It’s got nothing to do with preconceptions, and everything to do with not being taken for a ride. This may come as a surprise but if you see a dog’s face in a cloud,
the dog’s not really there.
You want to see a dinosaur, so what is plainly set before you is a dinosaur because that’s what you want to see. But wild boar regularly walk over my hill farm and what is plainly set before me is a wild boar.
What right have you got to tell others what to see? The obvious thing to do, well it’s obvious to most people, is get past our own prejudices and ask what is likely, could it be something else, perhaps pure imagination, a Cambodian equivalent of Godzilla? Rather than just lazily accept the first thing that pops into our head, we do some research.
So: paste the image location into a search engine such as
tineye.com/ to find all the websites showing the image, then look at some of them. In this case I clicked the first hit,
paleo.cc/paluxy/stegosaur-claim.htm, which turned out to have a reasonable discussion of the claim that it’s a dinosaur. From this alone it seems to me that there’s no chance it’s a stegosaurus.
You can believe different, but don’t be surprised if others won’t accept your authority when you tell them to look at a tiny photo from the internet and believe the first thing that pops into your head.
If you look more closely at the supposed Nile mosaic of Palestrina image, you will see lettering across the top. I don’t understand Greek, but it is said to read “crocodile-leopard”. So the artist himself called it a crocodile-leopard, whatever you think is plainly set before you.