Three-toed, meat-eating dinosaurs may have sprinted as fast as a car cruising through city streets, according to a new study. This discovery comes from the analysis of the footprints left by these theropods as they scrambled over the spongy mud of the lake bed tens of millions of years ago.
Two sets of fossilized footprints at a site in La Rioja, Spain, show the creators of the tracks galloped at speeds of up to 27.7 mph (44.6 km / h), reaching “some of the highest speeds ever. calculated for theropod tracks ”. according to the new study.
According to the analysis of the leads by the researchers, a dinosaur sped up steadily and steadily as he ran, while the other quickly changed his speed while still moving. Together, these two sets of prints from the first part of the Cretaceous period (145 to 66 million years ago) provide a unique insight into the mobility and behavior of dinosaurs.
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Paleontologists Use Several Methods to Calculate Running Speeds in Extinct Dinosaurs, said Pablo Navarro ‐ Lorbés, researcher at the University of La Rioja in Logroño, Spain and lead author of the new study. One method builds biomechanical models based on the bones and proportions of dinosaur limbs, “and the other main one is estimating speed from the tracks,” Navarro-Lorbés told Live Science in an email. .
A set of tracks from La Rioja, dubbed La Torre 6A-14, preserves five three-finger footprints that each measured approximately 12.9 inches (32.8 centimeters) long and 11.9 inches (30.2 cm) wide. The other track, La Torre 6B-1, features seven three-fingerprints that were a bit smaller, measuring 11.4 inches (28.9 cm) long and 10.6 inches (26.9 cm) wide . Based on the size of the footprints, the hip height of theropods would have been between 1.1 and 1.4 meters (4 to 5 feet), so the animals would have been approximately 2 m (7 feet) high and were approximately 13 to 16 feet long. (4 to 5 m) “from the muzzle to the end of the tail,” said Navarro-Lorbés.
While it is not possible to say what genus of theropod traced the tracks, the similarities between the footprints suggested that the two dinosaurs belonged to the same taxonomic group, were not avian – not one of the directly related lineages. to modern birds – and were “very agile,” according to the study.
To calculate the running speeds of theropods, the researchers used a formula that incorporated the height of the hips and the stride length of the dinosaurs. This allowed them not only to calculate the speed of the animals with each step, but also to detect variations in speed “like acceleration or deceleration”, explained Navarro-Lorbés. They found that the dinosaur that built runway 6A-14 hit just over 23 mph (37 km / h), while the faster 6B-1 dinosaur took the lead with a top speed up close. of 28 mph (45 km / h).
By comparison, the fastest speed ever recorded on a human runner is 27.5 mph (44.3 km / h), which was achieved very briefly by famous Jamaican sprinter Usain Bolt in 2009, according to the New York Times.
But while Bolt’s racing prowess has been well documented, extinct dinosaurs aren’t so lucky. Tracks that can reveal their running speeds are exceptionally rare, so these footprints from northern Spain provided a unique opportunity for researchers to corroborate theropod speed estimates that had previously been produced by other scientists who analyzed them. animal bones, said Navarro-Lorbés.
“Traces of rapid theropods are rare in the fossil record,” said Navarro-Lorbés. “Being able to study them and confirm other studies done using different approaches is great news for us.”
The results were published online Thursday, December 9 in the journal Nature.
Originally posted on Live Science.