Do you know which of these two bird is the male, and which is the female?
Peacocks are relatively easy to tell apart, as the males have
elaborate feathers and coloration that sets them apart from females.
The proper terminology for this Sexual Dimorphism.
All this means is that the males and females look different.
Even among humans, it is typically easy to tell the difference between a male.
And a female.
Although human males don't take this to quite the extreme that a peacock does.
So some things are relatively obvious when it comes to sexual dimorphism.
In these peacocks feather coloration is one of
the most obvious things we can think of when it comes to dimorphism.
However there are a lot of other ways that dimorphism might manifest itself.
For example, we see that in male hoofed animals such as moose and
most other deer grow enormous antlers shortly before mating season.
There have been many proposed cases of sexual dimorphism in dinosaurs.
But so far almost all of them have been fairly ambiguous.
Male and female ceratopsians, for
example, have been suggested to have different horn shapes and sizes.
However, because many ceratopsians are known from single specimens,
it becomes hard to say anything definitive about sexual dimorphism.