@Background Pony #EC55
If I’m a pony or alien or what have you who comes to Earth for the first time and I see a man with black hair and two women with red hair, is that conclusive evidence that human males have black hair and human females have red hair?
Regardless,
did we know which parent was which? If we’re talking about bird sexual dimorphism, phoenixes resemble eagles most closely, and in birds of prey – eagles, falcons, hawks and the like – the female is always bigger than the male, often substantially so. If all I’ve seen before is one specimen, the most obvious conclusion based on what I know about birds is that the bigger specimen is the mother. Now that conclusion is much less likely because it’s only
possible that female are bigger, but I know for a fact that I’ve seen a female with one type of crest and a male with another and that lets me make some predictions.
The point I’m trying to make is that no, it was not obvious that head crest differences are reliable and consistent signs of sexual dimorphism in phoenixes when all we had was one female and two others of indeterminate sex.