Numerous bone fossils have been discovered in a Cretaceous bone bed in Wyoming, USA. Tyrannosaurus rex is believed to have scavenged the remains of a platypus dinosaur species known as Edmontosaurus anectens.
Reconstruction of Edmontosaurus anectens. Image credit: Dani Navarro.
“Determining the origin of perforating lesions on fossil bones can be challenging. Many are presumed to be tooth marks, yet other explanations are often more plausible,” stated Bethania Siviero, a paleontologist from Loma Linda University, along with her colleagues.
“This confusion arises from the criteria used to identify tooth marks, which can be ambiguous without considering the context of the lesion.”
“Misidentifying these marks has led to inaccurate interpretations of the behavior of these ancient animals.”
“Our research critically reevaluates previous criteria for identifying tooth marks in fossil bones.”
In their comprehensive study, Siviero and her team analyzed 3,013 bones excavated between 1997 and 2017 from a significant paleontological site near Hanson Ranch Station in northeastern Wyoming, part of the Lance Formation.
The overwhelming majority of these bones belonged to a singular species of large herbivorous hadrosaur, Edmontosaurus anectens.
Only a minor fraction, specifically 13 out of the 3,013 bones, exhibited marks that appeared to resemble tooth marks.
Upon detailed analysis, including advanced CT scans, the paleontologists concluded that one of the marks identified was simply a natural anatomical feature and not a bite mark.
Encounter between adults of Nanotyrannus lansensis (left) and two juvenile Tyrannosaurus rex, with a subadult T. rex observing from a distance. Image credit: Jorge Gonzalez.
Among the 12 bones confirmed to have authentic tooth marks, which included ribs, vertebrae, radius, and ulna, four distinct patterns were identified, linked to two known endemic species: Cuneticnus pararealm and linicnus sawtooth.
By comparing the spacing of these marks with the tooth structure of known predators from the same ecosystem, researchers inferred that Tyrannosaurus rex was likely responsible for the bite marks.
The majority of the damaged bones displayed no signs of healing, indicating that the animals were likely bitten before, during, or shortly after death, suggesting evidence of scavenging rather than active predation.
Additionally, scientists utilized the Wyoming bone bed to enhance broader scientific criteria for recognizing tooth marks on fossil bones.
“Not all features indicative of depressions and holes in bone are tooth marks, thus accurate identification is crucial,” the researchers stated.
The team’s findings were published today in the online journal PLoS ONE.
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BCT Cibiero et al. 2026. Identification of Cretaceous (Maastrichtian) tooth marks on Edmontosaurus anectens bone bed of the Lance Formation, Wyoming, USA PLoS ONE 21 (7): e0351939; doi: 10.1371/journal.pone.0351939
Source: www.sci.news