Stegosaurus plates may have differed between males and females, providing an exciting way for scientists to determine an ancient fossil's gender and insight into their behavior.
The large herbivore that walked the Earth about 150 million years ago boasts two rows of bony plates running along its back, PLOS reported. Scientists observed that some Stegosaurus skeletons had tall plates, while others' were much wider that were 45 percent larger than the tall plates.
In this study the researchers looked at a group of Stegosaurus mjosi with varied plates that were discovered in a dinosaur "graveyard located in central Montana. They determined the differences in plate size did not indicate two different species, but rather was a characteristic of gender. CT scanning and microscope analysis of the ancient back plates ruled out growth as the cause of the variations because the bone tissue had reached maturity in samples from both varieties. The new insight could lead to breakthroughs in our understanding of Stegosaurus behavior.
"As males typically invest more in their ornamentation, the larger, wide plates likely came from males. These broad plates would have provided a great display surface to attract mates. The tall plates might have functioned as prickly predator deterrents in females. These stegosaurs seem to provide the first really convincing evidence for sexual dimorphism in a dinosaur species (excluding birds, which are technically dinosaurs themselves)," said lead researcher Evan Saitta, from the University of Bristol.
The findings were published in a recent edition of the journal PLOS ONE.