Bird cognition freaks me out.
Vertebrates only date back to 525 million years ago, and amphibians to just under 400 million years ago. The synapsids from which we mammals sprang date back to about 325 million years ago, while the diapsid ancestors of birds and dinosaurs split from us 300 million years ago. And yet birds can learn words. Like large brained mammals, several hundred words are not beyond exceptional birds like the late Alex the Gray (d. 2007). How!? And for that matter -- why are WE the weird mammals that blew through the several hundred word limit shared by cetaceans, elephants, and other other apes!? (Even dogs can learn over a hundred, and they have the social / pack intelligence / cognitive ability to figure out a lot of things we hypersocial Hominini do.)