According to visual effects supervisor Ed Jones, there are two big differences between CGI dinosaurs and CGI dogs and cats. One is fur, which has been one of the most difficult things to replicate in the digital realm. The other is familiarity. "With something like Jurassic Park," says Jones, talking about his latest project, Cats & Dogs, "you've never a dinosaur, so there's a lot of leeway in creating them. But you've seen cats and dogs—people live with them, and love them.