"The raptors in the novel, following through to the film raptors, were larger than the species going by the name because during the writing of the novel, a previously discovered dinosaur named Deinonychus (closely related to Velociraptor, but larger) was interpreted as a Velociraptor species by some scientists, notably Gregory S. Paul. In fact, in the novel, Deinonychus is mentioned, but the character Alan Grant then says that scientists have reclassified it as a species of Velociraptor. Crichton wrote his novel based on the idea of a human sized raptor, but after the publication, when the film was already in production, the idea of Deinonychus being a Velociraptor species was dropped by the scientific community.
During the film's production, the effects supervisors acknowledged that the Velociraptor featured in the movie were sized identically to the larger Deinonychus. However, during filming, paleontologists came across a larger dromaeosaurid species named Utahraptor and the larger raptors remained, even though Utahraptor was substantially larger (21 feet long) than the film's raptors. It should be noted, also, that at the start of the film, a Velociraptor skeleton is uncovered in Montana; no examples of the dinosaur have been uncovered in the United States (although both Deinonychus and Utahraptor are American dinosaurs). The fossil skeleton is similarly inaccurately large. It is possible that the Velociraptors in the film are re-classified Deinonychus, though in the book they are said to be Velociraptor mongoliensis.
The high intelligence of the film's velociraptors are considered somewhat unlikely by scientists, given the relative size of their brains and comparisons with modern animals.
It is certain that Velociraptor had feathers. Neither the film nor the novel dinosaurs had feathers; however, both were created before the discovery of feathered dinosaurs closely related to Velociraptor (e.g. Microraptor). In Jurassic Park III, the raptors were remodelled and small feathers on the males' heads were included, while still looking similar to the original design.As with other bipedal dinosaurs in the films, the hands of Velociraptor are depicted with the palms able to rotate, but this would have been anatomically impossible for the real animals, as their forearm bones (ulna and radius) could not rotate in this way. Their palms should have been relatively fixed facing each other, like a person about to applaud."