The age of the dinosaurs has come to an end, while the dawn of mammals has just begun. After gracing the grand entrance hall of the Natural History Museum London for almost four decades, the much beloved Dippy the Dinosaur has given way to an equally impressive beast, as Hope the Blue Whale now takes center stage.

Positioned as if taking a lunging dive straight through the Hintz Hall, the whale measures an impressive 25.2 meters (83 feet) long, giving visitors a chance to walk underneath the largest animal that has ever lived. The installation of Hope within the entrance hall marks a change of image for the museum, which wants to be seen as a place where cutting-edge science occurs, working to document and save living creatures, and not just a storage place for old fossils.

“Putting our blue whale, Hope, at the centre of the Museum, between living species on the West and extinct species on the East, is a powerful reminder of the fragility of life and the responsibility we have towards our planet,” explained Sir Michael Dixon, Director of the Natural History Museum. “We are living at a critical point in the history of the Earth. This generation’s decisions will have an unprecedented impact on the world we live in.”

The whale’s origins are actually Irish; the 25-meter female was washed up on the southeast coast of Ireland in 1891. While the museum obviously uses their wealth of dinosaur fossils for research, they want to focus attention on the ongoing work that they do with living species in order to better understand and save them, and by hanging Hope in such a prominent place, they aim to send a profound message to all who will see her.

Once numbering at around 250,000, by the 1960s there were only thought to be around 400 blue whales left in the world. Due to science and conservation, some of which was carried out at the museum itself, the world agreed in London in 1966 to stop all hunting of the magnificent animals, marking the first time humans decided to save a single species on a global scale. Now their numbers have grown to around 20,000, and have started to form viable populations.

The incredible skeleton – constructed from of 221 bones – has replaced the ever popular Diplodocus known affectionately as “Dippy”, who had been greeting visitors as they entered the building through the main doors since 1979. But the fact that Dippy gives us a glimpse back on life on Earth, and that the fossil is really a cast made of the real bones in 1905, meant that the museum thought that his time had been and gone, for the time being at least. He is set to go on a UK tour in early 2018.