The amniotes are a group of tetrapod vertebrates that have a terrestrially adapted egg. They currently include mammals (synapsids), and sauropsids (reptiles, including turtles and birds), as well as their fossil ancestors. Amniote embryos, whether laid as eggs or carried by the female, are protected and aided by several extensive membranes. In eutherian mammals (such as humans), these membranes include the amniotic sac that surrounds the fetus. These embryonic membranes, and the lack of a larva… (More on Amniotes)