This trope is about the fact that some of the animals on the same end of the Sliding Scale of Anthropomorphism are more likely to stand upright and others are more likely to stay on all fours. In other words, it is about one animal on two legs and an animal on four legs being close to each other on Sliding Scale of Anthropomorphism. It's not always a case that the two-legged characters are more intelligent or more "humanized" than the others, but the Trope Namer, Animal Farm, and the trope's name suggest this case. Subtrope of Funny Animal Anatomy. Examples: