I'm not sure whether the joke is that dinosaurs went extinct but this guy doesn't know because he's from too far away and he's been seeing earth from millions of years ago, or because he's the comet that made them go extinct.
Pyle is hilarious, I remember when he first started with those alien comics. His shit really fits my sense of humor lol
He is like that cloud from disney short animation. Keeps hurting what he values, very sad indeed.