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Introducing Raptorex

University of Chicago paleontologist Paul Sereno and five colleagues are introducing Raptorex kriegsteini to scientific literature today with an article in the online edition of the research journal Science. Raptorex is a big surprise to scientists -- a 9-foot-long, 150-pound look-alike of the 43-foot-long, 13,000 pound Tyrannosaurus rex. Tribune photo by Nancy Stone