Huge animals.

That, is one gigantic bird. I like how the other horses are also like WTF. Imagine coming across one of those during your casual lunch-break walk in the park or something.

It's funny that in the past there were all these huge animals, monstrous times.

The animals I find the most fascinating are:

Unicorns cause they have magic powers as proved by the anime "The Last Unicorn".

Dragons cause they fly and breathe fire and would give you a strong advantage in war as proven by that hot chick in Games of Thrones.

Also Phoenixes are fascinating cause they can be reborn from their ashes as proven by one of the Harry Potter movies.

I'm saddened I'll never know how delicious some of them might have been

There are multiple theories on why they died out. Most say it was them being replaced by sabretoothed cats, but there are also other theories that say they were already dying out before the cats came. Wolves coming to America from Alaska land bridge could also have caused their numbers to dwindle. Some of their prey could have also died out or become to fast for them to prey upon. Multiple factors are always at play.

The Dodo.

I like big mammals, like wolves and extinct lions

Humans are mammals and they can be considered big so does that mean you like humans?

Some female ones yeah :) 

Before worrying about the extinct ones, do you know how delicious all the currently living animals are?