What are the two groups of therian mammals?
dolphins and whales
felines and canines
monotremes and mollusks
placental mammals and marsupials
Therian mammals are viviparous. They give birth to an embryo or infant rather than laying eggs. The female reproductive system of a therian mammal includes a uterus and a vagina. There are two groups of therian mammals: placental mammals and marsupials.