Yes, the short answer is, it was an asteroid and the effects after that killed the (large, non-avian) dinosaurs. Other hypotheses do not have the same explanato

Yes, the short answer is, it was an asteroid and the effects after that killed the (large, non-avian) dinosaurs. Other hypotheses do not have the same explanatory power and may only account for a minuscule and much slower influence leading up to the asteroid extinction. Survival after the impact was greatly influenced by the simple ability to acquire food, but also other adaptations such as the immune system and ability to fight off fungal infections. Flying birds in particular had an advantage because they could forage for seeds over a vast distance while other terrestrial species run out of food (the article's cited study may broadly agree with this as an advantage, but suggests not as much post-chixculub diversification as believed before, and shows pre-chixculub modern bird form examples) There is a good YouTube documentary on the matter, but it is long: https://www.youtube.com/watch?v=6DHgkMYgp7w https://www.youtube.com/watch?v=6DHgkMYgp7w