More Terrifying Than a Tyrannosaurs: New Species of Carnivorous Dinosaurs Discovered

What's more terrifying than a tyrannosaurus? That's a good question. Archaeologists have uncovered a new species of carnivorous dinosaur that lived alongside and competed with the comparatively small-bodied tyrannosaurs about 98 million years ago. An apex predator, this new species is one of the three largest dinosaurs discovered in North America.

The new dinosaur is named Siats meekerorum and is a species of carcharodontosaur, a group of giant meat-eaters that includes some of the largest predatory dinosaurs ever discovered. The only other carcharodontosaur known from North America is Acrocanthosaurus, which roamed eastern North America more than 10 million years earlier.

"It's been 63 years since a predator of this size has been named from North America," said Lindsay Zanno, one of the researchers, in a news release. "You can't imagine how thrilled we were to see the bones of this behemoth poking out of the hillside."

The fossil remains are from a dinosaur that would have been more than 30 feet long and weighed at least four tons. Despite this massive size, though, this dinosaur wasn't even fully grown. The Siats remains are from a juvenile, which means that an adult could have reached the size of Acrocanthosaurus. This, in turn, means that the two species could vie for the second largest predator ever discovered in North America. The largest is the Tyrannosaurus rex, which came along about 30 million years later and weighed more than twice that amount.

Siats lived in what is now Utah during the Late Cretaceous period. Acting as the top predator, Siats fills a gap of more than 30 million years in the fossil record. During this time, the role of apex predator changed hands from carcharodontosaurs to tyrannosaurs.

"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 Peter Makovicky, one of the researchers, in a news release. In fact, contemporary tyrannosaurs would have been like jackals in comparison to a lion. It was only after carcharodontosaurs vanished that tyrannosaurs evolved into the terrors that we know.

The findings reveal a little bit more about these dinosaurs. Yet archaeologists are still hunting for further evidence of this dinosaur, which could reveal further insight into this time period.

The findings are published in the journal Nature Communications.