 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 . 
