A fascinating fossil has been found in Canada, containing the final meal of a juvenile tyrannosaur and indicating its preference for prehistoric fast food.

Although tyrannosaurs were known for being intimidating dinosaurs that roamed the Earth, adult ones had large bodies, big heads, and powerful jaws, while the younger ones were smaller in comparison with thin legs, sharp teeth, and slender skulls.

The change has been linked to a change in eating habits as the tyrannosaurs grew older and needed more energy: although there is proof that adults hunted and ate large herbivores, like duck-billed and horned dinosaurs, younger individuals did not have the necessary teeth to do so.

However, it has been unclear what exactly the young individuals consumed.

A remarkable fossil has been discovered, showcasing the well-preserved contents of a juvenile tyrannosaur’s stomach and providing a unique glimpse into its eating habits.

Dr. Darla Zelenitsky, a co-author of the study from the University of Calgary, stated that this is the first concrete proof of the diet or feeding habits of a young tyrannosaur.

The fossil of the juvenile Gorgosaurus libratus was unearthed in 2009 by Darren Tanke, a technician at the Royal Tyrrell Museum of Palaeontology, in Dinosaur Provincial Park, Canada. It is estimated to be around 75 million years old.

The team reported that the juvenile tyrannosaur weighed approximately 350kg. Their examination of the growth rings in the fossilized bones indicated that it died at a young age, around five to seven years old.

However, it did not perish with an empty stomach.

“I observed in late 2010 that small knuckle bones were visible on the ribcage of the tyrannosaur during the preparation process,” stated Dr. François Therrien, co-author of the research and curator of dinosaur palaeoecology at the Royal Tyrrell Museum.

In a publication in Science Advances, the researchers state that they found the preserved bodies of two young citipes within the ribcage. These citipes were similar in size to turkeys and had a head resembling a parrot. They were likely agile runners, similar to emus.

It was observed that the citipes were eaten in two different occasions based on the level of stomach acid damage. However, the remains mostly consisted of hind legs, indicating that the young tyrannosaur did not consume its entire prey.

Zelenitsky stated that the young tyrannosaurus had a preference for citipes drumsticks, speculating that perhaps the legs were the most substantial part of the prey. The precision feeding was made possible by the gorgosaurus skull.

The team stated that it is uncertain how the tyrannosaur died, but it seems to have died within a week of its last meal.

This is the initial instance of a tyrannosaur fossil being discovered with its stomach contents intact. Additionally, there is an added benefit to this discovery.

Therrien stated that the legs found in the stomach make up the most comprehensive citipes skeleton ever discovered.

According to Professor Stephen Brusatte from the University of Edinburgh, a paleontologist not connected to the study, the fossil provides concrete proof of the diet of a tyrannosaur.

The speaker stated that this is not speculation or a sequence of guesses based on interpreting bite marks or fossilized feces, but rather it is solid evidence from inside the gut. It is a record of the final meal of a tyrannosaur, preserved in stone.

According to Brusatte, the fossil provides evidence for the theory that tyrannosaurs altered their eating habits as they aged, transitioning from consuming small to larger prey.

Although Brusatte agrees that the insights are logical, he also mentions that there is another potential explanation: young tyrannosaurs may have simply eaten prey that was already killed by adult tyrannosaurs.

“However, this does not appear to be the scenario in this case. According to the researcher, small tyrannosaurs consumed small prey, suggesting that they actively pursued their own food and adjusted their target as they matured. This indicates that tyrannosaurs played various roles in the food chain as they developed, which is quite interesting.”

Source: theguardian.com