All of these skulls are from white-tailed deer, but
there are a lot of differences in the size and shape of skulls and antlers.
Some, like the skull here, don't have any antlers at all.
The size of the skull and
the antlers are related to the age of the animal when it died.
Younger animals had smaller skulls and smaller antlers.
But what about the skulls without antlers?
Well, antlers are only found on male deer, so
skulls without antlers are either from females or
sometimes from young individuals that never developed antlers before they died.
There are three kinds of intra-specific variation represented by these skulls.
The first is individual variation, which is the normal variation you see
among individuals of any species, things like the exact shape of the antlers.
The second is ontogenetic variation, or variation because of age and
growth, like the size of the antlers.