Gertie the Dinosaur (1914)
McCay’s most enduring work, Gertie the Dinosaur was his primary contribution to what would become mascot-based personality animation that would inform everything from Felix the Cat to Mickey Mouse to the whole cast of LOONEY TUNES. The whole short was formatted to allow McCay to interact with his creation in his vaudeville act, commanding her to raise her feet or leave a poor little mammoth alone.
In fact, one of GERTIE’s overlooked aspects is its fostering of a prehistoric world of its own, basic as it is. We see a sea monster, a flying saurian, the aforementioned mammoth, and of course Gertie herself, who is a realistic yet irresistibly charming animal.