How Scientists Determine Dinosaur Speed

Determining the speed of an animal extinct for millions of years is a complex challenge. Understanding locomotion is more than just satisfying curiosity; it helps reconstruct the behaviors and interactions that defined Mesozoic ecosystems. The speed of a predator and its prey reveals much about their survival strategies and the dynamic balance of their environment.

How Scientists Clock Dinosaurs

One of the most direct methods for estimating dinosaur speed comes from fossilized trackways. A series of preserved footprints reveals the stride length of the dinosaur that made them. Scientists use this measurement, along with the estimated hip height of the animal—often calculated by multiplying its footprint length by four—to determine its speed using formulas that provide an estimate of the animal’s pace at that specific moment.

These fossil trackways offer a snapshot of a dinosaur in motion. However, a limitation is that animals do not always travel at their maximum speed, especially on soft ground where tracks are more likely to fossilize. The fastest speeds calculated from these tracks, belonging to a medium-sized theropod, are around 27 miles per hour. Identifying the exact species that made the tracks can also be difficult.

To complement trackway data, researchers also employ biomechanical modeling. This approach uses physics and engineering to analyze how a dinosaur’s body moved. Scientists reconstruct the musculoskeletal system using fossilized bones, which show where muscles once attached. By comparing this anatomy with living relatives like birds and crocodiles, they can estimate muscle mass and body weight, which are then used in computer simulations to calculate potential speeds.

Speed Demons and Slowpokes of the Mesozoic

Among the fastest dinosaurs were the ornithomimids, or “ostrich mimics,” such as Gallimimus and Struthiomimus. These dinosaurs possessed long, slender legs and a lightweight build, suggesting they were highly adapted for running. Estimates based on their anatomy place their top speeds in the range of 30 to 40 miles per hour, making them some of the swiftest of their time.

In contrast were the giants and the heavily armored species. Large sauropods like Apatosaurus and Brachiosaurus, weighing many tons, were built for size, not speed. Their massive, pillar-like legs supported their weight, limiting them to a walking pace of around 5 to 10 miles per hour. Similarly, the ankylosaurs, covered in thick bony plates, were not built for swift movement as their defensive armor made speed unnecessary.

The speed of Tyrannosaurus rex remains a topic of active scientific discussion. Early portrayals showed it as a terrifyingly fast predator, but biomechanical studies have tempered this view. Some models suggest T. rex could not run at all, as the stress on its massive leg bones would have been too great. Instead, it may have been a brisk walker, capable of speeds around 10 to 15 miles per hour, a pace sufficient to hunt slower-moving herbivores.

Built for Speed (Or Not)

A dinosaur’s potential for speed was written in its skeleton. One indicator is the ratio of the lower leg bones (tibia and fibula) to the thigh bone (femur). Fast-running animals, both modern and extinct, often have lower leg segments that are significantly longer than their femurs. This adaptation increases stride length and efficiency.

This limb proportion is part of a suite of traits known as cursorial adaptations. Many swift dinosaurs, like the ornithomimids, also had a digitigrade stance, meaning they walked on their toes. This posture further lengthens the leg and allows for a more efficient, spring-like step. The overall build was also a factor; lighter skeletons belonged to agile runners, while massive frames were characteristic of slower animals.

The tail also played a part in locomotion for bipedal runners. It was not just a trailing appendage but a dynamic counterbalance. The tail shifted from side to side during movement, helping to maintain stability and allowing for quick turns, much like a cheetah uses its tail today.