Fossilized dinosaur bones discovered in Wyoming bear tooth marks that were likely left by Tyrannosaurus rex, according to a study published July 15, 2026, in the open-access journal PLOS One. The research was led by Bethania C. T. Siviero of Loma Linda University and her colleagues.
Tooth marks preserved on fossil bones offer rare clues about dinosaur behavior, feeding habits, and predator-prey interactions in ancient ecosystems. In this study, researchers examined depressions, punctures, holes, and grooves that may have been caused by bites. They also combined previous research with their own observations to develop a practical guide for identifying possible tooth marks in dinosaur fossils.
Researchers Examined More Than 3,000 Cretaceous Dinosaur Bones
The research team analyzed more than 3,000 fossil bones collected in northeastern Wyoming. The specimens date to the Late Cretaceous period, approximately 72 to 66 million years ago.
Most of the bones belonged to Edmontosaurus annectens, a large herbivorous dinosaur recognized by its broad, duck-like bill.
Only 12 bones displayed possible evidence of tooth damage. Four contained particularly distinctive tooth patterns that matched the expected shape and spacing of T. rex teeth. Based on these features, the researchers identified T. rex as the most likely source of the marks.
The remaining damaged bones may have been bitten by other predators or scavengers that lived in the region during the Late Cretaceous, including carnivorous dinosaurs and crocodilians.
Fossils Reveal Possible Feeding and Scavenging Behavior
Most of the marked bones showed no evidence of healing in the surrounding tissue. This finding suggests that the bites occurred near the time of death or after the animals had already died.
When combined with earlier research from the same fossil site, the findings suggest that some dinosaurs may have been killed by predators. Their carcasses could then have remained exposed, giving scavengers time to feed before the bones were buried and preserved as fossils.
How Scientists Distinguish Tooth Marks From Other Fossil Damage
Identifying genuine dinosaur tooth marks can be challenging. Bites may leave punctures, grooves, or furrows in bone, but similar features can also be produced by disease, insects, weathering, and erosion.
Before using fossil damage to reconstruct dinosaur behavior or ancient food webs, paleontologists must determine how each mark was created. By establishing clearer criteria for recognizing tooth damage, this study improves an important method for investigating predator-prey relationships in the fossil record.
The authors add: “Correctly identifying bone depressions and perforations is important because not all of these features are tooth marks. Some are caused by diseases, while others result from post-mortem processes such as insect activity or other processes due to bone exposure. Distinguishing between these different types of bone modifications is essential, as they can provide valuable information about an animal’s condition before death as well as the processes that affected its remains after death.”
“The study of tooth marks on fossil bones is important because it provides valuable insights into animal behavior and interactions between species.”
The study was supported by internal funding from Loma Linda University.
Source: www.sciencedaily.com