For reasons I wont go into here, my duck flock was living at my brothers house. One day he had some friends over and while they were sitting outside they saw something come running into the yard, grab a duck and run off. When I arrived, 7 adults described the animal to me in very good detail.
I couldnt believe what they were describing. I went and got a picture of what I thought they described and showed it to them. All of them swore that what I showed them is what grabbed my duck. This is the point that I told them that thylacines were believed to be extinct and never lived in Northern Wisconsin. The confused looks on their faces said that they honestly thought they had fingered the right creature. I decided that it was probably just some sickly stray dog.
In other words, eye witness accounts just arent worth much.
There is a flying creature that appears in some of that alien world fantasy art stuff that looks something like a sting ray but the wings are those of a bat and the tail is a fat snake trailing behing the body...ever seen the art?
Imagine my surprise when I saw one. The sky was a cloudy light grey, the lake a dark grey and the beast appeared black. I searched for the smallest detail but couldnt see anymore detail and I stared at as it approached but just couldnt figure out what it was.
Eventually it flew nearby in front of me, over land, and thats also when a break in the clouds appeared. I was looking at a bald eagle carrying a large and long pike type fish.
There is a site full with weird creatures people thought existed in the middleages, and an explanation for what they most likely where.
Don't know the link from memory,
but there are really good examples. The coolest is, they point out that many people in those days already suspected a mythological monster here and there to be a normal animal which got mangled after described to an artist.
They have far out pictures of monsters that are really crocodiles or eliphants. Did you know that the unicorn got into existence after someone failed to describe a hippo correctly? Some person described it as being like "a horse with a horn on it's head". So that's what the artists drew, the picture got into peoples imagination and suddenly people begin to saw the darn thing everywhere!
I guess people in the dark ages wheren't too mentally different from nowadays. We are just all cavemen with technology.