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Stomach Contents of 75,000-Year-Old Fossil in Canada Explains Tyrannosaur’s Predatory Reign

Tyrannosaurus Rex
Tyrannosaurus Rex. ScottRobertAnselmo, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

A 75-million-year-old fossil of a juvenile Gorgosaurus libratus, a cousin of the famous T. rex, was unearthed in 2009 in Dinosaur Provincial Park, Alberta, Canada. An old discovery that has shed new light on why tyrannosaurs were the rulers of their prehistoric world. A recent study published in Science Advances provided fascinating insights into this dinosaur’s unique dietary choices and predatory behavior by investigating its well-preserved stomach.

A Unique Find in Alberta

Royal Tyrrell Museum, Drumheller, Alberta, Canada.
Royal Tyrrell Museum, Drumheller, Alberta, Canada. Image by Scur57, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons

Unlike the hefty adults, the juvenile specimen in the Royal Tyrrell Museum of Palaeontology was relatively svelte. It died between the ages of five and seven. But it was by no means a baby! The discovered juvenile Gorgosaurus was approximately 13 feet long and weighed around 700 pounds. Which is only around 10% of the weight of an adult.

A Formidable Presence

A T-Rex skeleton found at Palais de la Découverte, Paris.
A T-Rex skeleton found at Palais de la Découverte, Paris. Image by Copyright © 2005 David Monniaux – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=494543

The Tyrannosaurs, including the Gorgosaurus, were among the most formidable predators of their era. Adult T. rexes towered up to 13 feet at the hip and could reach lengths of 43 feet. Weighing between 5.5 and 9 tons. That’s the equivalent weight of three Mini Coopers! However their immense size, T. rexes also had some limitations. Adult T. rexes could only move at speeds of up to 12 mph without risking bone damage. Basically, a human actually had a chance to outrun them!

Juvenile vs. Adult Hunting Strategies

Tyrannosaurus rex attacking einiosaurus
Tyrannosaurus rex attacking einiosaurus. Image by Elenarts via Depositphotos

Aside from speed, the new study found juvenile and adult tyrannosaurs had different hunting techniques. Young rexes targeted smaller prey, using their narrow skulls and blade-like teeth. In contrast, adults had massive skulls and strong teeth capable of crushing larger animals. 

It Comes Down To Bite Force

Tyrannosaurus Rex in Budakeszi Vadaspark, Dínó Park.
Tyrannosaurus Rex in Budakeszi Vadaspark, Dínó Park. Image by Elekes Andor, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons

The new findings of the study highlight the contrasting role of bite force in juvenile and adult tyrannosaurs. While juvenile T. rexes had serrated teeth which was better for hunting smaller prey, adults developed a powerful bite capable of crushing bones. An adult T. rex’s bite force could exert up to 7,800 pounds. That’s enough to crush an entire car! This development in jaw strength would occur after the tyrannosaur completed its teenage growth spurt, marking its transition to larger prey.

Juveniles and Adults Coexisted

tyrannosaurus rex extinct
Illustration of Tyrannosaurus Rex in the jungle. Image by Orlaimagen via Depositphotos

Unlike human teens and their parents, researchers concluded that juveniles and adults of the tyrannosaur family could happily coexist in the same environment. They cleverly avoided direct competition by targeting different prey through their different physical adaptations. This ecological separation helped them occupy distinct roles within their food chain which researchers believe contributed greatly to their dominance as apex predators.

What an Evolutionary Success 

Tyrannosaurus from the Cretaceous era
Tyrannosaurus from the Cretaceous era. Image by warpaintcobra via Depositphotos

The ability of tyrannosaurs to occupy both mesopredator and apex-predator roles may have contributed to their evolutionary success. In fact, earlier research shows some relatives of the T. rex might have hunted in packs! This adaptability allowed them to thrive in their ecosystems and increase their chance of survival. So I guess one could say those Jurassic Park depictions weren’t too far off.

The Diverse Diet of the Picky Eater

Juvenile Gorgosaurus preserving stomach contents.
Juvenile Gorgosaurus preserving stomach contents. Image by Therrien, F.; Zelenitsky, D. K.; Tanaka, K.; Voris, J. T.; Erickson, G. M.; Currie, P. J.; DeBuhr, C. L.; Kobayashi, Y., CC BY 4.0 https://creativecommons.org/licenses/by/4.0, via Wikimedia Commons

The fossilized stomach contents of the juvenile Gorgosaurus provide insight into its diet. According to study coauthor François Therrien, the rock inside the rib cage was removed to reveal the complete hind legs of two baby dinosaurs, both under a year old. This tyrannosaur seemed to prefer the meaty thighs of its prey. Which I think is an excellent choice given how good modern-day chicken thighs taste.

Tyrannosaurs as Intelligent 

3d illustration of a Tyrannosaurus rex showing one way it might have looked like.
3D illustration of a Tyrannosaurus rex showing one way it might have looked like. Image via Depositphotos

The picky eating habits of the juvenile Gorgosaurus actually imply a level of dietary sophistication. Thomas Carr, a biologist not involved in the study, compares their intelligence to that of modern orcas, who are also known for their selective eating. While it is a bit of a stretch to call tyrannosaurs the orcas of their time, their hunting strategies are certainly clever. At least more clever than today’s finicky children. Why can’t our toddlers catch their own prehistoric chicken at age seven?

Fossils as Time Capsules

Skeleton of Tyrannosaurus in comparison with human skeleton
Skeleton of Tyrannosaurus in comparison with human skeleton. Image by William Diller Matthew, via Wikimedia Commons

The well-preserved fossil of the juvenile Gorgosaurus serves as a time capsule. Like a camera pointed through a time machine window, it gives us a detailed snapshot of ancient predatory behavior. It helps us understand the dynamics of ancient ecosystems and how their evolutionary paths led to their survival or downfall.

The Tyrannosaur Legacy

T. Rex in its natural habitat
T. Rex in its natural habitat. Image by warpaintcobra via Depositphotos

In the field of paleontology, tyrannosaurs have left a lasting legacy due to their hulking size and hunting prowess. Their ability to adapt and thrive in various ecological roles is a testament to their evolutionary success. Despite their extraterrestrial bad luck! 

To conclude

Tyrannosaurus, Dinosaurs Alive Exhibition, Science City
Tyrannosaurus, Dinosaurs Alive Exhibition, Science City. Image by Biswarup Ganguly, CC BY 3.0 https://creativecommons.org/licenses/by/3.0, via Wikimedia Commons

The discovery of this juvenile Gorgosaurus fossil provides a fascinating glimpse into the dominance of tyrannosaurs as apex predators. Examining their diet and hunting techniques allows scientists to gain insights into their ecological complexity and adaptability.  As research continues, I look forward to the secrets we have yet to dig up!

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