In this article, you will find a report on the discovery of the first fossilized contents of a Tyrannosaurus’s stomach, revealing the diet of this fearsome predator.
Discovery of Stomach Contents
The stomach contents of one member of this dinosaur family were described in a new study published on Friday in the journal Science Advances. This astonishing discovery provides insight into the diet of the Tyrannosaurus and its role in ancient ecosystems, which had previously only been inferred through speculation.
Discovery of the Specimen
Darren Tanque, a preparator at the Royal Tyrrell Museum of Palaeontology in Alberta, found the specimen in the Dinosaur Provincial Park and carefully extracted it from the rock that held it. He described it as “the discovery of his life,” according to François Therrien, a co-author of the study and the museum’s Curator of Dinosaur Palaeoecology.
Analysis of the Contents
Remains of two feathered dinosaurs with toothless beaks were identified in the stomach of a young Tyrannosaurus known as Gorgosaurus libratus, a type of tyrannosaurid (the family that includes its more famous cousin Tyrannosaurus rex). Before the discovery of this new fossil, scientists were only able to infer something about the Tyrannosaurus’s diet. These conclusions were based on factors such as skull structure, teeth in fossils, bite marks on megaherbivore fossils, and at least one coprolite, or fossilized stool. Bones found near the Tyrannosaurus fossil were also interpreted as stomach contents. The conditions that can lead to the preservation of stomach contents in rocks are unusual: the animal must die before fully digesting its prey and must be buried quickly under mud or another medium.
Bony Growth Analysis
Analysis of bony growth revealed that this Tyrannosaurus was young, between five and seven years old, and both of its prey lived for less than one year. The varying amounts of stomach acid etched on the prey remains suggest that the animals were consumed within hours or days as separate meals. The fact that the remains include fully articulated limbs from two feathered dinosaurs of the same age, size, and type indicates that these animals were a favored food for this particular Tyrannosaurus.
Effect of Stomach on Prey
The feathered dinosaur legs helped identify the species as Citipes elegans – very rare specimens in terms of their relatively pristine condition. Darla Zelenitsky, an associate professor at the University of Calgary, states that “the Tyrannosaurus’s stomach actually preserved the Citipes and allowed it to be retained – which is really amazing.” She adds that these fossils are “the most complete remains known for that species.”
Interpretation of the Discovery
The Tyrannosaurus may have dismembered the small prey and swallowed the limbs, leaving the rest of the body behind. Therrien suggests that these limbs might have been “the tastiest part” of the animal and wonders, with a smile, if this Tyrannosaurus “didn’t want to bother getting rid of some feathers.”
Impact of the Discovery on Dinosaurs
Feathered dinosaur nests usually contain 30 or more eggs. With such large nests, “you can imagine, at certain times of the year, depending on the species and its breeding season, that this would not be an uncommon prey for predators,” says Zelenitsky. For this reason, she is not surprised to find the remains of these species in the stomach of this Tyrannosaurus, especially since she “cannot imagine adults going after these small dinosaurs the size of chickens or turkeys.”
Interpretation of Stomach Nature
Zelenitsky expects that the Tyrannosaurus may have had a two-part stomach, like birds and crocodiles – closely related animals that share a common ancestor with dinosaurs. She notes that the positioning of the two Citipes pieces strongly supports this possibility, as the legs from the first meal show more “chemical digestion,” while the legs from the last meal exhibit more “mechanical digestion or breakdown.”
Impact
The Discovery on the Evolution of Tyrannosaurs
This discovery also helps support what some paleontologists believe is key to the success of tyrannosaur evolution: their ability to occupy different ecological environments throughout their lives. The mystery of one fossil revolves around a significant shift in Cretaceous ecosystems. There used to be a variety of sizes and types of predators, but by the end of the Cretaceous in Asia and North America, there were only two types: massive tyrannosaurs and smaller dromaeosaurs (feathered theropods like those belonging to the genus Velociraptor) – and “nothing in between,” Teryan says.
Interpretation of the Phenomenon
It has been suggested that tyrannosaurs were able to occupy all the ecological environments that were previously held by medium- and large-sized predatory dinosaurs throughout their evolution: tyrannosaurs eat smaller prey when they are young and switch to megaherbivores as they grow. Teryan says they may have been very successful as a species because they “evolved the ability to occupy all those ecological environments throughout their own lifetimes.”
A Different Opinion
However, Zanno disagrees. She says, “In my opinion, the shift in prey preference must have been widespread among dinosaur predators to explain these phenomena. The dominance of tyrannosaurs in the late Cretaceous ecosystems is a complicated story we have yet to untangle, but I’m sure it’s a problem we will happily face in the years to come.”
Conclusion
This discovery of a tyrannosaur seems to provide an amazing insight into at least one animal. Zilenitski says, “Although unfortunately for the small tyrannosaur, lucky for us it died when it did after having those meals. Let’s hope more are found!”
Copyright and Permissions: Jane Timons discovered her passion for paleontology later in life. She is a freelance writer based in New Hampshire, and her work can be found in Gizmodo, Ars Technica, and The New York Times.
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