March 14, 1952: He's not THAT snoopy

Snoopy's appearance has been gradually progressing all this time, but this strip seems like one of the more obvious changes.

The later jokes of Snoopy acting a lot like a person, and being treated like one, evolved out of gags such as this one. When Snoopy has been half-human for twenty years it is hard to get humor out of his doing things not expected of dogs, or being treated as human.

Really, what could the girls be so defensive about? They're, what, six?

October 25, 1950: Dogs are indiscreet

Snoopy is just too adorable in these panels.  A few months later Schulz will make pretty much the opposite joke in relation to Charlie Brown's diary.