Welcome to the forum! Your thread was sent by the system for moderation, as there were two disguised links - in the words "unicorn" and "flying horse". I have removed these links and approved your post.
Regarding unicorns, yes, they did exist in the long past, but not in the form they are often described. See http://www.goodhousekeeping.com/life...-real-fossils/
The chollima is, however, strictly fictional. To answer your other queries, a red dragon is the national symbol of Wales and the dinsoaur is not used as a national emblem. You will find a full list here: https://en.wikipedia.org/wiki/List_of_national_animals
Please go to the introduction section of this forum to say hello to members and tell them about yourself and your interest in animals.