Q. Are the extraembryonic membranes the same in all vertebrates?
The presence of each extraembryonic membrane differs according to the vertebrate class.
In amphibians and fishes only the yolk sac is present. In birds and reptiles besides the yolk sac there are also the allantois, the amnion and the chorion.
In placental mammals as well all these membranes the placenta is present too.