Certain dinosaurs could reach speeds of up to 45 kilometers per hour. This is what paleontologists conclude from the analysis of footprints in the northern Spanish region of La Rioja. The tracks are from theropods, mostly carnivorous dinosaurs, the most famous of which is the species Tyrannosaurus rex.
Several decades ago, researchers discovered hundreds of dinosaur footprints near the town of Igea. The team led by Pablo Navarro-Lorbés from the University of Rioja in Logroño has now analyzed two print series, each consisting of around half a dozen tracks. The individual imprints are each about 30 centimeters long and are so similar that the researchers assume that they come from related species.
Basically, the speed of extinct animals can be determined in two ways, the authors write:
– through anatomy-based biomechanical models
– by analyzing the footprints. For this purpose, the height of the hips is calculated from the length of an imprint and set in relation to the step length.
The distance between the individual tracks in the two imprint series is around 2.65 and 2.80 meters, so a sequence of steps measures around twice as much. The hip heights of the animals were therefore around 1.30 and 1.15 meters.
The researchers calculated from this that the average speed of one animal was 23 to 37 kilometers per hour, that of the other even 32 to 45 kilometers per hour. "These speeds are among the fastest that have been determined in dinosaurs through track analysis," they write in the journal Scientific Reports.
However, the record holder for theropods examined by trace analysis is a specimen whose footprints were analyzed in the US state of Utah. It came to almost 50 kilometers per hour, as another research team reported earlier this year.
Another group had determined an even higher speed using biomechanical models: According to this, the roughly one meter small Compsognathus reached a - theoretical - speed of 65 kilometers per hour, as researchers reported in 2007 in the "Proceedings B" of the British Royal Society. According to this analysis, the Tyrannosaurus rex ran up to 29 kilometers per hour. At least human professional sprinters could have outrun him with it. Usain Bolt achieved top speeds of almost 45 kilometers per hour in his world record.
The Spanish researchers do not know which types of dinosaurs left their mark in the Rioja in the early Cretaceous period, i.e. around 150 to 100 million years ago. But they must have been very agile theropods of medium size, they write.
This article was first published in December 2021.