What Is A Dilophosaurus?

Dilophosaurus was a roughly 7-metre, 400 kg theropod dinosaur that lived in what is now Arizona about 193 million years ago in the Early Jurassic. Named for the two thin bony crests on top of its skull, it was the largest land predator of its time. Jurassic Park's frilled, venom-spitting version is fiction — a 2020 study (Marsh & Rowe) confirmed Dilophosaurus was actually large, powerfully built, and had no evidence of spitting venom or a neck frill.

You probably remember the scene from Jurassic Park—when Dennis Nedry (the nerdy computer programmer) nearly makes his escape from the island after stealing all the dinosaur DNA, only to crash his Jeep, then be spat on and devoured by a swarm of dinosaurs in the middle of the movie’s climactic storm? Those small creatures had poisonous venom and a huge frill around their heads in the movies, and were called Dilophosaurus in the books by Michael Crichton, but was that an accurate depiction? Were these dinosaurs vengeful pack hunters with such a Hollywood-friendly edge? Not exactly.

While you probably know not to trust Hollywood magic, it’s time we clear the air about the Dilophosaurus and set the record straight!

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What Is A Dilophosaurus?

Dilophosaurus is a genus of terrestrial theropod dinosaurs that lived approximately 190-193 million years ago, during the beginning of the Jurassic period.

An adult Dilophosaurus likely weighed around 400 kg (about 900 pounds) and stretched roughly 7 metres (around 20–23 feet) from snout to tail tip, much of that length being neck and tail. That made it the largest land predator known from its time — bigger than a tall man at the hips, and longer than a small car. The dinosaur had moderately sized arms and long fingers, with one prominent finger ending in a large curved claw.

The dinosaur stood on two feet, was a fast, slender and agile predator, and probably sat very much like modern-day birds—though they likely did not have feathers! Its unique jaw construction only featured a weak connection between the upper and lower jaw, meaning that it wouldn’t have had a very powerful bite. As a result, it is believed that these dinosaurs either fed on small creatures (perhaps even fish!) or hunted in packs in order to bring down larger prey. Some have even proposed that these creatures scavenged from dead carcasses, due to their unusually weak bite.

The genus was discovered in 1942 in the Kayenta Formation near Tuba City, Arizona. A local Navajo man, Jesse Williams, led members of a UCMP field party (under Charles Camp) to a site he had found years earlier, which turned up three partial theropod skeletons. Paleontologist Sam Welles formally described them in 1954. A more complete, larger specimen with the now-iconic double crests was excavated by Welles in 1964 — and finally prompted the move to a new genus.

In 1954, Welles initially classified the animal in the British catch-all genus Megalosaurus, calling it Megalosaurus wetherilli. Sixteen years later, in 1970, he renamed it Dilophosaurus — from the Greek for “two-crested lizard” — once the well-preserved 1964 skull revealed two thin, parasagittal crests running along the top of the head. (The 1942 skulls were too poorly preserved to show them at first.) Most paleontologists today think the crests were too fragile for combat and probably served as visual display structures.

Spitting Dinosaur: A Hollywood Exaggeration

While Jurassic Park may have brought the idea of a dilophosaurus into the public consciousness, the directors and producers weren’t overly worried about accuracy. For one thing, the dilophosaurus was the only dinosaur represented in the movie that was actually from the Jurassic Era, with the other six major species being found in the Cretaceous. More specifically though, the depiction of dilophosaurus as a small, dog-sized dinosaur is objectively false.

The most dramatic scene involving this dinosaur is when a large pack of these dinosaurs attacks the hapless villain of the story as he tries to make his escape. While some experts believe that these dinosaurs could have used their crests for communication, and pack hunting, there is no clear evidence that they spent time in such concentrated numbers. Furthermore, one of the dinosaurs dramatically spits venom into the villain’s face, but there is also no evidence for this as a defensive maneuver or an attack strategy in the full-sized Dilophosaurus discovered in Arizona.

The frills around the dinosaurs neck that spread open and scares the dickens out of Dennis Nedry (played by actor Wayne Knight, of Seinfeld fame), are also a piece of fiction. They vaguely resemble the same crests that would have been found on this dinosaur’s head, but they were highly exaggerated in size. All of that being said, Hollywood is known to take liberties with far worse details!

A Final Word

Though your first introduction to this species of dinosaurs was anything but accurate, now you know the truth of these mighty creatures, some of the strongest and fastest theropods of the early Jurassic Period. Not only that, but given their high metabolic demands, some paleontologists argue that these could have been warm-blooded animals, which connects to the fascinating evolution of endothermy, which developed more than once in the history of life on this planet!

What we’ve learned since 2020

The most thorough modern look at Dilophosaurus came in 2020, when Adam Marsh and Timothy Rowe published a 100-page redescription in the Journal of Paleontology based on five Arizona specimens. Their conclusions overturned the older “fragile-jawed scavenger” image: the skull was robust and reinforced with internal air sacs (much like modern birds), the muzzle was probably more powerfully built than once assumed, and Dilophosaurus was almost certainly a true apex predator rather than a wimpy fish-eater. Their phylogenetic analysis also moved it out of the coelophysoid grade and reclassified it as an early, large-bodied neotheropod — an evolutionary stepping stone toward the giant theropods that would dominate the rest of the Jurassic.