http://www.sciencemag.org/news/2018/05/quaillike-creature-was-only-bird-survive-dinosaur-killing-asteroid-impact

This artist’s reconstruction depicts the kind of bird likely to survive the asteroid’s fiery aftermath.

Scientists have long wondered just how many birds survived the asteroid impact that wiped out the rest of the dinosaurs some 66 million years ago. Now, they may have their answer: very few, mostly small ones. A new study suggests that widespread forest fires made it impossible for tree-dependent birds to survive, meaning the vast avian diversity of today likely arose from just a few ground-dwelling survivors.