Among the best inventors of metamorphic sequences was a Victorian artist named Charles H. Bennett (1828-1867). He was more generally known for comic illustrations, such as those for children’s books. He's worth looking into.
Above and below are examples from a series of metamorphic images that were initially published weekly in The Illustrated Times (c1863) as Studies in Darwinesque Development, which was later republished posthumously in a book titled Character Sketches, Development Drawings and Original Pictures of Wit and Humor (1872).