Pronunciation: [juːθˈi͡əɹɪə] (IPA) 
"Eutheria" is a term used in biology to refer to a group of mammals that give birth to live young rather than laying eggs. The spelling of "eutheria" is pronounced as [juːˈθiːriə] using the International Phonetic Alphabet. The word is derived from the Greek words "eu" meaning true, and "therion" meaning a wild beast or a beast of prey. The spelling is unique due to the combination of the letters "eu" and "th" in the same word.
Eutheria refers to a diverse group of mammals belonging to the taxonomic class Eutheria within the broader category of vertebrates. Often referred to as placental mammals, they are characterized by a unique reproductive feature known as placental viviparity. This means that their young ones develop inside the female's uterus, where they are provided with nourishment and oxygen through a specialized organ called the placenta.
Eutherians are the most successful and dominant mammalian group on Earth. They showcase an immense range of morphological and ecological adaptations, representing approximately 95% of all mammal species. These mammals exhibit a wide variety of sizes, shapes, and habitats, ranging from small, insect-eating bats to giant herbivorous elephants and marine-dwelling whales.
One of the key evolutionary advantages of eutherians is their well-developed placenta, which allows for longer gestation periods and a higher level of maternal care. The placenta facilitates the exchange of nutrients, gases, and waste products between the developing fetus and the mother's bloodstream.
The presence of a placenta has led to numerous benefits, including increased survival rates and enhanced adaptability. Eutherians have successfully colonized diverse environments, including terrestrial, aerial, and aquatic habitats, and have occupied various ecological niches worldwide.
Overall, eutheria represents a highly diverse group of mammals characterized by their ability to provide an optimal environment for their developing offspring through the presence of a well-developed placenta, enabling them to thrive in a wide range of habitats and ecological conditions.
The word "eutheria" is derived from the Greek words "eu" meaning "well" or "true" and "therion" meaning "beast" or "wild animal". Eutheria is one of the three major subdivisions or subclasses of mammals, comprising placental mammals that give birth to relatively developed young ones. The name "eutheria" emphasizes the advanced reproductive characteristics of these mammals compared to other groups, such as marsupials (which have a less developed form of reproduction) and monotremes (which lay eggs).
