A teenage T. rex about to chomp on the triceratops pinned under its foot will be the focal point of the redesigned Fossil Hall when it reopens June 8, 2019, at the Smithsonian’s National Museum of Natural History.

Museum director Kirk Johnson announced the opening date of the David H. Koch Hall of Fossils on Tuesday morning, unveiling a piece of the 66 million-year-old fossil to mark the occasion. Named the Nation’s T. rex, the dinosaur was discovered in Montana in 1988 and is on loan from the U.S. Army Corps of Engineers. It is the first new dinosaur to be added to the hall since 1981.

The Fossil Hall “is the most visited room in the most visited natural history museum in the world,” Johnson said. “It will open in 326 days, not that I’m counting, and between now and then we have dozens of crates to open, hundreds of bones to articulate and many, many exhibits to install.”

The Fossil Hall has been closed since April 2014 for a $125 million renovation that has transformed the 31,000-square-foot space. The project has returned the wing of the museum, first opened in 1910, to its original architectural grandeur, with soaring ceilings, ornate molding and skylights that had been buried for years.

The exhibition will feature 700 specimens of dinosaurs, plants and insects, some that have never been displayed, to tell the story of life on Earth. From the dramatic posture of the 40-foot T. rex to the interactive displays that will engage visitors with scientific learning, the exhibition will be different from any other, Johnson said.

“Our exhibit begins in the past and ends in the future. It is my hope that this exhibit will challenge people to understand and comprehend they are part of the story of our planet,” he said.

On Tuesday, Johnson and dinosaur curator Matthew Carrano unveiled two crates that were shipped from Canada, where the dinosaur had been mounted. One of the most complete T. rex skeletons ever found, the dinosaur has about half of its more than 400 bones, Carrano said, noting the missing pieces have been reconstructed from models. The skull that will be displayed also is a reconstructed model, he said. The original is too fragile to put on view and will live in the museum’s collection space.

The restoration will open on time, which is good news for the museum.  Attendance has dropped since the hall’s closing. Last year the museum reported 6 million visitors — making it one of the most popular in the city — but still well below the 8 million visitors it welcomed in 2013.

David H. Koch gave $35 million in 2012 to launch the fundraising effort, which ended with $81 million in federal funds and $44 million in private donations. The well-known philanthropist is a controversial figure among scientists and environmentalists for his statements about climate change and his support of groups that deny humans’ role in it. His name is on another museum hall, Johnson noted.

“We don’t vet our donors about their politics, and our donors don’t have any influence over our exhibitions,” Johnson said.

The five-year renovation has allowed the curators to reimagine the dinosaur exhibitions and incorporate the newest science and discovery, while also preserving some of its most beloved elements.

When the exhibition closed in 2014, some of the skeletons on view had been in the same position since 1923, Johnson said. “Think of how much science, how much we have learned since then,” he said. “Natural history museums really can change the world, and this one is the biggest one, and we’re going to make a big dent with this exhibit.”