Fish amphibians, reptiles, birds and mammals have similar embryos. They all start with gill slits, fish and some amphibians grow to have gills some amphibians reptiles birds and mammals developed lungs to breathe air. They all start with tails, fish, some amphibians reptiles and birds grow tails. Humans do not keep their tails, fish and reptiles developed skills. Amphibians birds and humans have skin birds have feathers and humans have hair, with which animal do humans exhibit the most linear relationship to? Birds, reptiles, fish, or amphibians?