A feather found in dino poop and more...

It’s long been a mystery why one particular avian dinosaur was the only kind to survive mass extinction, but the recent discovery of a perfectly preserved fossilized feather, found in a cherry-sized piece of dinosaur poop, offers new clues. Also today: Why citizen scientists buried thousands of undies How climate change tipped the scales on a catastrophic Himalayan avalanche Why an AI leap has left mathematicians feeling uneasy Why scientists put teeny-tiny micro-trackers on chimney swifts