This article is about the subclass of mammals. For the use of the word "therian" as a synonym for "therianthrope", used predominantly in the context of modern subcultures, see "Therianthropy".

Theria (pronounced /ˈθɪ.ɹiː.ə/ from the Greek θηρίον, wild beast) is a subclass of mammals that give birth to live young without using a shelled egg, including both placentals and marsupials. They have external ears, can suckle on a nipple, and have an ankle specialized for power and range of motion. Therians are often classified by their specialized dentition. Almost all currently extant mammals are therians. The only exceptions are the platypus and the echidnas (spiny anteater), both of which are monotremes. Theria means beasts. Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms (as opposed to folk taxonomy). ... Phyla Subregnum Parazoa Porifera (sponges) Subregnum Agnotozoa Placozoa (trichoplax) Orthonectida (orthonectids) Rhombozoa (dicyemids) Subregnum Eumetazoa Radiata (unranked) (radial symmetry) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Bilateria (unranked) (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... Typical Classes Subphylum Urochordata - Tunicatas Ascidiacea Thaliacea Larvacea Subphylum Cephalochordata - Lancelets Subphylum Myxini - Hagfishes Subphylum Vertebrata - Vertebrates Petromyzontida - Lampreys Placodermi (extinct) Chondrichthyes - Cartilaginous fishes Acanthodii (extinct) Actinopterygii - Ray-finned fishes Actinistia - Coelacanths Dipnoi - Lungfishes Amphibia - Amphibians Reptilia - Reptiles Aves - Birds Mammalia - Mammals Chordates (phylum Chordata) include the vertebrates, together with... Orders Subclass Multituberculata (extinct) Plagiaulacida Cimolodonta Subclass Palaeoryctoides (extinct) Subclass Triconodonta (extinct) Subclass Eutheria (includes extinct ancestors)/Placentalia (excludes extinct ancestors) Afrosoricida Artiodactyla Carnivora Cetacea Chiroptera Cimolesta (extinct) Creodonta (extinct) Condylarthra (extinct) Dermoptera Desmostylia (extinct) Dinocerata (extinct) Embrithopoda (extinct) Hyracoidea Insectivora Lagomorpha Litopterna (extinct) Macroscelidea Mesonychia (extinct) Notoungulata (extinct) Perissodactyla... Metatheria is a grouping within the animal class Mammalia. ... Eutheria is a taxon (specifically, an infraclass) nearly synonymous with Placentalia, containing the placental mammals and the nearest ancestors of placental mammals (which are known only from the fossil record). ... Therianthropy is a generic term for any transformation of a human into another animal form, or for a being which displays both human and animal characteristics, either as a part of mythology or as a spiritual concept. ... IPA may refer to: The International Phonetic Alphabet or India Pale Ale ... Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms (as opposed to folk taxonomy). ... Orders Subclass Multituberculata (extinct) Plagiaulacida Cimolodonta Subclass Palaeoryctoides (extinct) Subclass Triconodonta (extinct) Subclass Eutheria (includes extinct ancestors)/Placentalia (excludes extinct ancestors) Afrosoricida Artiodactyla Carnivora Cetacea Chiroptera Cimolesta (extinct) Creodonta (extinct) Condylarthra (extinct) Dermoptera Desmostylia (extinct) Dinocerata (extinct) Embrithopoda (extinct) Hyracoidea Insectivora Lagomorpha Litopterna (extinct) Macroscelidea Mesonychia (extinct) Notoungulata (extinct) Perissodactyla... An average Whooping Crane egg is 102 mm long, and weighs 208 grams In some animals, an egg (Latin ovum) is the zygote, resulting from fertilization of the ovum. ... Orders Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia Xenarthra Dermoptera: Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Placentalia and Eutheria are terms used to describe major groupings within the animal class of Mammalia. ... Orders Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Marsupials are mammals in which the female typically has a pouch (called the marsupium, from which the name Marsupial derives) in which it rears its young through early infancy. ... In its most general form, a nipple is an appurtenance from which a fluid emanates, in this instance breast milk, to nurture a mothers young. ... Grays Fig. ... Dentition is the development of teeth and their arrangement in the mouth. ... Binomial name Ornithorhynchus anatinus (Shaw, 1799) The Platypus (Ornithorhynchus anatinus) is a small, half-aquatic mammal endemic to the eastern part of Australia, and one of the three extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young (the other two are echidnas). ... Species Genus Tachyglossus    T. aculeatus Genus Zaglossus    Z. attenboroughi    Z. bruijnii    Z. bartoni    Z. hacketti(extinct)    Z. robustus(extinct) Echidnas, also referred to by the name spiny anteaters, are the only surviving monotremes apart from the Platypus. ... Families Kollikodontidae(extinct) Ornithorhynchidae- Platypus Tachyglossidae- Echidnas Steropodontidae(extinct) Monotremes (monos, single + trema, hole; refers to the cloaca) are mammals that lay eggs, instead of giving birth to live young like marsupials (Metatheria) and placental mammals (Eutheria). ...