An unnamed narrator tells a story about the history of Texas set one million years ago, when Dinosaur Dan, the eponymous villain, terrorized the state. He rustles all the cattle (brontosaurs with the heads of Texas longhorns), and runs off with all the pretty women. The primitive Texans finally corner Dan in his mountain hideout, and cleverly chisel away the outer rock, leaving behind a small rock jail with Dan inside. The final scene shows the jail still standing in modern day Dallas, and reveals that the narrator is really Dangerous Dan, still in jail and sadly asking "When are y'all gonna let me out of here?"
Ed Benedict provided uncredited layout designs for this cartoon. Benedict would later work for Hanna-Barbera Studios (which was started by MGM alumni William Hanna and Joseph Barbera), where he would use some of the caveman designs from this cartoon as the basis for characters in The Flintstones.