John Lithgow has revealed he will have to re-record his Good Dinosaur role from scratch.
The 3rd Rock From The Sun star reassured fans that the delayed Pixar film is to undergo a complete overhaul.
"I recorded the entire role in Good Dinosaur. They have now dismantled it and completely re-imagined it, and it is a fantastic new story," he told Collider.
"So I'm gonna record again on it within the next month. Don't worry. It's coming and it's gonna be better than I ever imagined."
He added: "But me and Frannie McDormand, we're still playing Momma and Poppa dinosaur."
The US release of The Good Dinosaur was pushed back from May 30, 2014, to November 25, 2015, when one of the directors, Bob Peterson, left the project. His co-director, Peter Sohn, will now oversee it as part of the Pixar Brain Trust.
John will play Poppa, the patriarch of the Apatosaurus family, with Frances McDormand as his wife Momma.
Bill Hader was cast as elder brother Forrest, with Neil Patrick Harris and Judy Greer as middle siblings Cliff and Ivy, and Lucas Neff as the youngest child Arlo.
The film, which explores the theory of dinosaurs not going extinct, centres on Arlo, a lively 70-foot-tall teenage Apatosaurus with a big heart, who sets out on a quest to restore peace with his new friend - a young human boy named Spot.