America loves a good shark story. The country’s obsession with the frightening fish has been manifested by its love of Jaws, Shark Week, and four full-length Sharknado films. Little do Utahns know, the state has its own shark story–kind of. Hundreds of millions of years ago, Northern Utah was at the bottom of a prehistoric sea, which housed large, shark-like creatures with sets of teeth like buzzsaws.
This creature is called a helicoprion, and visitors to the BYU Museum of Paleontology will be able to witness, up close, what made the prehistoric fish so unique: its teeth. The museum recently received a donation of a 270 million-year-old fossil of a helicoprion jaw, featuring what’s left of its pearly whites.
What is a helicoprion?
Before there is any misunderstanding, although a helicoprion closely resembles a shark, it’s not actually a shark. It’s also not a dinosaur.
“It’s a fish,” said museum curator Rod Scheetz. “People kind of tend to lump in anything that lived a long time ago as a dinosaur.”
The ancestors of sharks and helicoprions split into two separate sub-classes 400 million years ago. The helicoprion’s closest living relative is a chimaera—a 4 to 5-foot-long fish with a cartilage skeleton that tends to hang out in deep waters. Chimaeras lack teeth and instead possess several sets of grinding tooth plates, which lack the means to cut and slice when biting down.
Helicoprions are estimated to be much larger than chimaeras and quite different in nature. The helicoprion that owned the jaw in BYU’s museum was probably about 20 feet long. The whorl of teeth in its mouth was used to cut through boneless fish like squids and sharks.
“The smallest, measurable teeth are 5 millimeters long,” Scheetz said. “The largest teeth, which are the newest teeth, are about 55 millimeters long.”
As the fish’s jaw grew, its number of teeth increased. Smaller teeth were pushed forward and downward, creating a swirling spiral of intimidating chompers.
“The newest teeth are pointed down its throat,” said Scheetz. “So any prey that it catches, it’s locked in.”
Life was good for the “buzzsaw killer,” but at some point the fun had to end. Around 245 million years ago, they disappeared. They vanished during the end of the Permian Period on the geologic timescale, hundreds of millions of years before tyrannosaurus rex and triceratops were the big dinos on campus.
Unfortunately, mysteries still surround the helicoprion. Because its body comprised cartilage and not bone, very little has been left behind after 245 million years.
However, some fossils remain, and BYU is fortunate to have come into possession of such a fantastic petrification.
“These [fossils] are rare,” said Scheetz. “This is especially rare.”
Besides having an impression of the teeth, the fossil also contains some calcified cartilage. These small dots located around the teeth allows geologists to re-imagine the structure of the fish’s entire jaw.
“Sometimes we just get the teeth without the calcified part of it,” Scheetz said. “It’s a great specimen.”
Where did it come from?
The fossil was graciously donated to the museum by BYU alums Verl and Irene Mumsford shortly after Verl passed away.
“It was written up in their family trust that when he passed away, [the fossil] was to be donated to BYU,” said Mumsford family friend Marilyn Manwaring. “They were a cute, faithful couple that served anyone around them.”
Verl worked as an accountant at a phosphate plant in Vernal, Utah, and received the fossil as a retirement gift from the plant.
Companies like the one Verl worked at are located throughout Northern Utah and the states above it.
“The Phosphoria Formation is a big oblong geographic area within Northern Utah, Idaho, into Wyoming and up into Montana,” Scheetz said.
Much of the Phosphoria Formation was submerged underwater during the reign of the helicoprion, which is why a handful of helicoprion fossils have been discovered in the area as miners have dug into the phosphate rocks throughout the years.
How do I see it?
Admission to the BYU Museum of Paleontology is free and the fossil is on display now.
“It’s a rare fossil and they’re not in every museum that you go by,” said Scheetz. “It’s a really strange animal.”
For more information, go to geology.byu.edu/museum.