How is a chorioallantoic placenta different from a choriovitelline placenta? Give an example of an animal or group of animals that depend on each. How is a chorioallantoic placenta different from a choriovitelline placenta? Give an example of an animal or group of animals that depend on each. Solution 1) The family Peramelidae/bandicoots has a chorioallantoic placenta. The rest of the marsupials have a choriovitelline placenta. 2) The choriovitelline placenta is less vascularized than the chorioallanoic placenta. The portion in contact with the uterine lining is convoluted to increase the surface area in contact with the uterus but it is not deeply imbedded in the uterine lining. A small amount of uterine milk diffuses from the uterine tissue to the fetus, but most of the nourishment for the fetus comes from the yolk sac. 3) The chorioallantoic placenta is more highly vascularized. The fetal and maternal tissues are more highly interconnected due to the many finger-like projections known as villi that grow into the uterine lining. Gases and nutrients diffuse from the maternal capillary beds, across the placental membranes and into the fetal capillaries, and vice versa..