Thanks to their reign of terror in “Jurassic Park,” the Velociraptor is an infamous predator from prehistoric times.
But the sickle-shaped killing machines familiar to moviegoers are far from scientific machines. It's not just that the fictional machine lacks feathers. The real Velociraptor was as big as a Labrador Retriever and much smaller than the human-sized hunter depicted in the film series.
Nonetheless, some raptors have achieved impressive sizes. And a team of paleontologists say they may have identified a new megaraptor based on a set of fossilized footprints discovered in China. In a paper published this week in the journal iScience, researchers estimated the footprints left by the dinosaur, one of the largest raptors known to science.
The raptor's tracks are part of larger dinosaur tracks discovered in southeastern China in 2020. About 90 million years ago, during the late Cretaceous period, the region was a mud river plain home to all kinds of dinosaurs, including long-necked sauropods and ducks. – Claimed herbivore. These dinosaur dwellers left muddy footprints as they stomped around. Some of them have been preserved for tens of millions of years.
About 240 dinosaur footprints were discovered in Longxiang. The track site is roughly the size of a hockey rink. Some of the footprints are oddly shaped, with only two toes having preserved imprints.
“If you look at a dinosaur footprint with only two toes, you can play the game of Cinderella slippers and find a foot that matches it,” said Stephen Brusatte, a paleontologist at the University of Edinburgh who was not involved in the study. “The only dinosaurs that walked on two toes were ‘raptors’ like Velociraptor and their close relatives.”
Raptors leave strange marks because their inner toes are off the ground. This prevented the overly large, recurved claws on the toes from dragging on the ground and becoming dull.
Some of Longxiang's two-toed footprints appear to have been left by smaller dinosaurs the size of Velociraptor. But researchers discovered a set of five footprints over 13 inches long, making them the largest raptor footprints in the fossil record. Based on the size of the footprints, the dinosaur that left them was approximately 5 feet tall and 15 feet long, putting it near the largest known raptors, including Utahraptor.
The unique footprints inspired paleontologists to name the new raptor Fujianipus (meaning “foot of Fujian”) yingliani. Finding fossilized bones could help researchers further refine the animal's appearance, but the proportions of its two toes suggest Fujianipus is a trodontid, a type of bird-like raptor that lived in Asia and North America during the Cretaceous period. It is likely a troodontid).
Raptors are often depicted as fast-paced predators. But footprints alone don't tell us how fast Fujianipus moved, according to W. Scott Persons, a paleontologist at the University of South Carolina in Charleston and a co-author of the new paper.
He thinks the raptor may have been watching his steps as he crossed the muddy riverbed. “When you walk on mud, you will move very carefully to avoid slipping,” Dr. Persons said. “It was probably the same for our raptors.”
Without fossilized leg bones, researchers cannot estimate Fujianipus' speed. However, members of the trodontid group to which this dinosaur may have belonged “had the longest legs of all raptors,” says Dr Persson, suggesting Fujianipus was probably a fast predator.
Speed would have been useful in the Late Cretaceous. This was a period in which older lineages of predatory dinosaurs gradually gave way to upcoming groups of carnivorous dinosaurs, such as raptors and the languid tyrannosaurs.
“During this period, two iconic dinosaur groups, tyrannosaurs and raptors, both appear to have been competing for the mid-sized predator crown,” Dr. Brusatte said.
Tyrannosaurus went on to grow into behemoths like Tyrannosaurus Rex, but raptors largely remained small. Giants like Fujianipus and Utahraptor are outliers.
“Raptors experimented with large body sizes, but unlike many other groups of carnivorous dinosaurs, they did not stick to that size,” Dr. Persons said. “Raptors seem to be much better at being small to medium-sized carnivores than they are at being large.”