A transformative study conducted by paleontologists at Aarhus University challenges the long-held belief that tyrannosaurs were exclusively apex predators. By analyzing 16 meticulously mapped bite marks on the bones of a 75-million-year-old Tyrannosaurus rex, researchers found that smaller Tyrannosaurs scavenged on their larger tyrannosaurid relatives.
Visualization of a small Tyrannosaurus rex eating the carcass of a larger Tyrannosaurus. Image credit: Yu Xin, Shen Li, Liang Junwei, Aarhus University.
“Tyrannosaurus was the apex terrestrial predator in the Northern Hemisphere during the Late Cretaceous period,” stated lead author Josephine Nielsen, a master’s student at Aarhus University, alongside her research team.
“Species found in the Campanian region of the northern interior of western North America include Daspletosaurus and Gorgosaurus.”
“Tyrannosaurs were substantial predatory carnivores with massive skulls capable of enduring extreme bite forces and stresses.”
“Bites can crush and process bones, even from prey significantly larger than themselves, as evidenced by coprolites containing bone fragments.”
“However, such fossils do not provide direct evidence of biting strength, and debates continue concerning the feeding strategies of Tyrannosaurus and their ecological interactions.”
Nielsen and her colleagues utilized advanced 3D scanning technology to identify 16 bite marks on a fossilized metatarsal (foot bone) of a giant tyrannosaur.
“By examining the depth, angle, and position of the bite marks in a virtual 3D setting, we demonstrated that these marks were not incidental,” Nielsen remarked.
“These distinct tooth impressions of a smaller tyrannosaurus indicate scavenging on much larger relatives.”
This groundbreaking study sheds light on the recycling of resources in the age of dinosaurs, revealing their behaviors as scavengers.
The robust leg bones may have been consumed late in the decomposition phase, after most of the flesh had been stripped away.
“The bone lacks signs of healing after a bite from a smaller dinosaur,” Nielsen noted.
“The marks were found on a foot that had minimal flesh, indicating the dinosaur was possibly ‘sweeping’ and scavenging the last remnants of a carcass.”
The authors conducted their research using digital models and 3D printed replicas instead of original bones.
The metatarsals measured 10 cm in length and belonged to a tyrannosaurid estimated to be between 10 to 12 meters long and weighing several tons during its lifetime.
The bones were uncovered by amateur fossil hunters in the Judith River Formation in Montana. This region is an eroded landscape that acts as a geological archive of a 75-million-year-old ecosystem, teeming with dinosaur fossils.
“What makes this study exceptional is not only the insight into ancient dinosaur food chains, but also the innovative technology employed to extract these details.”
“By developing a digital version, we can now zoom in on intricate details.”
For more in-depth findings, visit this study published in the journal Evolving Earth.
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Josephine Nielsen et al. 2026. Investigating size-asymmetric feeding in tyrannosaurids using metatarsal tooth impressions from the Judith River Formation, Montana, USA. Evolving Earth 4:100107; doi: 10.1016/j.eve.2026.100107
Source: www.sci.news
