Weighing more than 5000 kg, with knife-like teeth and tiny toddler arms, T-rex was the top dog in the late Cretaceous. A study by Pasha Bijlert et al. has estimated the Preferred Walking Speed (PWS) of Tyrannosaurus rex based on an observation made on extant animals. According to the authors, many animals, when they have no external motivations (like chasing prey or escaping predators) move at an optimal speed which allows the walking frequency to match the ‘natural frequency’ of their limbs. This increases resonance and minimizes energy expenditure.
The limbs most important to the T-rex’s walk were the hind legs and the tail. Earlier studies on T-rex locomotion, according to authors, focused entirely on the hind legs, ignoring the influence of the tail. This study, however, looked more closely at the role of the tail and the caudal interspinous ligaments that support the tail.
To do this, the researchers made a 3D reconstruction of an adult T-rex skeleton named “Trix” from the Naturalis Biodiversity Center in Leiden, The Netherlands. The tail was modelled as a mass-spring system.
“Elastic energy storage in these ligaments improved locomotor efficiency, and like a mass on a spring, the tail would have oscillated at the step frequency.”
From the model, the researchers estimated the preferred walking speed of T-rex to be 1.28 m/s. For comparison, the walking speed of the average human is 1.3 – 1.4 m/s. Some scenes featuring T-rex from Jurassic Park might seem exaggerated to you after reading this, but remember, this is the speed of a T-rex on an evening stroll by the beach. Who knows how fast baby-hands was when chasing prey?
Read more about the study here.
