How Dangerous Was the Tiny T-Rex?

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They call him Raptorex.

He was “mansized”.

He was just as dangerous as one of the big guys.

“...Even at such a diminutive size, Raptorex would have been just as savvy a killing machine as the later T. rex. “I would suspect that the common parrot-beaked dinosaurs (Psittacosaurus) were often dinner,” Sereno said.

Its meat-eating prowess can be attributed to a scaled-down version of just about all of the predatory traits found in T. rex, the researchers say. Specifically, the researchers found that Raptorex was equipped with tiny forelimbs, long legs for quick running, powerful jaw muscles, an oversized head relative to its torso, and enlarged olfactory bulbs suggesting an expert sense of smell — all hallmarks of its overgrown progeny.

“Many of these traits have never been seen in anything but the big brutes,” Sereno said. “That’s what’s so surprising about the whole thing, from tooth to limbs to even the space for the brain, we see things we used to think were just exclusive to the big tyrannosaurids in the late Cretaceous. But there they are.”

From the fossil record, scientists know that other primitive tyrannosaurs with small bodies existed millions of years before T. rex. But their similarities to later tyrannosaurs were often limited, and might include only a similar tooth feature or hip bone, Sereno said.

“There were many intermediate species,” Sereno said. “However, Raptorex is about as close as we may ever come to a direct ancestor of all of the later big guys and gals we call tyrannosaurids, including T. rex.”

Xu Xing of the Institute of Vertebrate Paleontology and Paleoanthropology in China, who was not involved in the discovery, said the finding suggests typical tyrannosaurid features evolved much earlier than previously thought.

“You would not be surprised to see a large tyrannosaurid with a huge skull and tiny forelimbs, but it is amazing that you see these features in a relatively small animal when other similarly-sized, closely related species are more like other theropods in having a smaller skull and larger arms,” Xu told LiveScience….”

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