I think that Apatosaurus will be the main non-human protagonist, and a large theropod like T.rex, Giganotosaurus, or Carcharodontosaurus might serve as the primary antagonist.
UPDATE: Since the D23 Expo, more information about the film has been revealed.
- The creators of the movie said they've picked five species of herbivore to be not only farmers, but also function as their own machinery.
- The dinosaurs are: Apatosaurus (plowers), Stegosaurus (threshers), Triceratops (bulldozers), Ankylosaurus (truckers), and Parasaurolophus (pickers).
- The main protagonist is an Apatosaurus named Arlo.
- Director Bob Peterson was asked "What happened to the carnivores?" His reply was that people will have to see the film and find out.
- I'm guessing that, like the herbivores, the carnivores have formed an agricultural society, but they raise livestock instead of growing crops. The likely species and the jobs that they have are: Tyrannosaurus (ranch bosses), Allosaurus (livestock herders), Velociraptor (herding dogs), Deinonychus (butchers), and Spinosaurus (keeping rustlers away).
- They might be the antagonists.
- Concept art in the promotional video for Up show Deinosuchus, Pteranodon, and possibly Microraptor.
UPDATE: Since Peter Sohn became director, the idea of farmer dinos was cut, and nature itself has become the antagonist of the film, so Alro and Spot might run into a few predators on their journey. The other kinds of herbivores from the original concept will likely appear as well.
UPDATE: The following creatures have been confirmed so far:
- Apatosaurus(Arlo and his family)
- T. rex (Nash, Ramsey, and Butch)
- Nyctosaurus (Thunderclap)
- Velociraptor (Bubbha and his pack)
- Styracosaurus (Forrest Woodbush)
- Triceratops (Sam* and Will*)
- Stegosaurus (Mary Alice*)
- Ankylosaurus (Jack* and Vivian*)
- Parasaurolophus (as seen in the teaser)
- Caulkicephalus (Downpour)
- Guidraco (Windgust)
- Ludodactylus (Coldfront and Frostbite)
- The teaser also has a shot of a rex walking among a herd of ancient bison. This indicates we may see some mammals from the Pleistocene in this movie, such as mammoths and saber-toothed cats.
- Now that we have a full-length trailer, more creatures have been shown, including a ceratopsian with small animals living on his frill. His name is Forrest Woodbush. He believes that each animal gives him a special power.
- We also see animals that look very different from their modern versions. One is a snake with short legs, and another is an armadillo-like critter with bumps on its back. This proves that in this alternate timeline, the course of evolution has changed how animals from our time have adapted to living in a world where non-avian dinosaurs didn't become extinct.
- Footage from the 2015 D23 Expo shows that my thoughts about theropods raising livestock is true. Butch and his kids raise long-horned bison. They will not be the villains in this movie, as they will ask Arlo and Spot to help them track down some raptors that are attacking their herd.
- A new trailer shows that Arlo and his family are going to be farmers after all, like in Bob Peterson's concept for the film. The Apatosaurus will also raise chickens as well as growing crops.
- The characters I've marked with an asterisk had their names revealed in the merchandise. Unfortunately, they did not appear in the final film because Peter Sohn wanted to make the plot simpler, and he reduced the dino-farmers just to Arlo and his family. However, that doesn't have to keep fans from telling their own stories with them.