Young tyrannosaurs hunted their own prey, and ate differently than adults. This has been concluded by an international team of paleontologists, after analyzing the remains of a juvenile specimen of Gorgosaurus libratus, a dinosaur from the tyrannosaur family, unearthed at the Dinosaur Park Formation site in Alberta, Canada.
The finding, published this Friday in Scientific Reports, establishes that young and adult specimens of these superpredators could coexist in the same environment without conflict, because they followed different diets. “This is possibly one of the reasons why tyrannosaurs were so successful in the last million years of the Cretaceous,” Jared Voris, a paleontologist at the University of Calgary and one of the authors of the work, defended at a press conference.
The hypothesis had been proposed previously because the physical characteristics of adults and young people in this family of dinosaurs were very different. While the former had enormous skulls and teeth the size of bananas capable of breaking bones, the latter were more graceful, with razor-like teeth and weak bites. However, there was no fossil evidence to confirm this idea, and other studies had proposed that the young fed on remains that the older ones did not want.
The discovery, for the first time, of a fossilized tyrannosaur specimen with its stomach contents almost intact has confirmed that the dietary patterns of adults and young people were different.
In the abdominal cavity of Gorgosaurus, where its stomach once was, scientists have found, also fossilized, the hindquarters of two small herbivores, less than a year old, which were devoured days apart. The prey, weighing between 9 and 12 kilograms, were too small to have interested an adult tyrannosaur.
The scientists' hypothesis is that the fossilized specimen, about five years old, hunted its prey on its own. Then he dismembered them and ingested only their hind legs, including the bones. This behavior, which according to the team of paleontologists is extendable to other species of tyrannosaurs, differs from that of adults, which consumed any part of their victim.
“The fact that the young Gorgosaurus ingested the same body parts of two individuals of the same species and of the same age in separate events suggests that it had a different diet than adults of the same species,” he develops in a press conference. François Therrien, a researcher at the Royal Tyrrell Museum in Alberta, Canada, who co-led the research.
According to the Canadian scientist, until the age of 11, tyrannosaurs were mesopredators, that is, they hunted small prey. From then on, they began to undergo a series of physical changes. Essentially their skulls grew, their teeth became more robust, and their bite began to gain strength. At the end of the process, the adult specimen was a superpredator capable of confronting and devouring the largest herbivores.
“The study provides the first direct evidence that tyrannosaurs occupied different ecological niches over the course of their lives,” says Voris, from the University of Calgary. “The environments that contained superpredators like Gorgosaurus did not have other species of mesopredatory dinosaurs,” concludes the expert. This limited the competition of the tyrannosaur family, and contributed to its success in the later years of the dinosaur era.
