How old is dreaming?

"Since alligator tastes like chicken, what does chicken taste like? Dinosaur."

We dream, dogs dream, cats dream, mice dream: "the brain patterns were so similar they could tell what part of the maze the rats were "dreaming" of."

Apparently zebra finches dream too: "humans cycle between SWS and REM sleep roughly every 1.5 hours, but birds appear to do it every 10-15 minutes."

Maybe dreaming for memory consolidation is fundamental to animal brain design. Sleep is certainly important: "A good night's sleep improves young birds' ability to learn new songs". But, of course, "birds initially struggle to replicate and remember songs when they first wake up." They lack coffee.

What would a T-rex do first thing in the morning? Shake his head and mumble "Was I really such an idiot as to fight a triceratops in a thunderstorm? What is a triceratops anyway?"