Dilophosaurus, a large theropod dinosaur from the Early Jurassic Period, has captivated public imagination due to its unique and striking appearance. The most recognizable feature of this animal is the pair of thin, arched crests that ran along the top of its skull. As one of the earliest large predatory dinosaurs, studying its remains provides significant insights into the terrestrial ecosystems that existed just after the Triassic-Jurassic extinction event.
The Primary Discovery Location
The first specimens of Dilophosaurus were unearthed in the deserts of North America, specifically in northern Arizona, USA. The initial discovery occurred in 1940 on land now part of the Navajo Nation, near the community of Tuba City. A Navajo man named Jesse Williams first encountered the fossil bones and brought them to the attention of paleontologists. The subsequent collection effort in 1942 was led by a University of California Museum of Paleontology team, which recovered the two best-preserved skeletons from the site in Navajo County. These fossils, including the holotype specimen, were found in close proximity, providing an unprecedented look at this early large predator.
Geological Context: The Kayenta Formation
The remains of Dilophosaurus were preserved within the Kayenta Formation, a geological stratum extensively studied in the American Southwest. This formation dates to the Early Jurassic Period (Sinemurian and Pliensbachian stages), placing the dinosaur’s existence approximately 193 to 183 million years ago. The ancient environment was a complex system of river floodplains, transient lakes, and dune fields, dramatically different from the arid conditions of modern Arizona. This setting was characterized by seasonal wet and dry cycles, providing a mosaic of habitats for the local fauna. Dilophosaurus shared this environment with other early dinosaurs, including the small, armored ornithischian Scutellosaurus and the early sauropodomorph Sarahsaurus.
Scientific History and Reassessment
The scientific study of the Dilophosaurus fossil began with confusion following its excavation. Paleontologist Samuel Welles, the primary researcher of the initial material (a fragmentary skull lacking ornamentation), initially classified the creature as Megalosaurus wetherilli in 1954. A more complete specimen, discovered in 1964 and featuring the intact crests, prompted Welles to re-examine the fossils. He recognized the unique nature of the dinosaur and assigned it to the new genus Dilophosaurus—meaning “two-crested lizard”—in 1970.
Modern Reassessment
More recent scientific reassessments, particularly a comprehensive review in 2020, have challenged older assumptions that the dinosaur had a fragile skull and weak bite. These newer analyses indicate that Dilophosaurus possessed a more robust jaw structure and was likely a powerful, top-tier predator. The popular media depiction of the animal spitting venom or sporting an extendable neck frill is not supported by the fossil record.