Neal Scanlan, the head of the Creature Workshop for Star Wars, has revealed several key details about some of the new species found in The Last Jedi.
In an interview with Empire, Scanlan explains that Porgs — the race of bird-like creatures that has already sparked a merchandising sensation — are said to be at least partially related to the nun-like Caretakers seen to be living on the island of Ahch-To with Luke Skywalker.
Scanlan felt that when it came to Ahch-To, the "only creatures that would ever exist on this island were those indigenous to it, where very few other species and DNA would have reached them." Instead of a world with diverse populations, as seen elsewhere in the Star Wars Universe, we will see hints of evolution. "[The Caretakers] are an extrapolation from the Porgs and have bird-like feet, but they’re a further developed race."
As for the specific Porg seen in the cockpit of the Millennium Falcon in the film's trailer, Scanlan says, "That porg in particular shows some very Wookiee traits in the way he’s coloured; his patterning is very similar to Chewie’s.” In other words, Chewbacca has a new buddy.
As for the mysterious Crystalline Foxes, Scanlan said, "The theory is they’ve fed off this planet for so long that their fur has become crystalline. They’ve taken on the very surface of the planet they live on.” It has already been mentioned that these creatures will be found on the mineral world of Crait.
Arriving Dec. 15, director Rian Johnson’s Star Wars: The Last Jedi stars Mark Hamill as Luke Skywalker, Carrie Fisher as General Leia Organa, Adam Driver as Kylo Ren, Daisy Ridley as Rey, John Boyega as Finn, Oscar Isaac as Poe Dameron, Lupita Nyong’o as Maz Kanata, Domhnall Gleeson as General Armitage Hux, Anthony Daniels as C-3PO, Gwendoline Christie as Captain Phasma and Andy Serkis as Supreme Leader Snoke.