Thanks to their reign of terror in ‘Jurassic Park,’ Velociraptors are notorious prehistoric predators.
However, the sickle-claw killing machines that moviegoers are familiar with are a far cry from their scientific counterparts — and not just because the fictional machines have no springs. In real life, Velociraptors were the size of a Labrador retriever and were much smaller than the human-sized hunters portrayed in the film series.
Still, some birds of prey reached impressive sizes. And a team of paleontologists said it may have identified a new megaraptor based on a series of fossilized footprints 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 be among the largest birds of prey known to science.
The raptor’s footprints are part of a larger dinosaur track discovered in southeastern China in 2020. During the Late Cretaceous period, about 90 million years ago, the area was a muddy river plain that was home to all kinds of dinosaurs, including long-necked sauropods and ducks. -billed herbivores. As these dinosaur dwellers stomped around, they left behind muddy footprints, some of which have been preserved for tens of millions of years.
About 240 dinosaur tracks have been discovered in Longxiang, on the track, which is about the size of a hockey rink. A few of the footprints are oddly shaped, with preserved prints showing only two toes.
“If you see dinosaur footprints with only two toes, you can play the Cinderella slipper game and look for feet that match,” says Stephen Brusatte, a paleontologist at the University of Edinburgh who was not involved in the new study. “The only dinosaurs that walked on two toes were ‘birds of prey’ like Velociraptor and their close relatives.”
Birds of prey left such strange prints because their inner toes were held off the ground. This prevented the oversized, recurved claw of the toe from dragging on the ground and becoming blunt.
Several of Longxiang’s two-toed tracks appear to have been left by a small dinosaur about the size of a velociraptor. But the researchers found a series of five tracks that are more than 30 centimeters long, making them the largest raptor tracks in the fossil record. Judging by the size of the tracks, the dinosaur that left them was about five feet long and five feet tall, putting it close to the largest known birds of prey, including the Utahraptor.
The striking footprints inspired paleontologists to name the new bird of prey Fujianipus (meaning ‘the foot of Fujian’) yingliangi. Although finding fossilized bones would help researchers further elaborate on what the animal looked like, the proportions of its two toes make it likely that Fujianipus was a troodontid, a type of bird-like bird of prey that lived in Asia and North America during the Cretaceous Period.
Birds of prey are often depicted as fast predators. But footprints alone can’t give a sense of how fast Fujianipus moved, said W. Scott Persons, a paleontologist at the College of Charleston in South Carolina and co-author of the new paper.
He thinks the bird of prey probably watched his steps as he crossed the muddy riverbed. “When you walk in mud, you have to move very carefully to avoid slipping,” said Dr. Persons. “That was probably also the case for our bird of prey.”
Without fossilized leg bones, the researchers cannot estimate the speed of Fujianipus. But members of the troodontid group, to which it probably belonged, were “among the longest of all birds of prey,” 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 lineages of predatory dinosaurs gradually gave way to emerging groups of carnivores such as raptors and lanky tyrannosaurs.
“During this time, it appears that these two iconic groups of dinosaurs, the tyrannosaurs and the raptors, were both competing for the crown of medium-sized predators,” said Dr. Brusatte.
While tyrannosaurs would continue to grow into behemoths like Tyrannosaurus rex, birds of prey remained largely small. Giants like Fujianipus and Utahraptor are outliers.
“Raptors experimented with large body sizes, but unlike many other groups of carnivorous dinosaurs, they didn’t stick to it,” said Dr. Persons. “It appears that birds of prey were much better small and medium carnivores than large carnivores.”