It would not be right to go to Dinosaur and not see the world famous dinosaur bones discovery. The theory goes that there was a flood or sequence of floods and this river bend happened to collect the dead animals which got covered by sand and fossilized. The river bed was then turned on its side by plate tectonics. You can read more about it here : A shelter was built around the remaining fossils, which is now the museum.
What we get to see here is just a fraction (~1/6 ?) of the original cliff. Other pieces were sawn up and shipped to museums around the world. Still very impressive though, and somehow more moving when still connected to the earth. Especially when you can recognise the pieces of these beasts.
I'm not very good at identifying snakes, other than "hey look! SNAKE". I think this is a Glossy Snake ?