The scientists have found that the male Stegosaurus used billboard-like back plates to sexually attract their potential female partners, while females possessed prickly spikes that helped them in keeping these predators at bay.

Stegosaurus was a class of large herbivore dinosaur that lived approximately 150 million years ago. It is famous for its two staggered rows of bony plates at its back.

According to the researchers, the current study offers the most convincing evidence to date that both male and female dinosaurs are different from each other in their appearance. This suggests that the dinosaurs may have had rituals for mating selection as compared to those of modern species like birds.

Evan Saitta, study researcher from the University of Bristol, said, “The discovery of sexual dimorphism suggests that the males were displaying. It gives us insights into dinosaur behavior.”

The researchers carried an anatomical survey of the back plates’ shapes from roughly five skeletons found in a Stegosaurus graveyard in central Montana, and plates from nearly six individuals uncovered elsewhere.

The study showed that some stegosaurus had sharp, tall plates, while others had wide rounded plates that were roughly 45 percent larger in surface area.

The researchers denied the possibility of existence of some spikier male or female stegosaurus than others.

“The 40 plates we looked at belonged to two distinct categories of shape without any real intermediates. It’s a stark distinction of wide versus tall. If it was normal variation you’d expect more of a bell-shaped curve,” Saitta said.

The analysis of other bones revealed more anatomical similarity of the skeletons.

The findings of the study were published in the journal PLOS One.