Thank you for the disclaimer about pterosaurs!
I read the "Love Among the Dinosaurs" article, and it struck me that perhaps some dinosaurs may have been parthenogenetic. Obviously, this would not have been widespread; asexual animals tend not to evolve as quickly, and they often inhabit marginal environments. Eliminating the need for mating would make the problem of those ornaments moot.
The trouble with my line of thinking there is that those same ornaments that make mating difficult are often thought to have been there in the first place for reasons of sexual selection...though with some groups, such as ankylosaurids, it's a valid conjecture.