Dinosaur Discovery: Was there a Predator Bigger and Scarier Than the T-Rex?

Scientists have discovered a new gigantic carnivorous dinosaur that predates and even trumped the Tyrannosaurus for millions of years.

According to a press release, the dinosaur, named Siats meekerorum, is one of the three oldest species to ever walk the Earth in North America. The dinosaur lived 98 million years ago and was the top predator of its time.

Its given species name, "Siats," comes from an Ute tribal legend of a giant cannibalistic man-eating monster. It comes from a family of dinosaurs called carcharodontosaur and Siats is not the first to be discovered in North America. The first is called the Acrocanthosaurus, which existed ten million years earlier than Siats, and it was discovered in 1950.

"It's been 63 years since a predator of this size has been named from North America," study lead author Lindsay Zanno, a North Carolina State University paleontologist with a joint appointment at the North Carolina Museum of Natural Sciences. "You can't imagine how thrilled we were to see the bones of this behemoth poking out of the hillside."

Zanno and her team of scientists published their work in the journal Nature Communications. Peter Makovicky, from Chicago's Field Museum of Natural History, and Zanno discovered the Siats specimen in 2008 in Utah's Cedar Mountain Formation. The skeletal specimen would have been 30 feet long and weighed four tons, but it was a juvenile at the time of its death.

Siat is part of a subgroup of the carcharodontosaur called Neovenatoridae, which were more slender and found previously in Europe, South America, China, Japan, Australia and, for the first time, North America.

"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.

The researchers agreed that the T. rex only rose to prominence when the larger, possibly more ferocious Siats died out.

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