Scientists have discovered a two-legged killer dinosaur that roamed in what is now Utah 100 million years ago. The “top predator” was a significant precursor to Tyrannosaurus rex and an important part of the emerging fossil record for the continent, said researchers with the Field Museum of Chicago and the North Carolina Museum of Natural Sciences. The species — Siats meekerorum — was related to allosauroids, not the tyrannosauroid family that included the famous beast. Siats’ best-known relative might be the Giganotosaurus of South America. Because of its size and the history of top predators, scientists theorize that Siats was atop a food chain that included what they called “small-bodied tyrannosauroids,” T. rex’s ancestors, which hadn’t evolved to the size and dominance they would reach before dinosaurs went extinct 65 million years ago.

what’s in a name

Siats meekerorum, (SEE’-otts MEE-ke-ROH’-ruhm) was named after a man-eating monster of legend from Utah’s Ute tribe and the Meekers, a family that has donated to the Field Museum. It follows the announcement earlier this month about the discovery of Lythronax argestes — “the king of gore,” a smaller T. rex ancestor from 80 million years ago.

how big was it?

The 4-ton, 30-foot animal is the third-largest carnivore found on the continent. It would have been “the top dog in his neighborhood,” said museum curator Peter Makovicky. The fossils recovered were from a juvenile; the adult size was estimated based on the recovered fossils, which included bones of the back, tail, hip, foot and shin. Its importance

It represents a whole new group of dinosaurs in North America, filling a gap in the fossil record of big predators between earlier killer beasts and the arrival of the T. rex. family. news services