"Look, I'm not saying that they definitely exist. I'm just saying that they might exist, or at least might have at some point."
"Well, the same thing could be said for sasquatch or elves. They might have existed at some point, theoretically, but we generally assume that they didn't, for lack of evidence."
"Right, but those were always anthropomorphizations. I'm talking about something quite different, something much closer to other extant lifeforms."
"Well, you don't believe in unicorns, right? So why would you believe in deer?"
"Well, a unicorn would be unexpected. It's only supposed to have one protrusion, centered, but with an asymmetrical twist to it. That's not to mention all of the mystical properties ascribed to it."
"Aren't these alleged deer a bit mysterious, too? They have these big, branching horns coming out of their heads, but they're supposed to live - or at least have lived - in forests? And they could disappear for extended periods of time, even in areas purported to lack caves? And why hasn't anyone seen one since ancient times, anyway?"
"Well, that's why I'm open to the idea that maybe they once existed, but don't any more. And as for the other things, well, stranger things have been found to exist in the fossil record. Plus, it's not like every single thing from the old stories will turn out to be true. Remember Chiroptera gargantum? They turned out to be real, but without those short, useless forelimbs that they allegedly had."
"I wonder if the head-ornaments will turn out to be the same way. After all, not all accounts of deer include those. ... Well, when you get right down to it, we can't confirm that they existed until we find a specimen, living, dead, or fossilized. Still, I don't even know of any path that might lead to such a thing. It sounds more to me like something that was invented back in the day when humans were still trying to pilot vehicles manually. They provide a good excuse for accidents, don't you think? They're a bit like Disney lemmings in that regard - suicidal, but not enough to make them extinct."
"Yeah, that behavior does seem a bit silly. That's probably the best evidence that deer never existed, after all."
NOTE: Holy crap, I totally forgot about this one. I started it back in February, apparently. Well, at least it's finished now.