cómo explicas que, si no hemos visto un dinosaurio, no hemos viajado al espacio exterior, ni hemos visto un corazón o un cerebro humano directamente, aun así, podemos describir y hasta explicar el funcionamiento de estos sistemas

genetic variation will increase because of a new habitat and food source.

explanation:

fumikage isn't really a bird, and tsuyu does have teeth. tsuyu has a transformation quirk which still allows her to be partially human. otherwise we'd have a large frog running around. fumikage has teeth because again, he isn't a bird. his head was a quirk mixture if i'm correct.