Jurassic Park - Fact or Fiction? The Real Dilophosaurus

In this Blog Series we will be looking at some Dinosaurs portrayed in the Jurassic Park film series, and compare the inaccurate film versions with Paleontological research, to get a better picture of the real dino.

Please note, I am a massive fan of the Jurassic Park / World franchise, and I still love the creativity of the films, this series is done out of scientific curiosity and interest.

Image Credits -  Left: Screencaps from Jurassic Park (1993 Film) / Right: An artist's interpretation of Dilophosaurus based on the latest research. Credit: Brian Engh / The Saint George Dinosaur Discovery Site.

Dilophosaurus was featured in the 1990 novel Jurassic Park, by the writer Michael Crichton, and its 1993 movie adaptation by the director Steven Spielberg. The Dilophosaurus of Jurassic Park was acknowledged as the "only serious departure from scientific veracity" in the movie's making-of book, and as the "most fictionalized" of the movie's dinosaurs in a book about Stan Winston Studios, which created the animatronics effects. 

Dilophosaurus Size Comparisons between Dilophosaurus Wetherilli and the Movie Version

For the novel, Crichton invented the dinosaur's ability to spit venom (explaining how it was able to kill prey, in spite of its seemingly weak jaws). The art department added another feature, a neck frill or cowl folded against its neck that expanded and vibrated as the animal prepared to attack, similar to that of the frill-necked lizard. To avoid confusion with the Velociraptor as featured in the movie, Dilophosaurus was presented as only 1.2 meters (4 ft) tall, instead of its assumed true height of about 3.0 meters (10 ft). Nicknamed "the spitter", the Dilophosaurus of the movie was realized through puppeteering, and required a full body with three interchangeable heads to produce the actions required by the script. Separate legs were also constructed for a shot where the dinosaur hops by. 

Unlike most of the other dinosaurs in the movie, no computer-generated imagery was employed when showing the Dilophosaurus. Of course, Crichton and Spielberg took artistic liberties to tell a compelling story, dramatizing not only the scientists but also the dinosaurs. The animal that departed most from the fossil evidence was Dilophosaurus. In the movie, it takes the form of a golden retriever–sized creature with a rattling frill and venomous spit that kills the computer programmer–turned–dinosaur embryo smuggler, Dennis Nedry.

The hallmarks of the cinematic Dilophosaurus—namely, its venomous saliva and collapsible frill—were also fictional traits added for dramatic effect. But these embellishments resembled the biology of other real animals, which made them believable. When Welles described the fossils of Dilophosaurus, he interpreted some of the joints between the tooth-bearing bones at the end of the snout as “weak” and suggested that the animals may have been scavengers or that they did most of their killing with claws on their hands and feet. When writing the story, Crichton invented a dramatic mechanism by which the animals could spit a blinding venom, based on some modern species of cobras, which can spit two meters. Inspiration for the frill, meanwhile, came from the modern-day frilled agamid lizard that lives in Australia and New Guinea. The lizard has a structure made of bone and cartilage originating from the throat that supports the frill.

The Dilophosaurus was probably not endowed with neck frill (borrowed from Australian frilled lizard) nor could spit venomous saliva (though its bite could have been poisonous due to bacteria developing in rotting meat in theropoddental serrations; bacterial toxins help the Komodo dragon in killing their prey).

Image Credits -  Left: Unknown, Middle: kuritafsheen / Getty Images, Right: Jurassic World Evolution (Video Game) 

If Dilophosaurus did have a frill, we would know about it. There would be fossil evidence of bones, or some other rigid structure required to hold the frill up and there would be markings on the bones of the neck indicating where muscles could attach that would be required to move the frill up and down. We don't see either of these. Dilophosaurus was too small in comparison to the large real life counterpart. 

Dilophosaurus Size Comparisons between Dilophosaurus Wetherilli and the Movie Version

Image Credit: Brian Engh (reconstructions) and Daisy Chung (family trees); Source: “A comprehensive anatomical and phylogenetic evaluation of Dilophosaurus wetherilli (Dinosauria, Theropoda) with descriptions of new specimens from the Kayenta Formation of northern Arizona,” by Adam D. Marsh and Timothy B. Rowe, in Journal of Paleontology, Vol. 94; July 2020 (family trees).

