Entertainment Weekly has the answer:
Pixar announced two very peculiar animated features, both of them what-if concepts that immediately raised more questions than the studio was ready to answer.
“We’re going to announce two new films no one has ever heard about. Original films,” emphasized Pixar and Disney animation chief John Lasetter [sic], rousing cheers from the auditorium at Disney’s D23 fan convention, where the news was revealed. “You’re the very first group anywhere in the world to hear what these are about. But I’m not going to tell you about it. I’m going to let the filmmakers tell you.”
So are we …
First up was director Bob Peterson (also known as the voice of grouchy secretary Roz in Monsters Inc. and Doug the squirrel-distracted dog in Up) who revealed he is overseeing The Untitled Pixar Movie About Dinosaurs! (That’s what the jokey title card said on the screen above him.) It’s due in theaters around the holidays in 2013.
It has an unusual twist that sets it apart from other dino-animations like, say, The Land Before Time and Disney’s own prehistoric CG-fest Dinosaur. It’s a contemporary dinosaur tale, but also not Jurassic Park. Peterson explains: “Science tells us that an asteroid put an end to the dinosaurs 65 million years ago. In our movie the asteroid missed the Earth and dinosaurs continued to live.”
He then showed a piece of early concept art featuring what looked to be a leaner kind of brontosaurus, backlit at sunset in a golden field with a little, fuzzy-haired, human-looking child riding on the nape of its neck. “The inspiration for this came from when I was a little kid, and my mom and dad took me to the New York World’s Fair and I got to see something amazing — the animatronic dinosaurs created by Walt Disney. It made a big impression on me,” Peterson said.
Next up was a new project from Up and Monsters Inc. director Pete Docter, who had an even higher-concept film to announce, aiming for Summer 2014.
“At Pixar we love to explore new worlds,” Docter said. “We’ve taken you from the depths of the ocean, to the mountains of South America, from Monstropolis to outer space. We’re excited to take you somewhere everyone has been to, but no one has ever seen.”
All right … Docter paused while the audience tried to solve that riddle, then tapped his temple: “The world inside your own mind.”
That brought another (temporary) title: The Untitled Pixar Movie that Takes You Inside the Mind.
“Do you ever wonder how people make decisions? Why we remember, or how we forget? Why we dream? Why do songs get stuck in our heads?” Docter asked. “Most of us have had the experience of being around someone and thinking what is going on in their head!? This film will attempt to answer those questions.”
“We can’t wait to tell you more about it,” said producer Jonas Rivera. “As soon as we’re out of psychotherapy.”