Dinosaur horns may have been part of the mating game, or maybe not

Despite the screaming headlines on the BBC site about Triceratops developing horns to attract a mate, the study's actual conclusions are slightly different.

If sexual selection is indeed the process behind the unique ornamentation of ceratopsians, it points to a set of conditions acting upon ceratopsians without obvious parallel in extant taxa. ... Some support has been found for this in the positively allometric growth patterns of the ceratopsian Protoceratops, and the patterns of ornament divergence seen in Ceratopsia are similar to those seen in the sexually selected horns of the scarab beetle genus Onthophagus .

If you want the full paper, it's here: Patterns of divergence in the morphology of ceratopsian dinosaurs: sympatry is not a driver of ornament evolution