Archaeologists in Canada have uncovered an exceptionally well-preserved fossil of a young tyrannosaur that contains the remains of the fearsome predator’s last meal. The fossil offers an unprecedented glimpse into the diet and behavior of juvenile tyrannosaurs as they matured into apex predators.
Chance Discovery in Alberta Badlands
The fossil was discovered by chance in 2021 when a team from the Royal Tyrrell Museum of Paleontology in Drumheller, Alberta was preparing to wrap up a dig in the badlands of the province.
As the crew was excavating the nearly complete skeleton of a young tyrannosaur known as a “Gorgosaurus libratus,” they noticed something unusual in the abdominal region – a large mass with visible bones. Further investigation revealed the mass to be the undigested remains of the Gorgosaurus’ last meal before it died.
“It was completely unexpected and one of the highlights of my career,” said lead paleontologist Caleb Brown in an interview. “Finding any dinosaur fossil with stomach contents is exceptionally rare.”
Surprise Contents: The Bones of Juvenile Herbivores
Analysis showed the abdominal mass contained bones from at least two different juvenile plant-eating dinosaurs that were only a few years old. This discovery contradicts the long-held belief that young tyrannosaurs only hunted small prey.
“It demonstrates that juveniles were capable of tackling quite large prey, even if it was young itself,” Brown said.
The meal remains point to the Gorgosaurus ambushing a herd of larger herbivorous dinos and managing to take down some juveniles despite its smaller size compared to an adult tyrannosaur.
While adult tyrannosaurs likely focused on hunting giant, full-grown dinosaurs, younger ones had to adapt different strategies to survive, often targeting juveniles and sick or weak adults.
|Estimated Age at Death
|Young long-necked herbivore
|Young horned dinosaur
Table showing details on the juvenile dinosaurs found in the Gorgosaurus’ stomach.
Implications for Understanding Tyrannosaur Behavior
The contents found inside the Gorgosaurus’ abdomen are groundbreaking as it represents the first direct evidence showing what juvenile tyrannosaurs were eating.
All previous assumptions about diets were based on bite marks on bones, coprolites (fossil feces), or speculation grounded in what modern-day relatives like crocodiles and Komodo dragons eat.
David Hone, an expert on dinosaur ecology at Queen Mary University of London not involved in the research, called the fossil “a once in a lifetime discovery.”
“This will vastly improve our understanding of how these mighty predators lived and grew into some of the largest carnivores to ever walk the Earth,” Hone said.
The fossilized stomach contents provide a snapshot into the everyday diet of juveniles transitioning to become deadly hunters of even giant prey as massive adults that measured over 12 meters long.
It also gives clues into how different tyrannosaur species potentially carved out ecological niches to avoid direct competition as juveniles and adults.
The Specimen: A Young Female Nicknamed “Darla”
The Gorgosaurus itself has been named “Darla” by the paleontology team. Analysis shows it was a late juvenile around 13 years of age based on growth ring counts in its bones. Darla stretched about 6 meters long and weighed over half a ton.
From scans and anatomical details of the well-preserved skull and skeleton, researchers confirmed Darla represents the first known female Gorgosaurus specimen found to date.
Darla’s incredible preservation allows tracing of injuries and signs of stress while alive. She appears to have suffered a fractured rib and toe infection in her last year but healed from the trauma.
“She was clearly a tough youngster,” Brown remarked. The infections may have slowed and weakened Darla enough to enable the juveniles she ambushed to inflict some fatal wounds in return during her last hunt.
Window Into The Past: Death by Drowning Enabled Unique Preservation
What led to the unprecedented preservation of Darla’s remains and stomach contents? The context of where and how she died provides critical clues.
It appears she either drowned in a flood or was swept far into a river channel after expiration. The lack of scavenging combined with thick, oxygen-free muds enabled natural mummification of her body’s soft tissues.
“Essentially she was pickled by the river sediment,” explained Jakob Vinther, a paleobiologist from the UK not involved with the finding. “For a short period, her body would have been like a floating bag of organs as decomposition gases built up, allowing the stomach sack and contents to hold together.”
Eventually Darla sank and was sealed under meters of mud minimally disturbed over epochs. Without oxygen, bacteria were unable to break down the remains leading to the incredibly rare degree of preservation witnessed.
Alberta: Prime Dinosaur Graveyard
The badlands of Alberta have become a world hotspot for dinosaur fossil discoveries due to the ideal preservation conditions explained by Darla’s story.
Rich sediment washed in by rivers and streams buried countless dinosaurs over 75 million years ago. The region was then uplifted over epochs, and erosion now constantly reveals ancient skeletons entombed within the exposed rock layers.
The dry climate and lack of vegetation cover aid fossil hunting and excavation compared to more tropical, forested dinosaur dig sites in the world. As a result, Alberta’s badlands rank among the planet’s richest sources of Late Cretaceous dinosaurs.
Future Research: More Surprises In Store?
While Darla’s remains answer many questions about tyrannosaurs, the fossil opens up whole new avenues for dinosaur research.
CT scans underway could potentially reveal gut contents from her intestines to see how quickly digestion occurred. Plant material swallowed accidentally with prey may offer insight into the landscape and vegetation at the time.
Chemical analysis looks promising to detect traces of organic compounds left from decayed muscle, skin, or organs leading to better understanding of what the internal anatomy and physiology was like.
Many more secrets are waiting to be uncovered from Darla’s unprecedented preservation researchers say. Her stomach contents represent just the first taste of what revelations may still lie in store from analyzing this remarkable fossil assemblage.
For now, Darla offers the world its first glimpse into the everyday diet of an adolescent tyrannosaur transforming into a huge predator – an iconic group of dinosaurs that continues to intrigue over 66 million years since they last walked the Earth.
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