Dragons, Why can't we find them?

The reason we can't find any dragons is very simple. They can look human. Yep in lots of books I've read the dragon can simply look human when they want to. Although I have yet to see why we haven't found dragon bones since they don't automatically change into human form when they die. The only thing I can think of for that is that they look like dinosaurs. You're probably thinking what about carbon dating. Well you see dragons are very long lived so their bones read as so old that they look to be the right age in carbon dating. So that is why we can't find dragons. Now I just need to work on why we can't find the Lock Nes Monster.