Dilophosaurus

Name and Popular Culture

Size and Comparison

Discovery and Naming

Dilophosaurus was first discovered in 1942 by Charles L. Camp, a paleontologist from the University of California Museum of Paleontology. He discovered three specimens in the Kayenta Formation in Northern Arizona. Of these, one was almost complete, one was quite eroded but still included several important pieces such as the front of the skull (which was missing in the first specimen), jaws, vertebrae, and limb bones. The third was almost completely gone. A number of other specimens have since been found.
Initially, it was thought to be a species of Megalosaurus and was given the name M. wetherilli. In 1970, it was given the name Dilophosaurus wetherilli.

Feathers: Evidence and Debate

It is not clear whether Dilophosaurus had feathers. Some trace fossils have been suggested to show evidence of feathers, but not all researchers agree; some argue that these impressions are actually artifacts caused by the dinosaur moving.

Skull Structure and Crests

Body Structure and Locomotion

The rest of Dilophosaurus's body was built for agility and speed, with a long, flexible neck supported by light, hollow vertebrae filled with air sacs - making it both strong and lightweight. Its body had 14 back vertebrae and a very long tail made of 45 vertebrae that likely helped with balance while running or turning. The arms were strong and muscular, ending in hands with four fingers, including a large claw on the innermost finger for grasping prey. Its shoulder blades were broad and distinctive, and the hind legs were long and powerful, built for fast movement, with large, three-toed feet sporting sharp claws. The pelvis was sturdy, and the legs were shaped for running, with the massive thigh bone (femur) being slightly longer than the lower leg bone (tibia), giving Dilophosaurus a characteristic, athletic dinosaur build.

The best current evidence suggests that Dilophosaurus was a fast, agile dinosaur. Its long, strong legs, lightweight skeleton, and stiffened tail would have made it an efficient runner, able to chase down prey. Its hands faced inward towards each other (not downwards), making them useful for grasping, but the animal's main contact with prey likely came from its jaws rather than its arms. While earlier suggestions imagined Dilophosaurus using its arms for slashing or even swimming, more recent work finds its hands best suited for seizing smaller prey or manipulating objects close to its chest.

Trackways, Behavior, and Social Life

Trackways and fossil "resting poses" from the Early Jurassic match what we know of Dilophosaurus, and while we can't be 100% certain, it's very likely that they were made by this dinosaur or a close relative. They indicate that Dilophosaurus could crouch similarly to modern birds, resting with its weight on its feet, metatarsals, and hips, while keeping its tail elevated. Its forelimbs were flexible enough for grasping and holding, but their range of motion suggests they were less important for locomotion or digging, and more for helping secure food or during displays. It may also have traveled in small groups, though definitive evidence for pack behavior is still debated and very hard to determine from the fossil record.

What Did it Eat?

Dilophosaurus was likely an opportunistic predator and scavenger, with a diet that included whatever prey was available. Its long, slender jaws and curved teeth were well-suited for grabbing and slicing smaller animals, and several features suggest it may have hunted fish as well. The tip of its snout was expanded into a "rosette" of interlocking teeth - similar to modern fish-eating crocodilians - which is ideal for catching slippery prey. Its nostrils were set farther back on the skull, possibly to help keep water out while fishing, and its strong, clawed arms could have helped snatch prey from the water. Although earlier researchers thought it had a weak bite and might have relied mostly on scavenging, more recent studies indicate Dilophosaurus had jaws strong enough to take on larger animals. Overall, Dilophosaurus probably ate anything it could catch or find, from small vertebrates and fish to the remains of larger dinosaurs.

Where it Lived: The Kayenta Formation

Dilophosaurus fossils are found in the Kayenta Formation, which consists of ancient riverbeds and sand dunes spread across parts of Arizona, Utah, Colorado, and New Mexico. The area was seasonally dry, with stretches of sandy desert and rivers bordered by conifer trees and other vegetation. Sometimes, sand dunes from the nearby Navajo desert would move into these river environments, resulting in a landscape with both wet and dry areas.

The Kayenta Formation contained a variety of animal and plant life. The rivers and lakes were home to bony fish, lungfish, freshwater clams, snails, salamanders, and frogs. On land, there were conifers and other plants, as well as turtles, lizards, early crocodile relatives, and small mammals. Dinosaurs were also present, including other theropods, early plant-eating dinosaurs such as Sarahsaurus and Scutellosaurus. This environment provided Dilophosaurus with several potential prey animals and a habitat that changed with the seasons.