BILLINGS - The Western Interior Seaway occurred about 70-to-80 million years ago, ran through Billings, and was home to several different species of sharks as well as other marine life.
The Rimrocks of Billings are what's known as Eagle Sandstone, and they once formed a barrier island between a coastal lagoon and the seaway. Millions of years ago it would've resembled a beach.
Kallie Moore — the collections manager at the University of Montana Paleontology Center — says that while the area would've been vastly different, some of the animals would've resembled what we see today.
"The animals would look similar, but you would think they’re in the wrong place. You would be like wait; these are animals that live near the tropics today. Yet, they're living right up here in Montana," Moore said.
The sea was about 3,000 feet deep at the deepest, which is shallow by some standards but was full of large sharks and other predators like Mosasaurs and various boney fish.
Mosasaur, which was a swimming reptile, was the ultimate apex predator in the region and grew to a whopping 52 feet long.
Fossil records show that were more than 20 species of shark that swam in the Western Interior Seaway.
There was also a giant shark that wasn't nearly as big as Mosasaur, but it was an apex predator in its own right.
"Cretoxyrhina is definitely the closest that Montana comes to a great white shark that lived around here and at least one has been found in the general vicinity of Lewistown and Billings," added Moore.
Cretoxyrhina grew up to 26 feet long, had blade-like teeth and many of its teeth have been found embedded in the fossils of Mosasaurs, showing that they were voracious predators and scavengers.
Another was Squalicorax, which was smaller than Cretoxyrhina, generally measuring up to 6½ feet long.
Its teeth marks have been found in various dinosaurs showing that it scavenged on the animals that washed out to sea.
"There's also been teeth marks that have been found in Pterosaur bones, showing it snatched them out of the air," said Moore.
These sharks were top predators and hunters but they didn't have trouble finding food.
"We think that a lot of these sharks were more scavengers. There was lots of organic material back then and there was luckily enough dead stuff around that they just had to focus on being scavengers instead of predators. Although, I guarantee they could’ve caught anything they wanted," added Moore.