Jurassic Park, a book by Michael Crichton, with a film version directed by Steven Spielberg, revolves around the resurrection of dinosaurs via genetic engineering. Scientists and enthusiasts have brought up a number of issues with facts and feasibility. Some of the speculative or inaccurate features attributed to the dinosaurs of Jurassic Park have become embedded in popular culture, most popular among them being the idea of Tyrannosaurus only seeing motion; giant, feather-less, intelligent velociraptors, and dwarf, frilled, poison-spitting Dilophosaurus. In general, the novel is more accurate than the film, with Spielberg adding some features to the dinosaurs (like the frill on the dilophosaurs).