaster of Paris encasement.

“Originally the entire skull was cleaned and displayed but to make it look pretty, the top of the skull was left exposed and then embedded in plaster to make it look like it was still in the rock,” Carpenter said. “So it was done strictly for esthetic reasons.”

Restoring it to its original state, however, laid the groundwork for an even more beautiful find.

The specimen, which was housed at the Sternberg Museum of Natural History in Kansas, was transported to Carpenter’s lab in Denver five years ago where he completely removed it from its plaster entombment. Once the skull was fully exposed, he and his colleagues were able, for the first time, to clearly peer into the roof of the monster’s mouth. From the depths of the plaster emerged the true breadth of their find: they knew they had stumbled upon something quite different from what they supposed.

For some time they had kicked around the idea of freeing the beast’s massive skull from its plaster prison to allow them a closer look at its other side. What finally convinced them was a photo Everhart found of the skull before it was encased in plaster. To their surprise, instead of seeing a battered underside that is typical of bones when they are excavated, they found the skull to be in pristine condition. It was assurance that their endeavor would be worth the effort.

And it was. Carpenter said the underside of the skull revealed so much new information that he became convinced early on that they were dealing with a new species of reptile altogether. What sealed the deal was a thorough analysis of another B. lucasi skull housed at the Smithsonian that was on loan to them. Careful comparisons revealed that while the tops of both skulls looked similar, the underside of the Smithsonian skull turned out to be significantly different — substantial enough to know they had a new genus on their hands.

The fact that this skull was already well known among scientific circles made it imperative that they stood on solid ground before declaring it a new genus. They knew they were raising the old argument of what constitutes a genus versus a species in the fossil record, Carpenter said.

This find also challenges the line of reasoning that to be king of the hill requires being the only one on top of the hill. History curiously appears to be repeating itself with today’s killer whales, or orcas. DNA work done on these modern day sea hulks reveals that they may be more than one species, yet they are living at the same time — just as B. lucasi and M. eulerti did in ancient times.

“We have shown that you can have more than one top predator at a time; they just specialize in eating different types of foods,” Carpenter said. “In the case of these ancient marine reptiles, the big-headed guy probably ate whatever he wanted and was probably more of a general feeder than the smaller one.”

Exactly where they were feeding now weighs on Carpenter’s mind. His hunch is that he won’t have to look too far. That’s because the waters in which they swam comprised the great Western Interior Seaway. It was a huge inland sea that split through the middle of America, including a large swath of eastern Utah, in its span from the Artic to the Gulf. What is especially exciting to Carpenter is that the smaller related species, B. lucasi, has already been discovered in the Grand Staircase region, “so there is the possibility of finding this bigger guy between Green River and Price,” he said.

Preliminary searches in 2012 failed to yield the monster but on the way other giants were found in the form of four- and five-foot clams wedged between ancient Mancos Shale sea bottom sediments east of Price.

No doubt this dogged paleontologist has picked up a scent that will hopefully yield some startling future finds.

Related links: