Study finds marks in fossilized dinosaur bones may not always be bite marks

Marks in fossilized dinosaur bones may have several causes ranging from pre-mortem natural causes to postmortem alterations, including bite marks, according to a new study.

Researchers said the study of marks on fossil bones is important because it provides valuable insights into animal living conditions, diseases, behavior and interactions between species.

"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," said Bethania C. T. Siviero, PhD, an assistant professor at Loma Linda University School of Medicine Department of Pathology and Human Anatomy and the study's lead author. "Figuring out what caused holes and other marks on fossil bones is not always easy. Context is important. Many are labeled as bite marks, even though they may have other causes, leading to mistaken conclusions about the behavior of extinct animals."

Researchers published their findings last week in a manuscript titled Identification of Tooth Traces from a Cretaceous (Maastrichtian) Edmontosaurus annectens Bonebed in the Lance Formation, Wyoming, U.S.A. The study, by C. T. Siviero and colleagues, appeared in PLOS One Journal.

The team studied more than 3,000 dinosaur bones, with only less than 0.4% showing clear evidence of bite marks. The size, shape, and spacing of some of these marks closely match the teeth of Tyrannosaurus rex, making it the most likely animal to have left them, although some of the other bones analyzed may have been marked by other animals living at the same time, such as crocodiles, Siviero said.

Most of the bitten bones show no signs of healing, indicating that the bites were made either around the time the animals died or after they were already dead. Other evidence, including surface alterations by weathering, and damage caused by other organisms, suggests that the carcasses remained exposed on the landscape for some time before they were buried, Siviero said.

As a result of this study, the authors' revised and refined the criteria for the identification of bite marks on fossil bones considering also other types of holes that could potentially be mistaken by bite marks.

The team examined bones that had been excavated from a bone bed in Wyoming from 1997 to 2017. The bones are now stored at Southwestern Adventist University in Keene, Texas.

The study was performed by researchers from Loma Linda University, Western University of Health Sciences, The Master's University, Southern Adventist University, and Southwestern Adventist University.