Did ceratopsian frills evolve for species recognition?

[Halichoeres]

If ceratopsian frill diversity evolved partly because the ability to discriminate among species visually favored survival or reproduction, we would expect frill traits to be more labile, particularly in sympatry, than other morphology. This paper finds that they don't show such response to sympatry:



That doesn't mean they couldn't still have been sexually selected, just that there doesn't seem to be an effect of sympatry.

Paper (open access): http://rspb.royalsocietypublishing.org/content/285/1875/20180312

[Soopairik]

Possibly, but the primary use was most likely for defense of the solid-frilled ceratopsians.