The new exhibition, Last American Dinosaurs: Discovering a Lost World, opens tomorrow, November 25th. Our giant skeletons of Triceratops and Tyrannosaurus rex have been joined by dozens of smaller animal and plant specimens found in rocks of the Hell Creek Formation, which date from the very end of the Cretaceous Period, 66 million years ago. Exhibit labels and graphics have been installed, videos from the field are playing, and several artist's reconstructions of latest Cretaceous animals and their environments are on the walls. This series of photos shows the exhibit coming together over the last couple of weeks. Our Paleobiology and Exhibits staff have been busy!