Spec-Dinovember Day 4: Your Wildest Dream, a wild speculative behavior that left no fossil trace
Nearly every extant horned animal keeps their horns for their entire life. Deer grow and shed their antlers every year, though antlers are developmentally and structurally very different from horns. But, there is a singular outlier, the Pronghorn! Pronghorn have horns with deciduous sheathes, and moreover the bony core of the horn has similar texture to those of regular horns. So maybe, just maybe, some ceratopsians bore similarly deciduous sheathes!
------------------------------------------------------------------------------
This isn't a behavior per se, but I think it's a pretty wild speculation so I ran with it! I couldn't find much on how pronghorns grow their sheathes (how do they grow the prong?) except for sources more concerned with hunting. Though one of these informed me that the distal curve grows for ~8 weeks, then the straight proximal portion grows for another ~12 weeks. So, I stacked the outline of the horncore 20 times to get the shape of the full sheathe. Also the roughened area anterior to the orbit and below the horncore lined-up nicely for a justifiable place to grow the 'prong' from. In some centrosaurines this area has correlates for a single large scale, though it seems centrosaurines and chasmosaurines may have differed in facial integument, and some ceratopsids lack this rough area entirely so... plenty of space to play around with weird structures! I don't think this is a likely reconstruction, but there is a *very* slim chance it is possible, and that's pretty fun!