A new species of carnivorous dinosaur that was the apex predator 100 million years ago, predating the Tyrannosaurus rex, was discovered in Utah, making it one of the three largest dinosaurs ever found in North America, scientists announced Friday.
The Siats meekerorum was 30 feet long, weighed at least four tons, and was named after the man-eating monster from Ute tribal legend and the Meeker family, recognized for its support of paleontologists at the Field Museum in Chicago.
Since the bones were from a juvenile, scientists theorize that an adult Siats might have vied with the Acrocanthosarus as the second-largest predator ever discovered in North America behind the T. rex, which came 30 million years later and was twice the weight.
"It's been 63 years since a predator of this size has been named from North America," said Lindsay Zanno, a North Carolina State University paleontologist and lead author to a Nature Communications paper describing the find. "You can't imagine how thrilled we were to see bones of this behemoth poking out of the hillside."
Zanno made the discovery five years ago on a Field Museum expedition led by Peter Makovicky to the 100-million-year-old rocks of the Cedar Mountain Formation. It came just days before the expedition was to end and when morale was low, according to the Chicago Tribune.
Here’s more from Zanno:
"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," said Makovicky, who co-wrote the Nature Communications paper with Zanno about the find.
From the NC State press release:
Siats terrorized what is now Utah during the Late Cretaceous period (100 million years ago to 66 million years ago). It was previously unknown who the top meat-eater was in North America during this period.
"Carcharodontosaurs reigned for much longer in North America than we expected," says Zanno. In fact, Siats fills a gap of more than 30 million years in the fossil record, during which time the top predator role changed hands from carcharodontosaurs in the Early Cretaceous to tyrannosaurs in the Late Cretaceous.
The news about the Siats meekerorum find comes on the heels of an announcement earlier this month about a smaller T. rex ancestor from 80 million years ago, the Lythronax argestes, that had been discovered in southern Utah, proving such predators had been around 10 million years earlier that previously known, according to the Chicago Tribune.
Makovicky also said the team found early tyrannosaurs and several species of other feathered dinosaurs that have yet to be described, including two new species of dinosaurs.
"Stay tuned," Zanno said. "There are a lot more cool critters where Siats came from."
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