A fossilized dinosaur from about 75 million years ago had its final meal well-preserved in its stomach, revealing surprising details about its diet.
The young Gorgosaurus libratus, a type of tyrannosaur, was found with the hind legs of small bird-like dinosaurs in its stomach, according to researchers at the University of Calgary.
Tyrannosaurs, which include Gorgosaurus and the more famous Tyrannosaurus, were some of the most formidable predators of their time. Evidence suggests that older tyrannosaurs typically ate large herbivores, researchers said.
However, the latest discovery suggests that the species’ diets changed as they grew, per research published in the journal Science Advances.
” This is the first instance that stomach contents so well preserved have been discovered inside the skeletons of large species of dinosaurs,” Darla Zelenitsky ,, the coauthor of the research.
The creature weighed over 700 pounds — only around 10% of the mass of an adult– and was believed to have died young, between the ages of five and seven. First discovered in 2009, Dinosaur Provincial Park in Canada.
Museum staff first spotted toe bones in the stomach area of the dinosaur.
Researchers determined that these were the remains of Citipes, small turkey-sized dinosaurs.
“The rock within the ribcage was removed to expose what was hidden inside. According to Francois Therrien, coauthor of the study, “the complete hindlegs of two young dinosaurs under one year were found in its stomach.”
It appeared that there were two different sets of legs eaten at different times, which was determined by the different levels of digestion.
In the case of dinosaurs, the hind legs may have been chosen because it was the most meaty part of their body.
“It is well known that the tyrannosaurs grew from slim to robust dinosaurs that crushed bones. We know this was due to their feeding habits,” Zelenitsky explained.
“They seem to have evolved from catching prey as small as Citipes as teens to capturing megaherbivores as adults.
The discovery shows that juvenile tyrannosaurs, who had narrow skulls and blade-like teeth, were better suited to eat small prey, while adult tyrannosaurs’ large skulls and strong teeth meant they could eat much larger prey.