Love is in the air
Although many animals have males and females that look alike, many others, from salmon to deer to mallards, have very clear differences between the sexes. Pterosaurs were no different. We can't yet determine differences in coloration, but there are several species with different crests and significant adult size differences.
Comparisons to modern animals suggest that those with larger crests and bodies were males, as they tend to have larger and flashier ornaments when there are clear differences between the sexes. This has been confirmed in Darwinopterus, as a fossilized egg has been found with a crestless individual.
♂ 
♀ P. longiceps
♂ 
♀ P. sternbergi
Flashy crests and bright colors
These features may have helped male pterosaurs attract mates and intimidate rival males. In some living examples with large flashy males, like elephant seals, a few dominant males will control several females. This may have been the case with Pteranodon, whose males were much bigger than females.
The tale of two Pteranodon
Both species of Pteranodon are found in Upper Cretaceous rocks in Kansas, but they never saw each other in life. Pteranodon sternbergi lived about five million years before Pteranodon longiceps and may have been its direct ancestor. Like deer and elk, the females had smaller head ornaments.
Art by Franz Anthony.
