Beast of Hollow Mountain_pt.1 of 2

(1956) An Americano rancher down in Old Mexico finds the locals have a mighty peculiar varmint preying on their cattle. The idea for the screenplay came from effects pioneer Willis (KING KONG) O'Brien, but the special effects were handled by Edward Nassour, who alsoco-produced (with brother William), and co-directed (with Ismael Rodriguez.)

This US/Mexico co-production [aka "El Monstruo de la Montaña Hueca"] predates Ray Harryhausen's VALLEY OF GWANGI by a dozen years, again with Willis O'Brien earning writing credit. Who knew there was an entire sub-genre of "dinosaur westerns"? (Willis, evidently.)