who discovered it?
Samuel P. Welles
Dilophosaurus
The most complete specimen became the holotype of a new species in the genus "Megalosaurus", named "M. wetherilli" by Samuel P. Welles in 1954. Welles found a larger skeleton belonging to the same species in 1964. Realizing it bore crests on its skull, he assigned the species to the new genus "Dilophosaurus" in 1970, as Dilophosaurus wetherilli. 
what is the dinosaur in jurassic park that spits UNANSWERABLE what is dilophosaurus? It is a genus of theropod dinosaurs
wiki:1878740
Dilophosaurus [SEP] Introduction
Due to the limited range of movement and shortness of the fore limbs, the mouth may instead have made first contact with prey. The function of the crests is unknown; they were too weak for battle, but may have been used in visual display, such as species recognition and sexual selection. It may have grown rapidly, attaining a growth rate of per year early in life. The holotype specimen had multiple paleopathologies, including healed injuries and signs of a developmental anomaly. "Dilophosaurus" is known from the Kayenta Formation, and lived alongside dinosaurs such as "Megapnosaurus" and "Sarahsaurus". "Dilophosaurus" was featured in the novel "Jurassic Park" and its movie adaptation, wherein it was given the fictional abilities to spit venom and expand a neck frill, as well as being smaller than the real animal.