If Dilophosaurus indeed had an expandable skin collar around its neck (and that's total speculation), it certainly wouldn't have deployed it when facing a prospective meal (Nedry). That kind of display is more for intimidating prospective competitors (such as for mates or territory). Why would a carnivore try to intimidate its next meal?

The Real Dilophosaurus:

Dilophosaurus is a genus of theropod dinosaurs that lived in what is now North America during the Early Jurassic, about 193 million years ago. Scientists did not have a complete picture of the real Dilophosaurus, back when it entered pop culture. But in the nearly three decades since Dilophosaurus got the Hollywood treatment, researchers have recovered significant new fossil specimens of this dinosaur and analyzed all of the remains with increasingly sophisticated methods. As a result, we can now reconstruct this dinosaur, its appearance and behavior, how it evolved, the world it inhabited in detail. The findings show that the real Dilophosaurus bore little resemblance to its cinematic counterpart. They also provide the most detailed portrait yet of a dinosaur from the Early Jurassic epoch.

Image Credit: Chase Stone

Today we know Dilophosaurus as a bipedal, meat-eating dinosaur more than 20 feet long with two distinctive parallel crests of very thin bone along the top of its head (its name derives from the Greek words for “two-crested reptile”). But in 1954, when the animal first appeared in the scientific literature, it had a different name: in a series of papers, Samuel Welles, a University of California, Berkeley, paleontologist, presented his research on two skeletons found by Jesse Williams, a Navajo man who lived near Tuba City, Ariz. The crest had not been identified among the fragmentary remains, and Welles called the creature Megalosaurus Wetherilli, believing it to be a new species in the previously known genus Megalosaurus. When Welles found an additional specimen in 1964 that preserved the top of the skull, with its dual crests, he realized that the original find represented a new genus, so he renamed the animal Dilophosaurus Wetherilli.

https://commons.wikimedia.org/wiki/File:Dilophosaurus_Size_Comparison.svg#/media/File:Dilophosaurus_Size_Comparison.svg

Like many early dinosaurs and all modern birds, Dilophosaurus had fleshy air pockets from its respiratory system growing into its vertebrae, which provided strength while simultaneously lightening the skeleton. These air sacs allowed for the unidirectional flow of air through the lungs, the entire cycle occurs in one breath, as it does in birds and crocodilians. This type of respiration provides the animal with more oxygen than does the bidirectional respiratory system that mammals have, in which air flows both in and out of the lungs. Animals that breathe unidirectionally tend to have relatively high rates of metabolism and thus high activity levels, so Dilophosaurus was probably a fast, agile hunter.

New research has cast this dinol in a different light. In 2020, a Journal of Paleontology published a study that reevaluated five specimens of Dilophosaurus. It was found that the maxilla-premaxilla connection (the part of the maxilla which bears the incisor teeth, and encompasses the anterior nasal spine and alar region) was stronger than had been supposed previously by Paleontologists. They also observed scaffold-like attachment points for strong muscles on the lower jawbones. All this tells us Dilophosaurus actually had powerful jaws at its disposal. (Bite marks found on the remains of one Sarahsaurus, a large contemporary herbivore, may have been left behind by a peckish Dilophosaurus.)

So in conclusion, it seems like, the Real Dilophosaurus Would Have Eaten the Jurassic Park version for Breakfast.

References, bibliography & further reading:

Dinosaurs: A Visual Encyclopedia by DKPublishing 

https://www.amazon.com/Visual-Encyclopedia-Dinosaurs-DK-Publishing/dp/1405308389

Duncan, J. (2007). The Winston Effect: The art and history of Stan Winston studio. London, UK: Titan Books.

Bennington, J.B. (1996). "Errors in the movie Jurassic Park". American Paleontologist

https://www.scientificamerican.com/article/the-real-dilophosaurus-would-have-eaten-the-jurassic-park-version-for-breakfast/

https://animals.howstuffworks.com/dinosaurs/dilophosaurus.htm

https://www.nationalgeographic.com/animals/reptiles/facts/frilled-lizard