The Beast of Hollow Mountain

The Beast of Hollow Mountain is a 1956 Weird West movie about an American cowboy living in Mexico who discovers his missing cattle are being preyed upon by an Allosaurus. The Allosaurus would later attack local villagers in a town, and eventually be destroyed by getting lured into some quicksand and drowning.

In southern Mexico at the turn of the 20th century, tales are told of cattle and farmers mysteriously disappearing. These events occur at a location called Hollow Mountain where a curse is supposed to be residing. The mountain has never been explored and the swamp at its base is said to claim the lives of anyone foolish enough to go to its banks. In spite of these tales and possible perils, American cowboy Jimmy Ryan leads three cowboys into the area in search of lost cattle. When they arrive they find mysterious tracks and believe the curse from Hollow Mountain is responsible. Whilst trying to track the curse down one of them falls into a tar pit at the base of the swamp and nearly drowns, but is rescued.Back in town, Ryan meets a Mexican boy, Panchito, and his father Pancho, who own a large ranch out in the country, not far from Hollow Mountain. As the two are leaving to check on the cattle, a gang of young bullies throw firecrackers at them, causing Pancho to fall off his horse and get dragged across the ground. Ryan notices this happen and stops the horse saving Pancho. Afterwards he begins falling in love with the beautiful Sarita, who had also stopped to help Pancho. Ryan and Sarita head to the cafe of Don Pedro, an old Mexican who Ryan talks to about the disappearing cattle. Ryan says that it is becoming clear that cows dont jump into swamps and because the swamp is shrinking it is losing its deadliness. While the two are talking, Enrique, a tough old Mexican, comes by. Enrique does not want Ryan to ranch his cattle here because he says Ryan should just ranch in Texas where he came from. But since the selling prices are cheaper here ranching has become less difficult. The two almost fight but Don breaks it up. ........

Source: Wikipedia