Tyrannosaurus rex—otherwise known as “T. rex”—is unquestionably the superstar of genus Tyrannosaurus, which actually came in many sizes and shapes. Before evolving into predacious terrors, tyrannosaurs were small carnivores. This exhibition tells their story of aggrandizement. “Scotty”—one of the largest and most complete T. rex skeletons in the world—will be on view, ready for his close-up. —E.C.