Dilophosaurus wetherilli, a theropod that roamed North America approximately 183 million years ago, was among the most striking predators of the early Jurassic period. Its fame largely stems from the distinctive pair of bony, semicircular crests that adorned its skull. The first skeletons were discovered in northern Arizona in 1940, establishing it as the largest known land animal in the region at the time. Despite its status as a significant predator, the public perception of its true dimensions is often skewed by fictional portrayals.
Scientific Estimates of Body Size
Modern paleontological analysis reveals Dilophosaurus to be a significantly larger animal than many assume, classifying it as a medium-sized theropod when compared to giants like Tyrannosaurus. The maximum estimated length for a fully grown individual is approximately 23 feet (7 meters).
The estimated body mass places the largest specimens at around 800 to 1,000 pounds (360 to 450 kilograms), which is roughly the weight of a large modern polar bear. While lightly built for a theropod of its length, this mass made it a formidable predator in its ecosystem. The standing hip height of the animal is estimated to have been between 5.7 and 7.4 feet (1.75 to 2.25 meters).
Determining Size from the Fossil Record
Paleontologists determine the dimensions of Dilophosaurus by examining incomplete fossil remains. The process relies heavily on measuring key skeletal elements, such as the length and circumference of the femur (thigh bone), and then using allometric scaling. Allometric scaling compares the proportions of the known bones to those of complete skeletons of closely related theropods to extrapolate the total body length and mass.
The initial discovery was actually a subadult, which initially led to slightly smaller size estimations. This specimen was approximately 19 feet 9.5 inches (6.03 meters) long and weighed about 624 pounds (283 kilograms). Subsequent, larger finds, such as UCMP 77270, which included vertebrae 18% longer than the holotype, have helped refine the maximum size estimates to the larger 23-foot figure.
Comparing the Real Dilophosaurus to Movie Depictions
The real Dilophosaurus stood in stark contrast to the small, frilled creature depicted in the 1993 film Jurassic Park. The movie version was shown to be roughly human-height, standing only about 4 feet (1.2 meters) tall and around 8 to 10 feet long. Scientifically, this size is closer to that of a juvenile or a much smaller theropod.
The actual animal was significantly larger. The fictionalized version was intentionally scaled down for the film, primarily to prevent it from overshadowing the Velociraptor as the main smaller predator. While the movie also added fictional features like a venom-spitting ability and a retractable neck frill, the most significant scientific inaccuracy remains the animal’s drastically reduced size.