Destiny, thanks for this second question. Interestingly it has connections to your previous question about evolution.
I asked my friends about unicorns.
The fact that there are no fossils does not mean that unicorns never existed. If you look at how modern humans evolved from apes there are a lot of gaps in our understanding, which could be linked to fossils that have not yet been found.
Where fossils have been found we can get lots and lots of information from them especially from the age of the rock in which they are found. This is to do with something called radioactive decay. This allows the fossils to be placed fairly accurately on the ‘evolution table’.
I have two immediate thoughts about unicorns. Firstly they are completely made up and secondly they are a brief part of an evolutionary story that didn’t survive. For example an animal (horse, deer, goat or other animal) was born with one horn by some biological accident, it lived but it’s children were ‘normal’ so the trait ended.
I prefer the mythical, made up model. I would like your thoughts.