Dilophosaurus wetherilli was a large meat-eating dinosaur that lived during the Early Jurassic Period, about 193 million years ago. It is famous for the two thin, arched crests on top of its skull, which make it one of the most recognizable theropods. Fossils from Arizona show that it was a fast, long-legged predator in semi-arid environments with rivers, floodplains, and seasonal changes.
Studying Dilophosaurus helps paleontologists understand how early large theropods evolved before later giants like Allosaurus and Tyrannosaurus.
The paired crests were probably too thin for fighting, so they may have helped with display, species recognition, or attracting mates. Its skull had a long snout and sharp teeth, while its body was built for active movement with strong hind limbs and a balancing tail. Paleontologists use fossil bones, trackways, rock layers, and comparisons with living animals to reconstruct how Dilophosaurus moved, fed, and interacted with its environment.
Popular media often shows it with a neck frill and venom, but there is no fossil evidence for either feature.
Key Facts
- Scientific name: Dilophosaurus wetherilli.
- Time period: Early Jurassic, about 193 million years ago.
- Estimated length: about 6 to 7 m from snout to tail.
- Estimated mass: about 300 to 400 kg, depending on the reconstruction.
- Speed relationship: speed = distance ÷ time.
- Fossil age estimate: 1 million years = 1,000,000 years, so 193 million years = 193,000,000 years.
Vocabulary
- Theropod
- A group of mostly meat-eating dinosaurs that walked on two legs and includes Dilophosaurus, Velociraptor, and modern birds.
- Crest
- A raised structure on an animal's body, such as the paired bony ridges on the skull of Dilophosaurus.
- Fossil
- Preserved evidence of ancient life, such as bones, teeth, footprints, or impressions in rock.
- Paleontology
- The scientific study of ancient life using fossils and the rocks that contain them.
- Early Jurassic
- The first part of the Jurassic Period, lasting from about 201 to 174 million years ago.
Common Mistakes to Avoid
- Adding a neck frill to Dilophosaurus is wrong because no fossil evidence shows that it had one.
- Saying Dilophosaurus definitely spat venom is wrong because venom glands and venom-spitting behavior are not preserved or supported by its known fossils.
- Calling the head crests horns for stabbing is wrong because the crests were thin and delicate, making display or recognition more likely than combat.
- Assuming every dinosaur in the Jurassic lived with every other famous dinosaur is wrong because species lived in different times and places, often separated by millions of years.
Practice Questions
- 1 A Dilophosaurus fossil is dated to 193 million years old. Write this age in years using standard notation.
- 2 If a Dilophosaurus walked 180 m across a floodplain in 60 s, what was its average speed in m/s?
- 3 A fossil skull has two thin, paired crests but no evidence of a frill or venom structures. Explain why a paleontologist should be careful about claiming that the animal used venom or had a neck frill.