I'm especially curious about older crests. I know lions had a much larger home range before extending across North Africa into Turkey and across lower Greece. It seems like an animal that would not be collectively known by the average European after the Romans and not again until exploration and the sciences re-emerged. Yet, medieval backwater peasant towns in France and even countries like Sweden (getting as far away from lion territory as possible) have lion crests. Is there some historical precedence for this, did they simply like the design or grandiose associations of lions, or am I wrong entirely and they have always known what lions were? Thanks
Folks in the Middle Ages of Europe were quite aware of what lions were. Sort of like how folks in the United States don't exactly live anywhere near the natural range of Snow Leopard, Komodo Dragon, or King Cobra--and most of us have probably never seen one in real life unless a local zoo happens to have one--but we still know what they are and what they look like.
There is an FAQ section on this question
https://www.reddit.com/r/AskHistorians/wiki/faq/europe#wiki_lions_in_european_heraldry
What about griffins and unicorns, did people think they are real when using them on heraldry?