In addition, for a long time, a unidirectional flow of air through the lungs was considered a character unique to birds: all birds had it & no animals other than birds did. But a recent study found that alligators also have unidirectional flow of air through the lung! Further, we have found fossils of extinct reptiles - dinosaurs - that show they had unidirectional flow of air through the lungs, with accessory air sacs, that protruded into partially hollowed-out bones.
And the old problem about digit identity has been solved by embryonic studies, which showed that a shift in Hox gene expression transformed the digit identities.
HUMANS
Human embryos form a postanal tail! Unlike the vast majority of vertebrates, including fish, humans don't have tails (& neither do chimps, bonobos, gorillas, or orangutans, our 4 closest living relatives!), yet we form one in embryonic development, just to have it largely resorbed & fused to form our coccyx.
Human embryos also start off with the eyes on the side of the head, like the eyes of adult and embryonic fish; our eyes must migrate toward the front of the face to end up in the human-appropriate location.
Human embryos also start off with a very fishlike arrangement of aortae & aortic arches, which then require much remodeling to arrive at an arrangement appropriate for humans. Also, human embryos form fishlike pharyngeal arches, & even pharyngeal slits transiently. The embryos of humans – placental mammals – also have a vestigial yolk sac.
Then there's genetic evidence all over the place.
HOX GENES
Fruit flies have a series of Hox genes along a chromosome that helps pattern their anterioposterior axis during development, with the linear location of the genes along the chromosome matching the linear body regions they affect. Turns out that mice, humans, fish, & other vertebrates also have Hox genes, arranged in the order along chromosomes that correspond to the regions of the embryo they affect.