A Triceratops with a 1,000-pound head and three massive horns, a 15-foot-tall Wooly Mammoth, a 3,000 pound T-rex with a threatening jaw and a 98-foot long Alamosaurus with a 20-foot long tail will be the newest residents at the Philadelphia Zoo. These animatronic dinosaurs will be part of a major new exhibit opening on March 29.