Pronunciation: [θˈi͡əɹɪə] (IPA) 
The word "Theria" is spelled phonetically as /θɪərɪə/ in IPA. This term refers to a subclass of mammals that give birth to live young, as opposed to laying eggs. The spelling of this word includes the letter combination "th" which is pronounced as a voiceless dental fricative /θ/. The letter "i" is pronounced as a short vowel /ɪ/ and the letter "e" is pronounced as a schwa /ə/. The second "r" is silent in this word.
Theria is a taxonomic infraclass within the class Mammalia, encompassing the majority of modern mammal species. The name Theria originates from the Greek word "therizo," meaning "beast" or "wild animal," referring to the diverse and abundant nature of mammals within this group. Members of Theria are characterized by their viviparous mode of reproduction, in which offspring are developed within the mother's uterus and are subsequently born live.
Theria can be further divided into two subclasses: Eutheria, also known as placental mammals, and Metatheria, which includes marsupials. The distinguishing factor between the two subclasses lies in the development of the young. Eutherians give birth to fully developed, relatively mature offspring, while metatherians give birth to relatively underdeveloped young. In most therian mammals, the young depend on their mother's milk for nourishment through specialized mammary glands.
The diverse range of species within Theria includes mammals of various sizes, shapes, and behaviors. From tiny shrews to massive elephants, from marine dolphins to aerial bats, and from insectivores to herbivores and carnivores, Theria encompasses an incredible array of mammals. Their adaptability to various ecological niches has allowed them to thrive in almost every terrestrial and aquatic habitat on Earth.
Theria is a crucial group within the animal kingdom as mammals play significant roles in ecosystems and exhibit remarkable levels of intelligence, social behavior, and physiological adaptations. Studying Theria helps unravel the intricacies of mammalian evolution, behavior, and adaptation, providing valuable insights into broader aspects of biology and ecology.
The word "Theria" is derived from the Greek word "thēr", meaning "beast" or "wild animal". In scientific classification, it is used to refer to a subclass of mammals that includes placental mammals, excluding monotremes (egg-laying mammals) and marsupials. The term was first coined by the British anatomist Richard Owen in 1866 when he was establishing this mammalian subclass.
