Epigraphs are like little appetizers to the great main dish of a story. They illuminate important aspects of the story, and they get us headed in the right direction.
"Reptiles are abhorrent because of their cold body, pale color, cartilaginous skeleton, filthy skin, fierce aspect, calculating eye, offensive smell, harsh voice, squalid habitation, and terrible venom; wherefore their Creator has not exerted his powers to make many of them." — Linnaeus, 1797
"You cannot recall a new form of life." — Erwin Chargaff, 1972
What's up with the epigraph?
The two quotes that begin the novel are somewhat ironic.
The first, by the Swedish natural scientist Carl Linnaeus, is ironic because the novel Jurassic Park presents dinosaurs as more bird-like than reptile-like, even though they're still fierce and terrible. More importantly, the novel tells the tragic tale of John Hammond's disastrous attempt to make many, many dinosaurs. Linnaeus's Creator had more sense.
The second quote by the famous biochemist Erwin Chargaff is interestingly placed, given the fact that the dinosaurs in the novel are not exactly old creatures reborn; in a way, they're something distinct and artificial, a new form of life. Chargaff's point was that once you create new life, that new life takes on a life of its own. No take-backs. This, of course, is what we see in Jurassic Park. Destroying the island doesn't destroy all of the dinosaurs. Some have escaped, and they cannot be recalled.