Thanks to their reign of terror in Jurassic Park, Velociraptors are notorious prehistoric predators.
However, the sickle-claw killing machines familiar to moviegoers are a far cry from their sci-fi counterparts – and not just because those fictional ones lack feathers. In real life, Velociraptors topped out at the size of a Labrador retriever and were much smaller than the human-sized hunters portrayed in the film series.
However, some predators reached impressive proportions. And a team of paleontologists said they may have identified a new megaraptor based on a set of fossilized tracks found in China. In a paper published this week in the journal iScience, researchers estimated that the tracks were left by a dinosaur that would have been among the largest predators known to science.
The raptor tracks are part of a larger dinosaur track discovered in southeast China in 2020. During the Late Cretaceous period, about 90 million years ago, the area was a muddy river plain, home to all kinds of dinosaurs , including long-necked sauropods and duck-billed herbivores. As these dino-dwellers stampeded their feet, they left footprints in the mud—some of which have been preserved for tens of millions of years.
About 240 dinosaur tracks have been discovered in Longxiang, at the site of the track, which is roughly the size of a hockey rink. Some of the footprints are oddly shaped, with preserved footprints featuring only two fingers.
“When you see dinosaur footprints with only two toes, you can play the Cinderella slipper game and look for matching feet,” said Stephen Brusatte, a paleontologist at the University of Edinburgh who was not involved in the study. young. “The only two-toed dinosaurs were ‘raptors’ like Velociraptor and their close relatives.”
Raptors left such strange tracks because their inner toes were kept off the ground. This prevented the oversized, bent toe claws from dragging on the ground and becoming dull.
Some of Longxiang’s two toe prints appear to have been left by a small velociraptor-sized dinosaur. But the researchers found a set of five tracks that are more than 13 inches long, making them the largest predator tracks in the fossil record. Based on the size of the tracks, the dinosaur that left them stood roughly 5 meters tall and 15 feet tall, putting it in the neighborhood of the largest known raptors, including Utahraptor.
Its distinctive footprints inspired paleontologists to name the new predator Fujianipus (meaning “foot of Fujian”) yingliangi. While finding fossilized bones would help researchers further understand what the animal looked like, the size of its two toes makes it possible that Fujianipus was a troodontid, a type of bird raptor that inhabited Asia and North America during the Cretaceous period.
Raptors are often described as fast-paced predators. But footprints alone cannot provide a sense of how fast Fujianipus moved, according to W. Scott Persons, a paleontologist at the College of Charleston in South Carolina and co-author of the new paper.
He thinks the predator was most likely watching his step as he crossed the muddy river bed. “When you walk through the mud, you move very carefully to avoid slipping,” said Dr. Persons. “That was probably the case for our predator as well.”
Without fossilized leg bones, researchers cannot estimate the speed of Fujianipus. But members of the troodontid group, to which it probably belonged, were “among the most legged of all predators,” said Dr. Persons, suggesting that Fujianipus was probably a fast predator.
Speed would have come in handy during the late Cretaceous, a period when older lines of predatory dinosaurs were gradually giving way to growing groups of carnivores such as raptors and lean tyrannosaurs.
“During this time, it seems like these two iconic groups of dinosaurs, the tyrannosaurs and the raptors, were both competing for that middle predator crown,” said Dr. Brusatte.
While tyrannosaurs would go on to grow into giants like Tyrannosaurus rex, predators mostly stayed small. Giants like Fujianipus and Utahraptor are incredible.
“Raptors experimented with large body sizes, but, unlike many other groups of carnivorous dinosaurs, they didn’t stick to it,” said Dr. Persons. “Raptors appear to have been much better at being small and medium-sized carnivores than large ones.”