Jurassic Park was a technological breakthrough in the area of digital effects. However, the film was so ahead of its time that the writer of the script wasn't even sure if the stuff he was writing was going to be possible to film. David Koepp, who wrote the screenplay for Steven Spielberg's blockbuster, says there was one scene in particular that he didn't think would actually be filmable because it called for things effects had never done before.

I wrote a line in one of my first drafts that said 'The T-Rex bursts out of the trees, chases down the Gallimimus, and devours it in a cloud of dust and blood.' I thought, 'Well I love that line, and I'd love to see that.' But I asked Steven, 'This seems impossible to me, should I take it out? Should I do it another way? What are my limitations.' And he said, 'Your imagination, that's the only limit you have. We'll figure it out.' But I knew that the real challenge was running. In the movies, if you see a dinosaur and his feet are in the shot it's probably a puppet or one of Stan Winston's creations. If you see the legs and it walks, that's CG, but that's what nobody knew if it would work or not. So, much less running out of the foliage and eating another dinosaur in a wide shot.

The digitally created dinosaurs in Jurassic Park still hold up remarkably well considering their age at this point. However, at the time nobody had any idea that would be the case. In all honesty, Steven Spielberg probably wasn't helping my matters by telling his screenwriter that his imagination was his only limit. He was apparently quite confident that they'd be able to make anything happen, and while it's true that you can make almost anything work digitally, they didn't know that then. A great deal is still possible using practical effects, but as Koepp points out to Collider, you often need to modify what you're shooting in order to make it work. It could have very easily been the case for digital effects as well.

And yet, Steven Spielberg was right. Something that could not have been realistically done previously was made to look as real as anything when Jurassic Park was completed.

What's interesting is how this shot hardly looks like it would have been one of the most difficult to shoot. It's fascinating to have David Koepp explain why this particular interaction would have been so difficult, compared to everything else that dinosaurs do in the film.