Canadian paleontologists have discovered the skeleton of a 75-million-year-old juvenile tyrannosaurid dinosaur. Gorgosaurus libratus Along with the remains of two young small dinosaurs. Citypes Elegance In its abdominal cavity.
Tyrannosauridae were a group of carnivorous dinosaurs that dominated the ecosystems of Asia and North America near the end of the Cretaceous period, 80 to 66 million years ago.
It is one of the largest terrestrial predators to have ever existed, growing from a few meters long hatchling to several tons (9-12 meters long, 2,000-6,000 kg). .
Juveniles were lithe with narrow skulls, blade-like teeth, and elongated hind legs, while adults were sturdy with huge skulls and large, unruly teeth that could cause bone-crushing bites. there was.
These changes suggest that the diet of tyrannosaurids has changed significantly, with juveniles and adults occupying different ecological niches.
Fossil evidence suggests that dinosaur megaherbivores (i.e., species with adult body weights greater than 1,000 kg, including ceratopsians, giant ornithomimosaurs, hadrosaurs, and sauropods) were common prey for large tyrannosaurids. It is clear that the diet was simply one that allowed them to develop the necessary adaptations and occlusal force. When an individual reaches the developmental stage of late boyhood or early subadulthood.
“Unfortunately, little fossil evidence is known about the diet of young tyrannosaurs, limiting our understanding of ontogenetic dietary changes in these iconic predators,” said lead author. said Dr François Therrien, a paleontologist at the Royal Tyrrell Museum, and his colleagues.
In their study, the authors examined well-preserved specimens. Gorgosaurus libratus Found in state dinosaur park in Alberta, Canada.
“Gorgosaurus libratus was a tyrannosaurid that lived 75 million years ago, or millions of years ago. tyrannosaurus rex – present-day southern Alberta,” they said.
“This person’s age at the time of death is estimated to be between 5 and 7 years old.”
“With an estimated weight of 335 kg based on the length of the femur (femur), this juvenile would have weighed less than 13% of the adult’s body weight.”
Researchers discovered the partial remains of two small dinosaurs inside their stomachs. Gorgosaurus libratus Specimen.
“Before this carnivorous dinosaur died, it butchered two young bird-like herbivorous dinosaurs of this species.” Citypes Elegance,” they said.
“Rather than swallowing its prey whole, young tyrannosaurs only ate the hind limbs (the fleshiest part of the body).”
“The prey is a dinosaur of the family Caenagnatidae, oviraptor From Asia. ”
Further study of the fossilized bones showed that both bones were present. Citypes Elegance A person died within the first year of life at the time of death.
“Rocks within the thorax were removed to expose what was hidden inside. Complete hind limbs of two baby dinosaurs, both less than a year old, were present in their stomachs. ” Dr. Therian said.
Because the two elements are at different stages of digestion, scientists were able to conclude that: Gorgosaurus libratusStomach contents represent two different meals taken hours or days apart.
The presence of two dinosaurs of the same species and age ingested at different times in the stomach contents suggests that juvenile Caenagnathidae were one of the preferred prey of juvenile gorgosaurs. It suggests possibility.
This specimen provides the first direct evidence that young gorgosaurs had a different diet than adult gorgosaurs.
Adult gorgosaurs are known to have hunted large herbivorous dinosaurs such as ceratopsians and hadrosaurs, based on teeth marks left on their bones.
Adult gorgosaurs used their huge skulls and large teeth to capture large prey, biting into bones and scraping flesh from carcasses.
However, young Gorgosaurus were not created to hunt such large prey. Juveniles were lean, with narrow skulls, blade-like teeth, and long, slender hind legs. They were ideally suited for capturing and butchering small, young prey.
Evidence suggests that Tyrannosaurus occupied different ecological niches throughout its life.
As young tyrannosaurs grew and matured, they likely transitioned from hunting smaller, younger dinosaurs to preying on larger herbivores.
This change in diet likely began around the age of 11, when Tyrannosaurus’ skull and teeth began to become stronger.
“It is well known that tyrannosaurs underwent a drastic change during their growth process, from slender bodies to powerful, bone-crushing dinosaurs, and we now know that this change was related to their feeding behavior. co-author Dr. Darla Zelenitsky of the University of Calgary said. of research.
“It’s like they just left hunting their prey.” Citypes Elegance From hunting giant herbivorous dinosaurs as teenagers (just a fraction of your body size) to as adults (same size or larger). ”
team’s paper It was published in the magazine scientific progress.
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François Therian other. 2023. Highly preserved stomach contents of a young tyrannosaurid reveal ontogenetic dietary changes in this iconic extinct predator. scientific progress 9(49); doi: 10.1126/sciadv.adi0505