Research sheds light on dinosaur sexual dimorphism
Paleontologists may be on the brink of accurately distinguishing between male and female dinosaurs, particularly hadrosaurs, following a recent study published in the journal iScience, reports BritPanorama.
Hadrosaurs, commonly referred to as duck-billed dinosaurs, proliferated during the Late Cretaceous Period, with fossils found across various continents. Notable among these are some specimens that display injuries to their vertebrae, specifically located at the base of their tails. These injuries are thought to result from mating behaviors, potentially indicating which fossils are female.
The study, led by Dr. Filippo Bertozzo from the Royal Belgian Institute of Natural Sciences, suggests that the observed injuries may occur during courtship rituals. “This will be a game changer since it will enable other questions to be answered about differences between male and female dinosaurs,” Bertozzo stated.
Identifying a pattern in fossils
The research originated from observations made by Canadian paleontologist Darren H. Tanke, who identified similar injuries on hadrosaur bones discovered in Alberta during the 1980s. Initially hypothesizing that these injuries were caused by male dinosaurs mounting females, earlier claims were largely based on limited fossil evidence. Bertozzo later noticed similar damage on a hadrosaur specimen in Russia during a 2019 research trip, prompting a collaborative investigation.
To substantiate their claims, Bertozzo and Tanke, alongside their research team, analysed nearly 500 hadrosaur tail vertebrae specimens from museums across North America, Europe, and Russia. They noted that the injuries found were remarkably consistent across different species, suggesting a common behavioral root.
“At the base of the tail, neural spines show signs of breaking and reabsorption,” Bertozzo explained. “This pattern was visible across several vertebrae for each specimen, indicating a repeated mechanism rather than isolated incidents.”
The suggestion posited by researchers is that male dinosaurs may have inadvertently caused these injuries while mounting females positioned on their sides during mating. Bertozzo reinforced that the mating hypothesis aligns best with the observed injury patterns across various hadrosaur fossils.
The study also highlights that the injuries appeared non-fatal, as signs of healing were evident, indicating that they were part of a normal reproductive behavior rather than a result of aggressive interactions.
Telling female from male
If confirmed, these findings could significantly enhance our understanding of hadrosaur sexual dimorphism. Bertozzo noted that such insights may allow researchers to analyze differences in features like skull crests attributed to sex differentiation, or dispel previous assumptions of new species based on anatomical variations.
However, the study’s findings are not definitive. Experts such as Dr. Yoshitsugu Kobayashi commended the research as imaginative but cautioned that while the modeling effectively ruled out alternative explanations for the injuries, it requires further evidence to establish conclusive links between the bone injuries and mating behaviors.
The pursuit to decode the lives of these ancient creatures continues as researchers aim to analyze fossils from other regions, such as China and South America, and leverage advanced simulations to provide deeper insights into the behaviors of dinosaurs.
Ultimately, the research signals a nascent understanding of dinosaur behavior and anatomy, with broad implications yet to be fully explored in paleontological study.
