The Dilophosaurus, whose name translates to “two-crested lizard,” was a large predatory dinosaur that lived during the Early Jurassic Period. This theropod is distinguished by the pair of delicate, bony crests that run longitudinally along the top of its skull. The animal was a significant carnivore in its ecosystem, representing one of the first large meat-eaters to roam the continent. Understanding the world of Dilophosaurus requires looking beyond its unique anatomy to the specific geological record that preserved its remains.
Identifying the Dilophosaurus
Dilophosaurus wetherilli was a medium-sized theropod, a group of bipedal, mostly carnivorous dinosaurs that includes later giants like Tyrannosaurus. Reaching an imposing length of about 23 feet (7 meters) and weighing approximately 880 pounds (400 kg), it was the largest known land animal in North America during its time, about 193 million years ago. Its overall build was slender and lightweight, suggesting a fast and agile predator.
The most recognizable feature of this dinosaur is the pair of thin, arched crests positioned on the top of its skull, stretching from the nose to behind the eyes. These crests were likely too fragile to be used in physical combat, leading scientists to hypothesize they served as a visual display for species recognition or sexual selection. Furthermore, the snout was narrow and possessed a distinctive gap, or kink, between the premaxilla and maxilla bones of the upper jaw. This anatomical feature initially led some paleontologists to believe the dinosaur was a scavenger with weak jaws, though more recent research suggests it had a stronger jaw structure than previously thought.
The Primary Fossil Evidence
The physical evidence of Dilophosaurus existence is almost entirely confined to the southwestern United States, specifically in northern Arizona. The most complete specimens were discovered within the Kayenta Formation, a geological unit rich with Early Jurassic fossils. The initial discovery of three skeletons occurred in 1940 near Tuba City on the Navajo Indian Reservation.
Paleontologist Samuel P. Welles formally named the dinosaur in 1970 after realizing one of the larger specimens he collected in 1964 bore the distinctive double crests. The Kayenta Formation consists of reddish-brown siltstone and sandstone deposited by ancient river systems and floodplains approximately 195 to 185 million years ago. The specific strata where Dilophosaurus was found confirm its age as Early Jurassic, making it a valuable index fossil for that time period in North America.
Life in the Early Jurassic Habitat
The Kayenta Formation environment that Dilophosaurus inhabited was a low-lying terrestrial landscape dominated by ancient river systems and floodplains. Although the area was part of a broader arid environment, the presence of these river deposits and small lakes suggests a fluctuating seasonal climate that supported a diverse ecosystem. This landscape was a network of braided streams and rivers that would seasonally swell and recede, creating the perfect conditions to preserve the footprints and skeletal remains of its inhabitants.
The flora of this world included ferns, cycads, horsetails, and conifers, providing a food base for the herbivorous fauna. Dilophosaurus shared its territory with other animals, including the early armored dinosaur Scutellosaurus and the long-necked sauropod relative Sarahsaurus. The large size of Dilophosaurus indicates it was the apex predator, likely hunting these smaller or less-defended contemporaries in an environment centered around the river valleys.
Fact Versus Fiction
The public image of Dilophosaurus is often significantly shaped by its portrayal in popular media, which introduced several features not supported by the fossil record. The most enduring misconceptions are the dinosaur’s supposed ability to spit venom and the presence of a large, retractable neck frill. There is no anatomical evidence in the skull or skeleton of Dilophosaurus to suggest it possessed venom glands or the complex muscular and skeletal structure required for a frill.
The fictionalized version also drastically reduced the dinosaur’s true size, depicting it as a smaller, human-sized creature. In reality, Dilophosaurus measured up to 23 feet long and was a formidable predator, not a small, stealthy one.