Although these battle reports don’t specifically deal with cowboys, they have dinosaurs romping around various battlefields.
Safari On Venus
I’m just going to jump to the best one, which is the Safari on Venus. Terrific alien scenery, great Lizardmen conversions, and an appearance by the old Papo T-Rex toy (you might remember him from my own Great T-Rex Hunt).
Anyways the first link has more of the play by play while the second has slightly clearer pictures:
I had actually heard about Saurian Safari way, way back, but only recently remembered it as a comrade in arms to the great “add dinosaurs to improbable scenarios” genre. Think of it as rules to play out The Lost World by Conan Doyle. Except remember that his book was written in 1912 and the Victorian Era was only a decade old. The work must have been mindblowing at the time. Anyways Saurian Safari let’s people play out a dinosaur hunt, and that’s exactly what this battle report shows:
(Note he degrades The Valley of Gwangi with: “the C movies crap, like the cowboys wrassling a T Rex in Valley of Gwangi”. My word, I’m getting the vapors!)
Of course once a person starts searching for “Saurian Safari” you find numerous other awesome photos and battle reports, such as this one about Pirates vs Dinosaurs on an awesome island layout (that really makes me think of Settlers of Cattan).
And just a quick mention (since the post doesn’t have many pictures) someone had an entry about The Lost Legion of Venus using the GASLIGHT rules: