The Ghost of Slumber Mountain

The Ghost of Slumber Mountain is a 1918 film written and directed by special effects pioneer Willis OBrien, produced by Herbert M. Dawley, and starring both men Dawley played Uncle Jack Holmes, while OBrien played the ghost of Mad Dick the Hermit. It is the first movie to show live actors and stopmotion creatures together on the screen. Although most of the film itself is lost, it is often cited as a trial run for The Lost World.

In the version available today, Holmes Dawley is telling his nephews about an adventure he had in the woodlands around Slumber Mountain, near the Valley of Dreams. He finds the cabin belonging to the late hermit Mad Dick, who Holmess friend Joe once saw carrying a strange telescopelike instrument. That night, Holmes searches the cabin and finds the instrument. Upon doing so, the ghost of Mad Dick OBrien instructs him to use it to look at the peak of Slumber Mountain. When he does, he seemingly looks back into the past, seeing a Tyrannosaurus and a Triceratops doing battle. The Tyrannosaurus proves triumphant, and after killing the Triceratops, somehow breaks the time barrier unless the instrument does that itself and begins chasing Holmes.

Source: Wikipedia