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Blueprint for a predator

The Raptorex kriegsteini is a 9-foot-long, 150-pound look-alike of the 43-foot-long, 13,000 pound Tyrannosaurus rex. University of Chicago paleontologist Paul Sereno calls Raptorex a "blueprint for a predator," sporting a huge head measuring 40 percent of its body length, powerful jaws, outsized olfactory organs for acute sense of smell, tiny forelimbs, and horse-like rear legs to swiftly run down prey. Tribune photo by Nancy Stone