<P> To create the dinosaurs, Spielberg at first thought of hiring Bob Gurr, who designed a giant mechanical King Kong for Universal Studios Hollywood's King Kong Encounter . Upon considering that the life - sized dinosaurs would be too expensive and not all convincing, Spielberg instead sought the best effects supervisors in Hollywood . Brought in were Stan Winston to create the animatronic dinosaurs, Phil Tippett to create go motion dinosaurs for long shots credited as Dinosaur Supervisor, Michael Lantieri to supervise the on - set effects, and Dennis Muren of Industrial Light & Magic to do the digital compositing . Paleontologist Jack Horner supervised the designs, to help fulfill Spielberg's desire to portray the dinosaurs as animals rather than monsters . This led to the entry of certain concepts about dinosaurs, such as the theory that dinosaurs evolved into birds and had very little in common with lizards . One of the first consequences was the removal of the raptors' flicking tongues in Tippett's early animatics, as Horner complained it was implausible . Winston's department created fully detailed models of the dinosaurs before molding latex skins, which were fitted over complex robotics . Tippett created stop - motion animatics of both the raptors in the kitchen and the Tyrannosaurus attacking the car . But despite go motion's attempts at motion blurs, Spielberg still found the end results unsatisfactory in terms of working in a live - action feature film . Muren declared to Spielberg that he thought the dinosaurs could be built through computer - generated imagery, and the director asked him to prove it . ILM animators Mark Dippé and Steve Williams developed a computer - generated walk cycle for the T. rex skeleton, and were approved to do more . When Spielberg and Tippett saw an animatic of the T. rex chasing a herd of Gallimimus, Spielberg said, "You're out of a job," to which Tippett replied, "Don't you mean extinct?" Spielberg later injected this exchange into the script, as a conversation between Malcolm and Grant . Although no go motion was used, Tippett and his animators were still used by the production to supervise dinosaur movement . Tippett acted as a consultant regarding dinosaur anatomy, and his stop motion animators were re-trained as computer animators . The animatics made by Tippett's team were also used along with the storyboards as a reference for what would be shot during the action sequences . ILM's artists were sent to private tours to the local animal park so they could study large animals--rhinos, elephants, alligators, and giraffes--up close, and also received mime classes for understanding movements . </P> <P> Universal paid Crichton a further $500,000 to adapt his own novel, which he had finished by the time Spielberg was filming Hook . Crichton noted that because the book was "fairly long" his script only had about 10 to 20 percent of the novel's content; scenes were dropped for budgetary and practical reasons, and despite the gory descriptions, the violence was toned down . Malia Scotch Marmo began a script rewrite in October 1991 over a five - month period, merging Ian Malcolm with Alan Grant . </P> <P> As Spielberg wanted another writer to rework the script, Universal president Casey Silver recommended him David Koepp, co-writer of Death Becomes Her . Koepp started afresh from Marmo's draft, and used Spielberg's idea of a cartoon shown to the visitors to remove much of the exposition that fills Crichton's novel . While Koepp tried to avoid excessive character detail "because whenever they started talking about their personal lives, you couldn't care less", he tried to flesh out the characters and make for a more colorful cast, with moments such as Malcolm flirting with Sattler leading to Grant's jealousy . Some characterizations were changed from the novel . Hammond went from a ruthless businessman to a kindly old man, because Spielberg identified with Hammond's obsession with showmanship . He also switched the characters of Tim and Lex; in the book, Tim is aged eleven and interested in computers, and Lex is only seven or eight and interested in sports . Spielberg did this because he wanted to work with the younger Joseph Mazzello, and it also allowed him to introduce the sub-plot of Lex's adolescent crush on Grant . Koepp changed Grant's relationship with the children, making him hostile to them initially to allow for more character development . </P> <P> Two scenes from the book were ultimately excised, with Spielberg removing the opening sequence with Procompsognathus attacking a young child as he previously found it too horrific, and Koepp cutting for budgetary reasons the T. rex chasing Grant and the children down a river before being tranquilized by Muldoon . Both parts eventually saw inclusion in the film sequels . Spielberg suggested the addition of the scene where the T. rex pursues a jeep, which at first would only have the characters driving away after listening to the dinosaur's footsteps . </P>

How old are lex and tim in jurassic park movie
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