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Newly-discovered dinosaur kept T-rex down for millions of years

You may think you're looking at a T. rex there, but what you're really seeing is an artist's rendering of a newly-discovered species called Siats meekerorum, a massive apex predator dino that lived millions of years before T. rex showed up, and who was likely the one that kept tyrannosaurs from realizing their true potential for millions of years.

We're all familiar with Tyrannosaurus rex. As the largest predator to ever roam North America, it was essentially the top of the food chain 65 million years ago. Paleontologists have also found another of these 'apex predators', called Acrocanthosaurus, who was second in size to T. rex, and died off around 50 million years before T. rex had its day. Given how these ancient ecosystems worked, something would have grown up to fill Acrocanthosaurus' place, but so far nothing had been found to fill the gap.

Lindsay Zanno, a paleontologist from North Carolina State University, and Peter Makovicky, from Chicago’s Field Museum of Natural History, took up the hunt, focusing their search on layers of rock that were dated at being around 98 million years old. In 2008, while searching Utah's Cedar Mountain Formation, they hit paydirt — finding the fossilized bones of a dinosaur that would have been a juvenile, but still measured 10 metres long and would have tipped the scales at around 4 metric tons.

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

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This newly-discovered species is only the second species of carcharodontosaurus found in North America, after Acrocanthosaurus, and it extends the 'reign' of carcharodontosaurs by roughly 30 million years. Also, given Siats' size, it may end up pushing Acrocanthosaurus down to third place on the list of largest predators that ever existed on this continent. As for tyrannosaurs, at the time that Siats lived, the early ancestors of T. rex were only the size of modern dogs and would have only gotten underfoot, likely picking off of the kills that Siats made.

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

This amazing discovery, published today in Nature Communications, isn't the only one for Zanno and Makovicky. They have apparently discovered two other new dinosaur species, which will be detailed soon.

(Image courtesy: Jorge Gonzales/North Carolina State University)

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