The first Jurassic Park was hailed as a triumph of visual effects when it came out, but there are actually only five scenes that depended on CGI creatures. The rest of the time, the dinosaurs were animatronics. The video above shows you exactly how each of those scenes were put together.
One of the most interesting things is that the scene with the T-Rex attacking the Jeep also had a computer generated car. Apparently, they did originally have a real Jeep, but it didn't work and had to be painted out.
Back then, it took between 2-6 hours to render a single frame of the special effects, which, along with the expense, accounts for the small amount of CG use in the film. In this case, the less-is-more approach to CGI really does work. Fingers crossed that the upcoming Jurassic World remembers that. [via Slashfilm]