New dinosaur species joins ranks of giant carnivores

An artist's impression of Siats shows the predator terrorizing smaller tyrannosaurs during the Late Cretaceous period.

Julio Lacerda

Recently unearthed fossils reveal a new species of gigantic, meat-eating dinosaur that’s a contender for North America’s second largest predator.

The newly named Siats meekerorum probably roamed what is now Utah about 98 million years ago, terrorizing the ancestors of Tyrannosaurus rex. The fossil bones of S. meekerorum were from a juvenile that was 9 meters long and weighed a little over 3.5 metric tons, scientists report November 22 in Nature Communications.

Adult S. meekerorum might have been similar in size to another predatory dinosaur, Acrocanthosaurus, which is thought to have been 12 meters long and weigh about 6.2 metric tons. The two species now compete for the title of second largest predator found in North America. T. rex, who came along 30 million years later, holds the top spot.

Siats probably lived during the Late Cretaceous period, about 100 million to 66 million years ago, and was the top predator of the time, keeping smaller tyrannosaurs from climbing to top of the food chain until later, the scientists say.

Ashley Yeager is the associate news editor at Science News. She has worked at The Scientist, the Simons Foundation, Duke University and the W.M. Keck Observatory, and was the web producer for Science News from 2013 to 2015. She has a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT.

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