What I get reading over the years is on land anything that couldn't crawl into burrow in the ground didn't make it. I think the answer with birds is they alrea

What I get reading over the years is on land anything that couldn't crawl into burrow in the ground didn't make it. I think the answer with birds is they already existed as separate species from dinosaurs. ""Birds evolved from theropod dinosaurs during the Jurassic (around 165–150 million years ago) and their classic small, lightweight, feathered, and winged body plan was pieced together gradually over tens of millions of years of evolution rather than in one burst of innovation. Early birds diversified throughout the Jurassic and Cretaceous, becoming capable fliers with supercharged growth rates, but were decimated at the end-Cretaceous extinction alongside their close dinosaurian relatives."" https://www.sciencedirect.com/science/article/pii/S0960982215009458 https://www.sciencedirect.com/science/article/pii/S096098221...