The Good Dinosaur - Reasons for the Delay
Pixar's newest film The Good Dinosaur was supposed to hit cinemas in summer 2014 but was then postponed by more than a year. The main reason for that was a changed in the director's chair. Bob Peterson was replaced by Peter Sohn and a clearer explanation for that is available now, too. Peterson had problems to get the story working in a way that satisfied Pixar's standards. When Sohn took over, some important story elements were subsequently changed, as well.
The main plot framework stayed and says that there was no asteroid that hit Earth 65 million years ago and thus there was no apocalypse that wiped the dinosaurs off the face of the planet. Instead, they continued to be the dominant species even when the first humans surfaced. Arlo, the hero of the story then befriends a young human called Spot and keeps him as a pet.
Among the changes is that the dinosaur society isn't modeled according to the life of the Amish community and that their farming lifestyle and thus their closeness to nature aren't elementary parts of the plot any longer. Instead, nature is now the antagonist.