Theropods were mostly carnivores and walked on two legs. Spanish researchers are now using the footprints to calculate the speed at which these primitive lizards can run.
Some dinosaurs could reach speeds of up to 45 kilometers per hour. This is what paleontologists have concluded from the analysis of footprints in the northern Spanish region of La Rioja. Traces come from theropods, especially carnivorous dinosaurs, the most famous representative of which is the type Tyrannosaurus rex.
A few decades ago, researchers discovered hundreds of dinosaur footprints near the town of Igea. The team led by Pablo Navarro-Lorpis of the University of Rioja in Logroño analyzed two series of publications, each consisting of about six tracks. The individual prints are about 30 cm long and are so similar that researchers hypothesize that they come from related species.
up to 45 kilometers per hour
In principle, the speed of extinct animals can be determined in two ways, the authors write: either through anatomical-based biomechanical models or through analysis of footprints. For this purpose, the hip height is calculated from the impression length and is set in relation to the stride length.
The distance between the individual tracks in the two series of prints is about 2.65 and 2.80 metres, so the series of steps measures twice that. Accordingly, the thigh heights of the animals were about 1.30 and 1.15 meters.
From this, the researchers calculated that the average speed of one animal was 23 to 37 kilometers per hour, and the average speed of the other animal was 32 to 45 kilometers per hour. “These speeds are among the fastest so far identified in dinosaurs through impact analysis,” they wrote in Scientific Reports.
For comparison: the cheetah is the fastest mammal in the country with a maximum speed of 120 kilometers per hour. The largest ostriches can run at speeds of up to 70 km / h.
Tyrannosaurus Rex was slower
However, the record holder among theropods examined by tracer analysis is a sample whose prints were analyzed in the US state of Utah. It hit nearly 50 kilometers per hour, another research team reported earlier this year.
Another group determined a higher speed using biomechanical models: Accordingly, the tiny Compsognathus of about one meter in size reached a theoretical speed of 65 kilometers per hour, researchers reported in 2007 in “Proceedings B” of the British Royal Society. According to this analysis, Tyrannosaurus Rex ran at a distance of up to 29 kilometers per hour.
Spanish researchers do not know what kinds of dinosaurs left their trails in the Rioja River in the early Cretaceous period, about 150 to 100 million years ago. But they write that they must have been medium-legged and very graceful.