OtherEric, Kelly fan Supreme, had the great presence of mind to remind us of Kelly's first foray into Prehysteria, called appropriately Prehysteria, and the scans presented here are courtesy of him. First presented in Animal Comics #21, way back in the 40s, it displays some nascent Kute Kelly Kritters in fore and backgrounds. It shows us that this story arc may have been bouncing around in Kelly's mind for some time.
OtherEric has scanned and shared some nice Kelly comic book stories over at goldenagecomics.co.uk where you can find a great (complete!) run of Animal Comics and Fairy Tale Parade, as well as a ton of other great golden age comic stories.