Playing around some more, I decided to go for nearly the smallest creature possible (that still looks like a creature). Introducing...
"Perhaps one of the smallest creatures to crawl upon dry ground."
He doesn't look very scary. Quite the contrary in fact; he looks like he should be packaged up and sold as "bite-size" treats to carnivores and omnivores. However, should Tiny somehow survive Creature stage and make it to Tribal stage, he can look very formidable (if not a little... well... tiny) indeed!
Ha! I just noticed that Tiny is so tiny that he's the same size in the thumbnail image as the higher-resolution screenshot, which is zoomed in as close as the game will allow. Compare that to how much of the screen Masticanalis takes up in the larger images.
EDIT: Fixed spelling error and formatting problems.