Filmed in both English and Spanish at Churubusco Studios in Mexico City, the American version of this Willis O’Brien (the animator of King Kong) was called The Beast of Hollow Mountain while the Mexican one was named La Bestia de la Montaña.

Cowboys and dinosaurs seem like a pretty natural combination. In this one, Jimmy Ryan (Guy Madison, who played Wild Bill Hickock on TV’s The Adventures of Wild Bill Hickok) finds out that some real life giant lizards are eating all his cattle.

You know how I always complain about movies showing the monster too soon? This waits nearly an hour before you see the dinosaur. That’s having patience. Oh yeah — don’t get attached to the little kid who has an abusive father.

O’Brien also wrote another unproduced script from this concept called The Valley of the Mists, which would later be made as The Valley of Gwangi by Ray Harryhausen, in case you can’t get enough stop motion monsters.