Research reviewed 30 July 2026. Scientific interpretations may change as new evidence is published.
Dilophosaurus wetherilli was a large meat eating dinosaur that lived in what is now Arizona about 184 million years ago. It had two thin head crests, a light but strongly built skeleton and none of the venom or folding neck frill made famous by films.
| Fact | Answer |
|---|---|
| Scientific name | Dilophosaurus wetherilli |
| Name meaning | Two crested lizard |
| Period | Early Jurassic |
| Age | About 184 million years ago |
| Fossil location | Northern Arizona, USA |
| Diet | Carnivore |
| Length | About 6 to 7 metres |
| Mass | Roughly 400 kilograms, although estimates remain approximate |
Dilophosaurus was an early large theropod, part of the mainly two legged dinosaur group that also includes later predators and modern birds. It was not as massive as Tyrannosaurus rex, but it was one of the largest hunters in its Early Jurassic environment.
Its most recognisable features were two long crests running along the top of its skull. The name Dilophosaurus means “two crested lizard”. The crests were made from thin bone and may have carried a larger covering of keratin, the material found in bird beaks and human fingernails.
The first skeleton was discovered in 1940 by Jesse Williams, a Navajo man who showed the site to a scientific expedition.
Dilophosaurus lived during the Early Jurassic, about 184 million years ago. This was more than 115 million years before T. rex. Its fossils come from the Kayenta Formation of northern Arizona, including land within the Navajo Nation.
The environment had rivers, sandy channels and seasonal dry periods. Ferns, cycads and conifers grew there. Dilophosaurus shared this landscape with smaller plant eaters, early armoured dinosaurs, crocodile relatives and other reptiles.
An adult Dilophosaurus was about 6 to 7 metres long and may have weighed roughly 400 kilograms. The estimate is uncertain because no complete skeleton has been discovered. It walked on two long hind legs and used a stiff tail for balance.
Its well developed forelimbs ended in grasping hands. The skull had air spaces that reduced its weight while strong connections joined its bones. A major anatomical study published in 2020 showed that older drawings had placed some bones incorrectly and made the skull seem weaker than it really was.
The twin crests were probably too delicate for hard fighting. They may have helped individuals recognise one another or could have been used in courtship display. Their colour is unknown because colour pigments have not been preserved.
Dilophosaurus was a carnivore. Its jaws carried curved, serrated teeth for gripping and cutting flesh. Scientists once suggested that its skull was too weak for active hunting, but the revised reconstruction supports a more capable predator.
Bite marks and shed teeth found near bones of the plant eating dinosaur Sarahsaurus may record feeding by Dilophosaurus. However, association alone cannot tell researchers whether it made the kill or found a carcass. Fish may also have been part of its diet, but there is no direct evidence that it specialised in catching them.
The first fossils included a partial skeleton, and further specimens added missing parts of the skull and body. Together they revealed the paired crests and helped scientists correct mistakes in the original reconstruction.
The bones also preserve signs of growth and injury. One individual had damage to its shoulder and forelimb, showing that it survived serious problems for a time. Comparing several skeletons allows researchers to separate normal anatomy from injury or distortion caused while a fossil was buried.
No fossil shows a folding neck frill, poison gland or venom delivery groove. Those features were invented for entertainment and should not be treated as scientific evidence.
The main debate concerns the crests. Display and recognition are sensible explanations, but fossils cannot show exactly what another Dilophosaurus saw or how the crests changed with age. Scientists also do not know their original colours.
Researchers continue to study its relationships to other early theropods, the strength of its bite and the range of prey it could tackle. Whether its body carried simple feathers is also unresolved because no skin covering has been found with the known skeletons.
The real Dilophosaurus was not a small animal with a folding neck frill. It was around 6 to 7 metres long, and no frill is present in its fossils. There is no evidence that it spat venom or produced venom at all. Its crests were probably display structures rather than heavy weapons. Describing it as a weak scavenger also ignores newer research showing a more strongly built skull. Finally, Dilophosaurus did not meet T. rex because the two lived in very different parts of geological time.
The name means “two crested lizard”, referring to the paired crests on its skull.
It lived in the Early Jurassic, about 184 million years ago.
The best known fossils come from northern Arizona in the USA, on land within the Navajo Nation.
It was about 6 to 7 metres long and may have weighed roughly 400 kilograms.
Their exact purpose is unknown, but display, courtship and recognition are leading ideas.
No fossil evidence supports venom, poison glands or a venom delivery system.
No. The frill was created for fiction and is not present in the skeleton.
Its anatomy supports active hunting, although it may also have scavenged when food was available.
