“Gertie the Dinosaur” (1914) IMDb
In a live-action framing device, Winsor McCay makes a bet that he can make a dinosaur from a museum “live again”.
Following on from “How a Mosquito Operates” (1912), Gertie is the first animation drawn with systematic key frames and inbetweens, integrating physical impossibility and lively comedy (later the stereotypical animation genre) with appealing characterization as opposed to technical demo or formalism. Produced for display as part of a vaudeville act.
Drawn on paper, not a transparent material like the plastic cels that would dominate industrialized 2D animation a little later. The most amazing thing about the medium is McCay’s choice of fairly complex, geometrically irregular terrain in deep focus, implemented with tracing paper by an assistant, showing subtle variations (jitter) throughout the film.
The integrated image on rice paper, instead of cels layered over a background, allows McCay to manipulate the terrain in surprising ways that never happened in the mature industry, and which are still difficult in modern 2D animation software that retains a separation of background and foreground.
Animation could have gone in a very different direction from here. The setting and characters are whimsical compared to Jurassic Park (1993), but much more detailed and realistic than early Fleischer or Disney.