More than a hundred million years ago, a pair of theropods—three-toed, bipedal dinosaurs—sprinted across a lakebed in modern-day northern Spain. They left behind a collection of footprints, which now reveal that they could reach a speed of 27.7 miles per hour, one of the fastest speeds ever calculated for theropods, Mindy Weisberger reports for Live Science.
The study, which published last week in Scientific Reports, offers new insights into theropod behavior.
"The image that we have of dinosaurs 30 years ago or so is changing," lead author Pablo Navarro-Lorbés, a paleontologist at the University of La Rioja in Spain, tells Aylin Woodward for the Wall Street Journal. "In the past we thought that they were lumbering animals not well adapted to the environment. Now we see that some are perfectly adapted to hunting and running."
The prints were discovered in La Rioja, Spain, around 35 years ago, but scientists didn't fully excavate all the tracks until more recently. They found a set of five footprints belonging to one dinosaur, and seven belonging to the other. By measuring the footprints and the length between them, the team estimated how fast the dinos dashed, Carissa Wong reports for New Scientist.
One of the printmakers was smaller than the other and ran between 14 and 21 miles per hour, slower than the larger one who reached nearly 28 miles per hour. Though the team hasn't determined exactly what species the theropods belonged to, they estimated that they were around six feet tall and about 16 feet long. The team hypothesized that they were either spinosaurids, a species that sport a spiny back, or carcharodontosaurids, which the infamous T. rex belongs to, Megan Marples reports for CNN.
Given that theropods are mostly carnivorous, these two dinosaurs may have evolved a quick pace and sharp agility in order to capture prey, Isaac Schultz reports for Gizmodo.
As speedy as these theropods were, they weren't quite fast enough to claim the title for fastest theropod. Tracks found in Utah suggest that those printmakers reached speeds over 30 miles per hour, Emma H. Tobin reports for the Associated Press (AP). (For comparison, white-tailed deer can sprint up to 30 miles per hour, and Jamaican sprinter Usain Bolt's top speed is about 27.33 miles per hour.)
Though these theropods don't win the first-place trophy, their tracks provide important insights into theropod behavior and physiology. The results of this study also match previous estimates for theropod speed, which were calculated using the animals' bones, Navarro‐Lorbés tells Live Science.
"Fast-running theropod tracks are scarce in the fossil record," Navarro‐Lorbés says. "Being able to study them and confirm some other studies made from different approaches are great news for us."