Watch: Colin Trevorrow reveals joy of designing feathered dinosaurs
Creatures including the feathered therizinosaurus and pyroraptor are unveiled in Dominion — in IMAX and cinemas from 10 June — alongside favourites like velociraptors and T-rex — as well as the enormous predator giganotosaurus.
"[The feathered dinosaurs] were almost like the dinosaur version of the legacy characters that I had been holding on to," Trevorrow told Yahoo Entertainment UK.
He added: "When you make a third film, you really want to give people a reason to come back to see the conclusion of the story you're telling.
"So a lot was kept in the tank. I had a lot of ammo."
Trevorrow's trilogy — he directed Jurassic World and Dominion, while co-writing middle entry Fallen Kingdom — has yielded an array of new dinosaurs, but the director counts the feathered ones among his favourites.
"In this movie, I love the therizinosaurus. It looks incredible and it feels like a real thing," he said.
Dominion reunites characters old and new as it tells the ambitious story of a world in which dinosaurs and humans are forced to co-exist.
The director added: "We're defining how a feathered dinosaur looks in cinema. We've never really seen it before.
"That, to me, was a great honour — to be able to design from the ground up as opposed to a new version of something we already know."
Trevorrow re-entered the Jurassic fold as director for Dominion after he left the director's chair of the movie that eventually became Star Wars: The Rise of Skywalker.
"In some ways, I felt like I was coming out of getting a Masters degree in telling stories based on things that we love from our childhood. It was such an educational opportunity," he said.
"I try to find ways that I can learn from everything. So I come to this and then really have a very similar kind of job: let us wrap up six movies and three movies at the same time and do it in a way that's really satisfying and that respects all of the characters we love without ignoring the new characters that we've created and creating new characters who can take us into the future.
"It was a tall order, but with [co-writer] Emily Carmichael's help and what [Jurassic World co-writer Derek Connolly] and I had built, I'm really proud of what we did."
As for the future, things are uncertain. Dominion is being sold as the conclusion of this particular trilogy of Jurassic films and Trevorrow doesn't think it's likely that he'll be at the helm when the inevitable next time comes around.
He said: "I would love to be involved in providing someone else the kind of mentorship and support that I was given when I came into the franchise.
"I think that to say there will never be any more Jurassic stories would be to ignore the fact that a new dinosaur fan is born every day.
"It is certainly the responsibility of this franchise to make sure kids keep having dinosaurs in movie theatres."
But for now, Trevorrow simply hopes that the work he and his team have done on Dominion is enough to satisfy the fans of the Jurassic franchise, young and old.
"I'm just laying this movie at the feet of the audience and you hope that they will enjoy this meal that we've cooked for them," said Trevorrow.
He added: "That is always, in a lot of ways, the most unsure moment. When we're making the film, you're just constantly making choices towards a clear goal. And now, we're just like: What do you think?"
Jurassic World Dominion lands in IMAX and UK cinemas on 10 June.
Watch: Trailer for Jurassic World Dominion