istukkaalliset

Istukkaalliset is a Finnish term that translates to "placental mammals." This classification refers to the infraclass Placentalia, a group of mammals characterized by a placenta that nourishes the developing fetus during pregnancy. This internal organ allows for a longer gestation period and a more complex development of the fetus within the mother's uterus compared to other mammal groups like marsupials and monotremes.

Placental mammals represent the vast majority of mammal species found today. Their evolutionary success is often attributed to the advantages provided by the placenta, enabling offspring to be born in a more developed state, increasing their chances of survival. This group includes a wide array of familiar animals, from humans and dogs to whales and bats, showcasing a remarkable diversity in form and habitat.

The defining feature, the placenta, is a temporary organ that develops in the uterus during pregnancy. It facilitates the transfer of nutrients and oxygen from the mother to the fetus, and the removal of waste products. This symbiotic relationship is crucial for the intricate development of complex organ systems before birth. The existence of the placenta is a key evolutionary innovation that has contributed significantly to the diversification and dominance of placental mammals across the globe.