Fossilized Stomach Reveals What Young Tyrannosaurs Ate

Paleontologists in Canada have made a new discovery concerning dinosaurs. They found a 75-million-year-old baby dinosaur skeleton belonging to the Gorgosaurus libratus species. What makes this finding so important is that its stomach contained the remains of two young Citipes elegans dinosaurs.

The Gorgosaurus libratus is a type of carnivorous dinosaur, and it was part of a group called tyrannosaurids. These dinosaurs were especially common in Asia and North America about sixty-six to eighty million years ago until the end of the Cretaceous period.

Tyrannosaurids were not small creatures. They were some of the biggest predators to ever walk the planet. Starting as tiny babies just a few meters long, they grew into enormous beings, reaching sizes of nine to twelve meters and weighing two to six thousand kilograms during their lifetime, according to Sci.News.

Tyrannosaurids experienced a major dietary change

When tyrannosaurids were young, they had slender bodies, narrow skulls, sharp teeth like blades, and long, slim hind limbs. However, as they matured, they became sturdier with large skulls and thick, powerful teeth capable of bone-crushing bites.

These transformations indicate that tyrannosaurids went through a significant change in their diet. It seems they were assigned different roles in their environments throughout their lifetime. This included a transition in their specific natural biological responsibilities.

The researchers were quite interested to learn more about what young tyrannosaurs were eating, as they suspected it was different from what they ate as adults. Gorgosaurus grew to be nine metres long and weighed two to three tonnes, with huge, crushing teeth that Therrien calls,. pic.twitter.com/0VYizTT6m4

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Fossil evidence reveals that large plant-eating dinosaurs, called megaherbivores, were often preyed upon by tyrannosaurids. Megaherbivores are those species weighing over a thousand kilograms, including ceratopsids, giant ornithomimosaurs, hadrosaurids, and sauropods.

Tyrannosaurids only developed the adaptations and powerful biting abilities needed for this specific diet when they were in their late juvenile or early subadult stages of growth, according to Sci.News.

Dr. François Therrien, a paleontologist at the Royal Tyrrell Museum and the lead author, pointed out a disadvantage. He stated, “Unfortunately, fossil evidence for diet in young tyrannosaurids is largely unknown, thus limiting our understanding of ontogenetic dietary shifts in these iconic predators.”

Two small dinosaurs inside the stomach of the Gorgosaurus libratus

In their study, the researchers discovered fragments of two small dinosaurs within the stomach of the Gorgosaurus libratus specimen. The scientists explained that prior to the creature’s death, the meat-eater tore apart two young herbivorous bird-like dinosaurs which belonged to the Citipes elegans species.

Moreover, instead of swallowing down the whole prey, the young tyrannosaur specifically consumed the hind limbs, which are the fleshiest parts. Animals hunted down included those dinosaurs known as caenagnathids. These resembled the Asian Oviraptor, according to researchers.