🦕 A Startling New Discovery in Dinosaur Behavior

In a revelation that flips traditional views of tyrannosaur dominance, researchers have uncovered compelling evidence of a juvenile tyrannosaur scavenging the remains of a much larger adult of its own kind. This finding, detailed in a groundbreaking 2026 research paper published in the journal Evolving Earth, centers on a fossilized foot bone from Montana's Judith River Formation. The Late Cretaceous deposit, dating back approximately 77 to 75 million years, is renowned for its diverse dinosaur fauna, including several tyrannosaurid species such as Daspletosaurus and early relatives of Tyrannosaurus rex.

The specimen, cataloged as BDM 124 at the Badlands Dinosaur Museum in Dickinson, North Dakota, is a partial left metatarsal II—a long, slender bone in the foot that connects the ankle to the toes. Discovered in 2012 by amateur fossil collectors Brent and Rod Olson on private land in central Montana, it was generously donated to the museum in 2023. What makes this bone extraordinary are the multiple tooth marks etched into its surface, revealing a tale of opportunistic feeding long after the adult had perished.

Advanced analysis using high-resolution 3D scanning and morphometric techniques allowed the international team to identify 16 distinct tooth marks. These marks, characterized by shallow depths and specific spacing of 7 to 13 millimeters, match the premaxillary dentition— the front teeth in the upper jaw—of a small, juvenile tyrannosaurid. No signs of healing around the punctures confirm the bites occurred postmortem, pointing to scavenging rather than predation.

Deciphering the Bite Marks: Science Behind the Evidence

To understand the significance, it's essential to grasp how paleontologists identify feeding traces. Tooth marks on fossils are classified using systems like the Category-Modifier (CM) method, which categorizes them by shape, depth, and orientation—such as punctures, scores, or pits. In BDM 124, the marks cluster into sets, suggesting repeated bites from the same small jaw, as confirmed by Non-metric Multidimensional Scaling (NMDS) analysis. This statistical technique groups similar features, revealing patterns consistent with a single juvenile actor.

The metatarsal belonged to a large adult, estimated at over 8 meters long, while the biter was likely under 4 meters— a stark size asymmetry never before documented in tyrannosaur cannibalism. Previous cases typically showed larger adults feeding on juveniles, but this reverses the dynamic, highlighting how even young tyrannosaurs could exploit carcasses in a competitive ecosystem.

The Judith River Formation's environment was a coastal floodplain with rivers, forests, and seasonal droughts, fostering fierce competition for food. Tyrannosaurids here grew rapidly but faced high mortality from injuries, starvation, or intra-species combat, leaving ample carcasses for scavengers.

Historical Precedents: Building a Case for Cannibalistic Tendencies

This isn't the first hint of tyrannosaurs eating their own. Fossil evidence has accumulated over decades, painting a picture of pragmatic carnivores unbound by taboos.

• In 2010, a study examined four Tyrannosaurus rex bones with deep gouges matching T. rex teeth, suggesting scavenging or post-combat feeding in the Hell Creek Formation.
• 2015 research on a Daspletosaurus skull and jaw from Alberta's Dinosaur Park Formation revealed pre- and postmortem bites, likely from another tyrannosaurine, indicating both fights and scavenging. The full paper is available here.
• A 2018 analysis of a juvenile tyrannosaurid fibula from Wyoming's Lance Formation bore tooth traces from a large adult, probably T. rex, reinforcing adult-on-juvenile patterns.

These cases, combined with BDM 124, suggest cannibalism was a regular, opportunistic strategy amid scarce resources.

Photo by Fynephoqus on Unsplash

Implications for Tyrannosaur Ecology and Society

What does this mean for how we view these apex predators? Tyrannosaurids, part of the Theropoda group of bipedal carnivores, underwent extreme ontogenetic shifts—juveniles were slender, pack-hunting piscivores or small-game specialists, maturing into solitary bone-crushers. This discovery implies juveniles filled scavenger niches, accessing meat on low-value carcass parts like feet after larger predators took prime cuts.

Ecologically, it underscores a brutal food web where even giants became meals. Population densities were low—perhaps one T. rex every 100 square kilometers—intensifying competition. Cannibalism likely aided survival during famines, reducing competition and recycling nutrients.

Socially, it challenges lone-wolf stereotypes. Bite-marked bones hint at aggression, possibly over territory or mates, mirroring modern big cats.

Modern Analogies: Lessons from Today's Carnivores

Cannibalism isn't alien; it's documented in lions (prides eat cubs), crocodiles (adults devour young), and Komodo dragons (frequent conspecific predation). These behaviors thrive in unpredictable environments, much like the Cretaceous. For tyrannosaurs, juveniles scavenging adults parallels hyenas or vultures cleaning remains, promoting ecosystem balance.

Read the full new study for technical details: Investigating size-asymmetric feeding among tyrannosaurids.

Paleontology Careers: Join the Hunt for Ancient Secrets

Discoveries like BDM 124 stem from dedicated paleontologists. If you're passionate about unearthing history, consider research jobs in geology or paleontology. Universities worldwide seek experts for fieldwork and analysis—explore higher education jobs in academia. Aspiring professors can find openings at professor jobs listings.

For hands-on experience, check career advice on academic CVs. More on dinosaur research at the Badlands Dinosaur Museum press release.

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Looking Ahead: Future Research Directions

The team—Josephine Nielsen (Aarhus University), Denver Fowler (Badlands curator), Taia Wyenberg-Henzler, Aase Roland Jacobsen, and Christof Pearce—calls for more 3D analyses of bite marks. Ongoing digs in Judith River could yield jaws or skeletons linking biter and bitten taxonomically.

This evidence enriches our understanding of tyrannosaur life, blending forensics, stats, and ecology. As technology advances, expect more revelations from 75-million-year-old bones.

In summary, tyrannosaur cannibalism underscores nature's pragmatism. Share your thoughts in the comments—have you rated your professors on Rate My Professor? Explore higher-ed jobs or university jobs to contribute. For career tips, visit higher ed career advice.