About 75.3 million years ago, a dinosaur swallowed the Cretaceous equivalent of a turkey drumstick. It would be the last feast for the Predators.
Within days of eating its butt, the dinosaur, a 5.5-foot waist-high juvenile Gorgosaurus, died in a river. Through geological luck, sediment quickly covered most of the carcass, protecting the dinosaur and its dinner from decay.
The fossil, published Friday in the journal Science Advances, is the first Tyrannosaurus skeleton ever to have internally preserved stomach contents, providing a detailed snapshot of feeding behavior. The fossil also preserved Gorgosaurus’ skull, pelvis, and most of the left side of its body.
Although Gorgosaurus was an ancestral relative of Tyrannosaurus, this fossil contains no trace of the large herbivores that adult Tyrannosaurus would have eaten. Instead, this Gorgosaurus tore off the hind legs of her two small feathered dinosaurs. Researchers say the fossil provides the first direct evidence that tyrannosaurs changed their diet as they aged, as paleontologists had predicted from existing fossil evidence. claims.
Francois Therrien, curator of dinosaur paleoecology at the Royal Tyrrell Museum in Drumheller, Alberta, said: “This specimen shows that young tyrannosaurs not only ate different animals than adults, but also attacked and dissected different animals. We have obtained physical evidence that this occurred.” , and study author.
Coprolites (fossilized poop), teeth and bones damaged by stomach acid that have been discovered so far suggest that adult Tyrannosaurus ate large plant-eating dinosaurs such as Triceratops with a delicious bone-crunching experience. It shows. But before taking down the giant herbivore, Tyrannosaurus had to grow larger, with its skull and teeth wide and strong enough to produce one of nature’s most powerful bites.
However, juvenile Tyrannosaurus had a slender skull, narrow jaws, blade-like teeth, and long legs. Paleontologists interpret these features as signs that young tyrannosaurs must have been agile, an idea supported by new fossils.
“I jokingly call them the ballerinas of destiny. They run fast, spin quickly, and can chase down small, fast-running prey,” said a researcher at the University of Maryland, who was not involved in the study. said paleontologist Tom Holtz. .
Tyrannosaurus’ ability to act as a nimble medium-sized predator in its infancy before growing into an adult apex predator may have pushed out other predatory dinosaurs and given the group an evolutionary advantage. . The superior abilities of young tyrannosaurs are a strange feature of the North American fossil record of the Late Cretaceous, a “missing intermediate” predator between heavy adult tyrannosaurs and herds of human-sized dinosaurs. You might even be able to explain the size.
“The logic is that these juveniles were filling a gap for meso-sized predators,” says Darla Zelenitsky, a paleontologist at the University of Calgary and an author on the study. “They were the coyotes of the Cretaceous period.”
The Gorgosaurus specimen was discovered in August 2008 by Royal Tyrrell Museum technician Darren Tanke. Weathering had exposed ribs on a hillside at Alberta Dinosaur Park. However, this lucky discovery occurred during his last 45 minutes of the museum’s 2008 field season, and Gorgosaurus’ recovery was complicated. Tanke acquired it in the museum in March 2010.
Tanke then decided to dig deeper into the animal’s ribcage, removing excess rock from the fossil. To his surprise, he found several toe bones too small to belong to a Gorgosaurus, within a distinctive area that was later determined to be the contents of the Gorgosaurus’s stomach.
“This is probably the discovery of my career,” Tanke said, reflecting on the more than 11,000 fossils he collected for the museum. “I don’t think we’ll ever be able to top this.”
The contents of the stomach consist of the hind limbs and partial tail of a shrunken, cassowary-like beaked dinosaur known as Citypes. The two Citypes were each less than a year old when they were eaten, and judging by the degree of acid wear on their bones, Gorgosaurus must have eaten them in the last weeks of their lives, one a few days before the other. It is thought that Despite being stewed in Gorgosaurus’ stomach juices, Sitipes’ bones are extremely well preserved, making them the most complete fossils of the animal ever discovered.
This Gorgosaurus probably hunted small animals for several years before moving on to larger prey. In 2021, a research team including Therrien and Zelenitsky found that Gorgosaurus did not develop stronger bite forces and was unable to take on larger herbivores until it was 11 years old. The bones of this dinosaur indicate that it died between the ages of 5 and 7.
Although this Gorgosaurus was never part of the adult dinner table, Tellian believes there is little doubt that it ate well.
“Everyone loves drumsticks,” he said.