Around the time Crichton wrote Jurassic Park, the latest scientific research was leaning toward a possibly closer relationship between birds and dinosaurs than paleontologists had previously thought. At the time the idea was still somewhat controversial. Since the book's publication, however, virtually irrefutable fossil evidence has been found linking the heritage of birds to dinosaurs. Nevertheless, many paleontologists have found the depiction of some of the dinosaurs in the movie version of Jurassic Park—the screenplay of which was partially written by Crichton himself—to be exaggerated and unrealistic, the velociraptors in particular being much too large and speedy. Nonetheless, this more recent research seems to have borne out the idea that dinosaurs, as ancestors of both modern-day lizards and birds, were more agile than previously thought.
As Jurassic Park is located on an island about a hundred miles off Costa Rica, InGen is, from the start, associated with the Costa Rican "hupia" spirits that are purported to dwell on offshore islands and kidnap children. The injured InGen worker claims that a hupia was responsible for his plight. These hupia prove to be the most notable symbol in the novel: after Tina is attacked, Dr. Guitierrez's research indicates that several babies around Costa Rica have recently been attacked by lizards. Bearing these events in mind, along with the fact that the injured InGen worker is described as "a boy," we infer at this point that the hupia have something to do with InGen and lizards.
Later, it is more than mere coincidence that the first big dinosaur attack happens to Tim and Lex. The dying guard's talk about hupia links the concept of the hupia to both the word "raptor" and the local lizard attacks. Once we become aware that InGen has been breeding dinosaurs—not mere lizards—the connection between hupia and the dinosaurs of Jurassic Park is obvious. Indeed, the dinosaurs InGen has created seem to instinctively attack children. Crichton uses this idea to vilify the dinosaurs, making them even more fearsome forces of evil than they might be if they were not especially targeting defenseless children.
In particular, the connection between the hupia and the velociraptors. When the tour group is in the raptor nursery at Jurassic Park, the baby raptor is clearly drawn to Tim. Later in the novel, when the raptors get loose, several of them go after Tim and Lex. As evidence grows that raptors have escaped to the mainland, the prospect of a whole population of intelligent, baby-hungry beasts hiding in the jungles of Costa Rica is made especially disturbing.