For most dinosaurs, the stakes were high. If you’re going to make a T. rex, you’d better do it right. The same went for Brachiosaurus, Parasaurolophus, Triceratops, and other paleo personalities that had been found during the late 19th and early 20th century bone rushes. But, taking a cue from Michael Critchon’s novel, the movie also cast a dinosaur that was unknown in Hollywood circles. Compared to its high-profile costars, Dilophosaurus was a newcomer with a complicated backstory.

The tale of Dilophosaurus goes back to a time after “the second Jurassic dinosaur rush” but long before modern dinomania kicked in. At the close of the summer 1942 field season, Sam Welles of the University of California