To Move Past Hand-Waving Theories, Scientists Disarm Sue the T. rex

Bill Simpson, Collections Manager of Fossil Vertebrates, carefully disassembles Sue's arms during a public event Friday. (Credit: Hannah Gavin) Sue, the iconic Tyrannosaurus rex fossil housed at Chicago’s Field Museum, measures 13 feet tall from the ground to the top of her hip — a grown man balancing on another man’s shoulders, arms fully outstretched, would barely reach the top. But in terms of reach, an average human arm just about matches the length of Sue’s. Relative to her colossal body, that makes Sue’s arms small – puzzlingly small. So small that the dinosaur couldn’t scratch her own face, says Bill Simpson, a collections manager at Chicago’s Field Museum. If not chin scratching, what purpose did the disproportionately small forelimbs serve? This remains one of the biggest mysteries in T. rex studies to date. In an attempt to solve it, scientists disarmed the remains of the most ferocious creature to walk the earth.