Eutherians, also known as placental mammals, are a group of mammals characterized by their complex placenta, which allows for a longer gestation period. This adaptation enables the developing young to receive nutrients and oxygen directly from the mother, leading to more advanced offspring at birth. Examples of eutherians include humans, dogs, and whales. Eutherians are distinct from other mammalian groups, such as marsupials and monotremes. They make up the largest group of mammals, with diverse species adapted to various environments. Their evolutionary success is attributed to their reproductive strategies and the ability to nurture their young effectively before birth.