Placentalia
Placentalia, or placental mammals, is a clade within the therians that includes all living placental mammals and their extinct relatives, excluding the monotremes and marsupials. Members give birth to relatively well-developed young after a prolonged gestation in the uterus, where embryonic development is sustained by a chorioallantoic placenta. The term reflects this shared reproductive strategy, but exact membership can vary with phylogenetic interpretation.
The clade comprises the majority of living mammal orders, including Primates, Rodentia, Lagomorpha, Carnivora, Cetartiodactyla, Perissodactyla,
Fossil evidence indicates that placental mammals originated in the Mesozoic, with the crown group Placentalia likely
Key features of Placentalia include viviparity with placental nourishment and extended gestation, followed by lactation after