Prehistoric 91-million-year-old Shark Discovered in Kansas Was Size of a Great White and Had Cannibal Babies

Researchers have identified the remains of an entirely new species of prehistoric shark in Kansas, which lived during the age of the dinosaurs and may have measured around 17 feet in length.

The 91-million-year-old remains were found in 2010 during excavations at a ranch near Tipton in the north of the state, according to a study published in the Journal of Vertebrate Paleontology.

"We were on the site to collect fragments of plesiosaur bones that I had discovered on a previous visit," Mike Everhart, a paleontologist from Fort Hays State University and author of the study, told Newsweek. "One of our party, Fred Smith, had never collected fossils in shale even though he lives about three miles away. He came along because he was curious about what we were doing."

"The fragments we were collecting were small, hard to find and uninteresting to him, so he went exploring a little further up the hillside," Everhart said. "A few minutes later he came back carrying a large concretion that had circular-shaped objects on both ends. He thought it was a fossilized tree limb and didn't believe me at first when I told him they were shark vertebrae. We marked the spot but had to wait several weeks because of the weather to come back and begin collecting the rest of shark remains."

Everhart subsequently contacted Kenshu Shimada—a professor of paleobiology at DePaul University in Chicago and research associate at the Sternberg Museum in Kansas—and this eventually led to larger-scale excavations.

These excavations revealed an incomplete skeleton preserved in sediments once located below an ancient ocean known as the Western Interior Seaway. This body of water divided the continent of North America into two landmasses during the Late Cretaceous Period (144 million to 66 million years ago.)

According to the study, the shark—dubbed Cretodus houghtonorum—was impressively large. The lack of a complete skeleton makes it hard to come up with a definitive figure, but according to the researchers' estimates, this specimen measured around 17 feet. That makes it about the same size as modern great white sharks, although probably more sluggish.

Furthermore, a growth model for the shark showed that, in theory, it could have increased to a staggering 22 feet in length.

In total, the team discovered 134 teeth, 61 vertebrae, 23 scales and several fragments of calcified cartilage. While incomplete, these remains represent the best specimen of the genus (group of species) Cretodus found in North America, the authors of the study say.

"Sharks have a cartilaginous skeleton, so much of the biology of extinct sharks relies on inferences from isolated teeth that have a better fossilization potential," Shimada told Newsweek. "This new fossil find is significant because the specimen represents a partial skeleton of an individual shark where we were even able to reconstruct its dental pattern in its mouth. The specimen not only offered a wealth of new biological information about the shark, but also led us to the realization that it belongs to a species new to science."

"As important ecological components in marine ecosystems, understanding about sharks in the past and present is critical to evaluate the roles they have played in their environments and biodiversity through time, and more importantly how they may affect the future marine ecosystem if they become extinct," he said in a statement.

prehistoric shark
One of over 100 associated teeth of the newly described, 91-million-year-old fossil shark from Kansas, Cretodus houghtonorum. DePaul University

The newly identified species was named in honor of Keith and Deborah Houghton, who owned the land where the remains were found and subsequently donated them to scientists. Cretodus houghtonorum belongs to an order of sharks known as Lamniformes, which includes great white sharks, sand tiger sharks, and many other well-known species.

Intriguingly, the inferred size of the new shark at birth—almost 4 feet in length—suggests that its embryos engaged in behavior known as intrauterine cannibalization, which is seen in many modern Lamniform species.

"Lamniform sharks don't lay their eggs outside of the body, but instead eggs hatch inside the mother, where the mother will then give live birth to young pups," Shimada said. "A very interesting fact is that 'early-hatched' embryos will begin to eat surrounding unhatched eggs and, at least in some species, occasionally even other hatched siblings for nourishment."

"The consequence is that only a few pups will survive and develop, but each of those pups can become considerably large in body size at birth, which in turn gives neonates an advantage as 'already-large' predators with reduced chances of getting eaten by other predators," he said. "It's wild to consider that natural selection is already at work for these embryos inside their mothers even before they actually venture into the ocean."

The findings suggest that this unusual behavior must have already evolved by the Late Cretaceous Period.

Another interesting aspect of the discovery is that the Cretodus houghtonorum remains were found among those of two other sharks, representing the groups Squalicorax and hybodont.

"Circumstantially, we think the shark possibly fed on the much smaller hybodont and was in turn scavenged by Squalicorax after its death," Everhart said in a statement.

When the researchers came across the Cretodus houghtonorum remains, they initially thought that they represented another species in the same genus known as Cretodus crassidens, which was first reported in England and subsequently across North America. However, further inspection revealed that the teeth did not match those of Cretodus crassidens, casting doubt on other findings of the shark in North America.

"That's when we realized that almost all the teeth from North America previously reported as Cretodus crassidens belong to a different species new to science," Shimada said.

Prehistoric 91-million-year-old Shark Discovered in Kansas Was Size of a Great White and Had Cannibal Babies | Tech & Science