Prehistoric Shark That Could Reach 22 Feet and Ate Its Siblings in the Womb Discovered in Kansas

A huge new species of prehistoric shark has been discovered in Kansas, with scientists reporting how the predator could have grown over 22 feet in length and that its young would cannibalize their siblings while still in the womb.

Kenshu Shimada, from Chicago's DePaul University, and Michael J. Everhart, from Fort Hays State University in Kansas, identified the new species from 134 teeth, 61 vertebrae, scales and calcified cartilage found in rocks in the Carlile Formation. The remains date to the Late Cretaceous period, between 66 and 100 million years ago. At this time, North America was split in two by an ancient waterway, known as the Western Interior Seaway.

The species belongs to the genus Cretodus, of which there were four known species. The newly discovered predator has been named C. houghtonorum and details of its discovery were published in the Journal of Vertebrate Paleontology in November.

"This new shark differs from all other known species in the genus by having a distinct array of teeth that are uniquely shaped," Everhart said in a statement. "Our analysis showed that the teeth of this shark are measurably different (size and shape) from any other known species of Cretodus and that justified the naming of the new species."

C. houghtonorum was a large species, Shimada and Everhart say, with the individual found estimated to be almost 17-foot long. However, their analysis also showed the species likely grew up to 22.4 feet. Their specimen died when it was about 22 years old, but they believe the species could live to 51.

The scientists said newborn sharks belonging to this species would be about 3.8 feet, and that this "large size at birth" suggests that—like many shark species living today—embryos would cannibalize their siblings while in the womb. This, the researchers say, shows the behavior had evolved by the Late Cretaceous.

The C. houghtonorum fossils were found near the dorsal fins of a hybodont, as well as the teeth of squalicorax. Both of these were smaller species of shark, with the latter reaching about 6.5 feet in length on average. Based on the condition of these remains, Shimada and Everhart suggest that C. houghtonorum died shortly after eating the hybodont, and then the squalicorax came along and ate the larger shark's carcass.

Shimada and Everhart also note how C. houghtonorum would likely have lived alongside Cretoxyrhina mantelli, one of the largest sharks of the Late Cretaceous. This species could grow over 24 feet in length and would have been an apex predator of the time.

Shimada and Everhart believe the two species would have been able to live together by utilizing different environments—C. houghtonorum near the coast, and C. mantelli in deeper, offshore waters "possibly representing a case of resource partitioning between the two species," the researchers concluded.

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Representative image of a shark. The prehistoric shark found in Kansas could reach up to 22 feet in length, scientists say. iStock