[tlb]

The Indian image seems to me to be more likely a buffalo type animal. You don't offer a date for the image but a post-Spanish Texas Longhorn seems possible too. Here is an image of a Stegosaurus. Note, no head horns and a very small head. I presume you call it a Stegosaurus based on the bumps along the back. No idea what the artist meant them to be, but Stegosaurus dorsal plates were huge relative to the head, as you can see. The drawn horns are not Stegosaurus tailspikes since you can see the feet are clearly pointed toward the head and horns. Yet another problem is if there were dinosaurs in historical times, where are the fossils ? In nearly two centuries of archaeology, somebody should have found something so odd and out of place.

[NativeSon]

Yet another problem is if there were dinosaurs in historical times, where are the fossils ?

The general consensus on fossilization is that it is quite rare and dependent on multiple environmental and geologic conditions to play together in specific ways. It also takes a long time in human scale

[HereInTheHeartland]

What would have prevented Indians from seeing dino fossils and incorporated those images into their paintings?

[wendy1946]

The horns in the petroglyph at massinaw were added at a much more recent time. Amerind oral traditions describe the water panther as having red fur, a sawblade back, and a “great spiked tail” as the glyphs show. No modern animal has a sawblade back or a spiked tail.

[Ha Ha Thats Very Logical]

if there were dinosaurs in historical times, where are the fossils ? In nearly two centuries of archaeology, somebody should have found something so odd and out of place.

It's also awfully convenient that they survived long enough for American Indians to have seen them and still be scared of them when Lewis and Clark went west, but no European explorer or settler ever ran into one.