From the Game's Introduction:
Cowboys and Dinosaurs (C&D) is the role playing game of the little told story of the old west and how natives, sheriffs, cowboys, mad scientists and their companions struggled to make a place for themselves. This RPG is written with experienced role players in mind, for the 2011 RPGGeek.com 24 Hour design contest. It assumes a group of 3-6 participants, with one taking the role of Game Master (GM).
The game is played with pencil and paper to record characters, notes and other game developments and a deck of cards participants for resolution of events. Use one deck with 3-4 participants and a double deck if there are 5 or more at the table. The setting is intended to be campy, but gritty. Despite the impressive strength of the dinosaurs, they remain dangerous beasts, not easily tamed.