The dinosaurs of Jurassic Park may have been the first photorealistic computer-generated animals to grace the big screen, but in the 20 years since then, filmmakers have used computers to simulate more familiar lifeforms — sometimes for safety reasons, sometimes because it gives the filmmakers more control over the animals’ actions, and sometimes because it’s just more cost-effective. See, for example, the horses that were crushed underfoot during one of the big battles in The Lord of the Rings, or the tiger and other animals that shared a lifeboat with a human shipwreck survivor in Life of Pi.
And it’s not just animals. Just last night I was watching the iTunes commentary for Star Trek into Darkness, and one of the special-effects guys mentions quite casually that “literally fifty percent” of the aliens who worship the Enterprise at the end of that film’s opening sequence were actors in make-up, and the rest were created in a computer. And this, despite the fact that there are only a few dozen characters onscreen and they are relatively close to the camera; we’re not talking about one of those epic cast-of-thousands shots like the ones Peter Jackson popularized.
So it should come as no surprise that movies based on the story of Noah’s Ark have been turning to computers to create their little zoos, too.