New research led by Aarhus University paleontologists overturns the image of tyrannosaurs as pure apex predators. An analysis of 16 precisely mapped bite marks on a 75-million-year-old tyrannosaur bone reveals that smaller tyrannosaurs scavenged their own kind.
Visualization of a small tyrannosaur feeding on a carcass of a larger tyrannosaur. Image credit: Yu Xin, Shen Li & Liang Junwei, Aarhus Universitet.
“Tyrannosaurs were the dominant terrestrial predators of the northern hemisphere in the Late Cretaceous,” said first author Josephine Nielsen, a Master’s student at Aarhus University, and her colleagues.
“Species known from the Campanian of the northern Western Interior of North America include Daspletosaurus, and Gorgosaurus.”
“Tyrannosaurids were megapredatory carnivores, with heavily built skulls well suited to withstand extreme bite forces and high stress.”
“A bite capable of processing bone, even of prey much larger than themselves, as evidenced by coprolites containing bone fragments.”
“Although such remains do not in themselves constitute direct evidence of bite force, and debate remains on tyrannosaur feeding strategies and how they might have interacted.”
Using 3D scanning, Nielsen and co-authors identified 16 bite marks on a fossilized metatarsal (foot bone) that belonged to a giant tyrannosaur.
“I have analyzed the depth, angle, and placement of the marks in a virtual 3D environment and can document that these bite marks did not occur by chance,” Nielsen said.
“They are precise impressions from the teeth of a smaller tyrannosaur that fed on a much larger relative.”
The study provides insight into how nothing went to waste during the age of dinosaurs and that these animals were also scavengers.
The tough foot bones were likely eaten late in the decomposition process, after most of the meat was already gone.
“The bone shows no signs of healing after the smaller dinosaur bites into it,” Nielsen said.
“Since the marks are located on the foot, where there is very little meat, it suggests that the dinosaur was ‘cleaning up’ and eating the last remains of an old carcass.”
The authors did not have the original bone in her hands; instead, they worked with a digital representation and a 3D-printed version.
The metatarsal is 10 cm long and originates from a tyrannosaur that, in life, measured 10-12 m and weighed several tons.
The bone was found by an amateur fossil hunter in the Judith River Formation in Montana, an eroded landscape that serves as a geological archive of a 75-million-year-old ecosystem teeming with dinosaur fossils.
“What makes this study special is not just the knowledge of how the food chain functioned among dinosaurs millions of years ago, but the technique used to read the details,”
“By creating a digital version, I’ve been able to zoom in on very small details.”
The results appear in the journal Evolving Earth.
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Josephine Nielsen et al. 2026. Investigating size-asymmetric feeding among tyrannosaurids using tooth marks on a metatarsal from the Judith River Formation, Montana, USA. Evolving Earth 4: 100107; doi: 10.1016/j.eve.2026.100107
