This exhibit sketch showcasing an Irish elk, woolly mammoth and other creatures from the Earth’s most recent ice ages is just one possibility of what visitors could see after the museum’s largest, most extensive exhibition renovation is complete. The Nation’s T. rex arrived at the National Museum of Natural History on April 15, and will be the centerpiece of the museum’s new 31,000-square-foot dinosaur and fossil hall, which is slated to open in 2019.