The title pretty much sums it up. Here, take a look at this piece recently done by Rodrigo Vega!
For the page it was posted on and to view more of Vega's art, click here: http://levergunner.deviantart.com/art/Chronomancer-s-Weird-West-529050734
This guy is an awesome artist and his stuff is well worth your time looking at! His style is like a combination of H.R. Geiger and Frank Frazetta.
I'm hoping to commission him myself sometime. Can you imagine him doing more dionsaurs and cowboys together? :D