Birds are total evolutionary powerhouses. There is no continent on Earth that they have not colonized, and they are frequently the keystone species of their ecosystems. When you consider their ancestry, however, it's no surprise that the bird family is so unapologetically kickass. These high flyers can trace their lineage back to the theropod dinosaurs of the Mesozoic, especially the nimble guys like the Compsognathus pictured here. So the next time you order chicken, show a little respect, because that's T-Rex's little brother you're eating.