Frilling discovery explains head crests in sexy dinosaurs

A new study shows that Protoceratops used its crest for sexual or social displays

The incredible array of horns, frills, helmets, crests and other generally excessive and unusual structures that adorn dinosaurs have been a puzzle to palaeontologists back to the earliest discoveries of these animals. Huge numbers of hypotheses have come and gone about what they might have been used for though recently one idea has (re)emerged from the pack - sexual selection and social dominance. This is the aspect of evolution that produces features like the train of a peacock or the antlers on deer - structures that essentially advertise the health and 'quality' of the bearer and help them find suitable mates and / or take a dominant position in a social situation.

This is an area of research I have been working on (and writing about) for several years but it's a frustrating issue as naturally the behaviour of long extinct species is rather hard to test. One productive line is that socio-sexual dominance structures typically only grow late in an animals' life. When they are young, their efforts are focussed on surviving and growing and getting to sexual maturity to reproduce, so growing large and heavy structures (or things that are brightly coloured and might give you away to predators) are eschewed. Then as maturity nears, these are important and suddenly grow quite quickly.