From Bob Clampett's "The Bashful Buzzard" (1945) You won't like this dragon when he's angry. Not only does he suddenly grow himself some teeth, but his head changes shape and size! It's not like we actually see his head changing on-screen... but Beaky Buzzard doesn't recognise the "mean" face when the dragon starts growling at him (0:58-1:08), so we have to assume either a) the dragon's head changed off-screen or b) Clampett assumed his audience would forget that they and Beaky had seen the "turtle" face a few seconds ago. (0:25-0:45)
By the way, anyone know where those "bringing home a baby bumblebee" lyrics orginated? Apparently there's a girl guides / girl scouts song with the same tune and the same lyrics, followed by "I'm squishing up / licking up / bringing (or barfing) up / sweeping up my baby bumblebee"... I wonder if this version predates or postdates Clampett's use here.