The Field Museum reports that researchers from the museum, the North Carolina Museum of Natural Sciences (NCMNS) and North Carolina State University (NCSU) have discovered a new dinosaur that likely made even tyrannosaurs cower in fear. According to the museum, the top predator walked the Earth approximately 100 million years ago, in Utah’s Cedar Mountain Formation. The discovery, which is detailed in the journal Nature Communications, is the first of its kind in North America.

More than 30 feet long and weighing over four tons, the dinosaur known as Siats meekerorum, a reference to a cannibalistic monster from the mythology of the Ute Native American people, terrorized other creatures that roamed the Earth during its reign.

“This dinosaur was a colossal predator second only to the great T. rex and perhaps Acrocanthosarus in the North American fossil record,” remarked Lindsay Zanno, lead author on the paper and Director of Paleontology at NCMNS/NCSU, in a news release.

“It’s been 63 years since a predator of this size has been named from North America. You can’t imagine how thrilled we were to see the bones of this behemoth poking out of the hillside.”

The deadly animal was discovered back in 2008 by Zanno during an expedition to the Cedar Mountain Formation. After two summer of back-breaking work, Zanno and her crew painstakingly removed the fossils of this humongous creature.

Siats is not a close relative of  T. rex and the other tyrannosaurs that were the top predators in North America for the last 20 million years of the age of dinosaurs. In fact, Siats belongs to the carchardontosaurian group of theropods. More specifically, the monstrous animal belongs to a branch of the carcharodontosaurian family tree that was previously unknown in North America.

“We were thrilled to discover the first dinosaur of its kind in North America and add to mounting evidence that dinosaurs were widely dispersed across the globe 100 million years ago,” noted Peter Makovicky, Curator of Dinosaurs at the Field Museum.

According to the researchers, the teeth of tyrannosaurs from the area imply that the tyrannosaurs residing alongside the top predator were not as big as their four-ton friends.

“The huge size difference certainly suggests that tyrannosaurs were held in check by carcharodontosaurs, and only evolved into enormous apex predators after the carcharodontosaurs disappeared,” said Makovicky.

“Contemporary tyrannosaurs would have been no more than a nuisance to Siats, like jackals at a lion kill. It wasn’t until carcharodontosaurs bowed out that the stage could be set for the evolution of T. rex,” noted Zanno.

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