Protoceratops used their frills to flirt

[Eldorado]

Many dinosaurs had distinctive bony frills around their necks -- the best-known being the distinctive Triceratops.

It's not a feature found in living animals today, and paleontologists have long debated what the function was of the diverse array of frills and horns in this family of dinosaurs, called ceratopsians.

The large frill that skirts the skull of Protoceratops dinosaurs was more likely used as a signal to prospective mates -- rather than for defense or cooling their bodies, a new study has suggested.

These sheep-size dinosaurs lived around 70 million to 74 million years ago in what is now Mongolia's Gobi Desert.

Full article at CNN: Link

Three-dimensional geometric morphometric analysis of the skull of Protoceratops andrewsi supports a socio-sexual signalling role for the ceratopsian frill.

Royal Society

[Abramelin]

I think the first time someone suggested that was like some thirty years ago.