---

Tyrannosaurus rex tooth broken off and embedded in the skull of an adult Edmontosaurus.

This news article is based on the Press Release from MSU News Service and the Journal Article (Wyenberg-Henzler TCA, Scannella JB. 2026) from PeerJ.

---

A rare Late Cretaceous fossil from Montana captures a dramatic moment in dinosaur history: a broken Tyrannosaurus rex rex tooth embedded in the skull of an adult Edmontosaurus annectens. The skull also preserves up to 23 additional tyrannosaur bite marks.

The specimen, cataloged as MOR 1627 and housed at the Museum of the Rockies, was discovered in the santstone unit of the world-famous Hell Creek Formation of eastern Montana. This nearly complete, articulated Edmontosaurus annectens skull contains the tip of a large theropod tooth lodged in its nasal bone, which is direct physical evidence of a predator-prey interaction between two iconic dinosaurs of the Late Cretaceous.

A Rare Embedded Theropod Tooth Fossil

Dinosaur bones frequently show tooth marks, but identifying the exact predator responsible is often impossible. Scratches, punctures, and feeding traces can suggest carnivore activity, yet they rarely confirm the species involved.

An embedded tooth fossil is different. Theropod teeth — especially those of tyrannosaurids — have distinctive shapes, serrations (denticles), and proportions that make them taxonomically informative.

Detailed measurements of the tooth’s crown height, width, curvature, and denticle density indicate the embedded tooth belonged to a medium- to large-bodied tyrannosaurid. Given the known fauna of the Hell Creek Formation, that predator was almost certainly Tyrannosaurus rex.

CT Scans Reveal the Orientation of the T. rex Bite

Researchers used computed tomography (CT scanning) to digitally reconstruct the embedded tooth and analyze its position within the Edmontosaurus skull. The scans revealed:

The exact orientation of the broken tyrannosaur tooth
Its preserved dimensions and cross-sectional shape
Its likely position in the upper jaw (a maxillary tooth)

The surrounding bone shows no signs of healing or reactive growth, indicating the Edmontosaurus likely died at or very near the moment the tooth became embedded, making this one of the clearest examples of dinosaur predatory behavior ever discovered. The force required to break the tooth off into the bone also points to a lethal, powerful bite.

Evidence of Dinosaur Predator-Prey Behavior

The tooth's placement in the nasal bone indicates the tyrannosaur bit the Edmontosaurus on the snout, likely from the front. Comparisons with modern large carnivores that hunt big prey indicate the bite may have occurred while the predator attempted to either Subdue a struggling Edmontosaurus, deliver a fatal bite, or begin feeding on it shortly after death. While tooth marks alone can be ambiguous, an embedded T. rex tooth provides unusually direct evidence of Late Cretaceous dinosaur behavior.

Life in the Hell Creek Formation

The Hell Creek Formation of Montana records the final 1–2 million years of the Age of Dinosaurs, just before the mass extinction 66 million years ago. It preserves some of the most famous Late Cretaceous dinosaurs in North America, including Tyrannosaurus rex, Triceratops, and Edmontosaurus.

For fossil hunters, the Hell Creek is also one of the most exciting places in the world to prospect. On a Hell Creek fossil hunting trip, I even found a Tyrannosaurs tooth and an Edmontosaurus rib in the same rock layers that produced this remarkable skull.

Because these species are represented by large fossil samples, paleontologists can study their growth, variation, ecology, and behavior in remarkable detail. The MOR 1627 skull now adds rare, physical evidence of predator-prey interaction between T. rex and Edmontosaurus.

Why This T. rex Fossil Is Important

Direct evidence of dinosaur behavior is rare. Most reconstructions rely on indirect clues like trackways or bite marks. An embedded tyrannosaur tooth preserved in bone offers something far more concrete — a frozen moment of ecological interaction in the Late Cretaceous of Montana.

This fossil doesn’t just confirm that Tyrannosaurus rex fed on Edmontosaurus. It shows how that interaction may have unfolded, capturing a violent encounter between two of the most iconic dinosaurs that ever lived.

---

---

Journal Article:

Wyenberg-Henzler TCA, Scannella JB. 2026. Behavioral implications of an embedded tyrannosaurid tooth and associated tooth marks on an articulated skull of Edmontosaurus from the Hell Creek Formation, Montana. PeerJ 14:e20796 https://doi.org/10.7717/peerj.20796.

---

Recommended Dinosaur Books and Educational Items:

---

High quality Dinosaur teeth by Fossilera

---

FAQ's about the T. rex Embedded Tooth Article

• Where was the T. rex tooth found?
  The Tyrannosaurus rex tooth was found embedded in an Edmontosaurus skull from the Hell Creek Formation in Montana, a famous Late Cretaceous fossil site.
• Did the Edmontosaurus survive the T. rex attack?
  No. The force required to break a T. rex tooth and embed it in bone indicates deadly force. Numerous additional tooth scrape marks on the skull further support that the Edmontosaurus did not survive the attack.
• How old is the Hell Creek Formation fossil?
  The fossil comes from the Hell Creek Formation, which dates to about 66 million years ago at the very end of the Late Cretaceous period.
• Why is an embedded T. rex tooth important?
  An embedded T. rex tooth provides rare direct evidence of dinosaur predator-prey behavior, preserving a physical interaction between Tyrannosaurus and Edmontosaurus.
• What does this fossil reveal about T. rex behavior?
  The embedded tooth and multiple scrape marks suggest powerful, forceful biting consistent with active predation rather than simple scavenging.

Paleontology News Article FAQ's

---