T. rex was likely responsible for some tooth marks on fossil bones from Cretaceous era

A recent study published in PLOS One on July 15, 2026, suggests that some tooth marks found on fossilized dinosaur bones from the late Cretaceous period in northeastern Wyoming were likely caused by Tyrannosaurus rex. Researchers led by Bethania C. T. Siviero from Loma Linda University analyzed over 3,000 bones from the region, which date back approximately 72 to 66 million years. Among these, 12 bones bore tooth marks, four of which exhibited distinctive patterns that the researchers attribute to T. rex. These markings include punctures, furrows, and other indentations consistent with the teeth and feeding habits of the apex predator. The study provides a detailed analysis of different types of tooth traces observed on both neural spine fragments and rib specimens. For instance, neural spine fragment HRS01295 showed punctures on opposing surfaces, while another fragment, HRS03650, displayed a deep and curved score identified as the ichnotaxon Linichnus serratus. Similarly, rib fragments like HRS09477 featured furrows and punctures, with accompanying drag marks suggesting the force applied during biting. Other rib specimens, such as HRS03387 and HRS09954, showed parallel scores indicative of different ichnotaxa, including Knethichnus parallelum. The researchers emphasized the importance of distinguishing true tooth marks from other potential causes, such as post-mortem erosion or pathological conditions. They developed a guide based on prior studies and their new findings to help identify and interpret these marks accurately. This guide aims to enhance the understanding of prehistoric ecosystems and animal behaviors through the analysis of fossilized remains. Most of the marked bones did not show signs of healing, implying that the tooth marks were inflicted either at or shortly after the time of death. This aligns with previous research on the same site, which suggested that some of the animals might have been preyed upon. Their carcasses could have been exposed to scavengers and environmental factors before being buried and fossilized. The study's lead author noted the significance of correctly identifying bone depressions and perforations. Accurate identification is crucial for understanding predator-prey dynamics and the ecological interactions of the Cretaceous period. The presence of multiple carnivore species, including other dinosaurs and crocodilians, adds complexity to the interpretation of the tooth marks, as some could have been made by non-T. rex predators. The research team’s work contributes to ongoing efforts to reconstruct ancient environments and behaviors through fossil records. By providing a systematic approach to analyzing tooth marks, the study offers a valuable tool for future paleontological investigations. The findings suggest that T. rex played a significant role in the ecosystem of the late Cretaceous, potentially influencing the survival and distribution of its prey species. The excavation site, located in the Upper Cretaceous Lance Formation in Wyoming, has yielded numerous fossils, predominantly from Edmontosaurus annectens, a large herbivorous dinosaur. The presence of multiple carnivore species in the area further supports the idea that predation was a common occurrence. The study underscores the necessity of rigorous analysis to differentiate between various causes of bone damage, ensuring accurate interpretations of prehistoric life.