Michael Crichton and David Koepp

Michael Crichton's novel Jurassic Park was published in 1990. Crichton, as a novelist, was famous for novels that explored sci-fi quandaries, like finding a spaceship at the bottom of the ocean in Sphere (1987) or deadly bio-organisms in The Andromeda Strain (1969). He also created a TV show you may have heard of—ER—featuring actors like George Clooney and Julianna Margulies who have gone on to pick up bit parts here and there over the years.

Spielberg and Crichton worked together on ER, which is where Spielberg first heard of Crichton's upcoming dinosaur novel. Immediately, Spielberg had dinosaurs on the brain. So Crichton teamed with David Koepp to transform the more cerebral novel into a more action-packed summer blockbuster.

Koepp had previously written the Meryl Streep/Goldie Hawn dark comedy Death Becomes Her (1992), so he was no stranger to big personalities and incredible special effects. After the runaway success of Jurassic Park, Koepp went on to write future blockbusters, including the first Tobey Maguire Spider-Man (2002) and Tom Cruise's War of the Worlds (2005).

Jurassic Park made lots of changes to Crichton's novel. Crichton's novel kills off John Hammond and Ian Malcolm, and it features more dinosaurs, like Stegosaurus and the flying Cearadactylus. The movie kept both characters alive, though, and omitted some dinosaurs for technical and budgetary reasons. Due to the success of Jurassic Park's film adaptation, Crichton wrote the sequel after the movie, and even revived the presumed-dead Ian Malcolm as the sequel's main character. Clever guy.