Muybridge was a nature photographer commissioned by the Governor of California, Leland Stanford, to document his mansion and possessions. Stanford posed an exciting challenge to Muybridge: could he take clear pictures of a galloping horse?
1872 was the year that Muybridge began his zealous involvement with motion photography. He was commissioned by Governor Leland Stanford to photograph the moving gait of his racehorse, Occident. Until this time the gait of a moving horse had been a mystery. When did the feet touch the ground? Did all four feet ever leave the ground at the same time? Painting the feet of the galloping horse had been an unsolved problem for artists. … [He used] 12 cameras, each hooked to an electrical apparatus that would trip the shutters as the horse galloped past. … Muybridge invented the zoopraxiscope in 1879, a machine that allowed him to project up to two hundred single images on a screen. In 1880 he gave his first presentation of projected moving pictures on a screen to a group at the California School of Fine Arts, thus becoming the father of motion pictures.- Vi Whitmire 
And Muybridge didn’t just take pictures of moving horses. He created similar sequences of moving cats, dogs, buffaloes, ostriches, people, etc.