Theria

(redirected from therians)

Theria

One of the four subclasses of the class Mammalia, including all living mammals except the monotremes. The Theria were by far the most successful of the several mammalian stocks that arose from the mammallike reptiles in the Triassic. The subclass is divided into three infraclasses: Pantotheria (no living survivors), Metatheria (marsupials), and Eutheria (placentals). Therian mammals are characterized by the distinctive structural history of the molar teeth. The fossil record shows that all the extremely varied therian molar types were derived from a common tribosphenic type in which three main cusps, arranged in a triangle on the upper molar, are opposed to a reversed triangle and basinlike heel on the lower molar. See Mammalia

Theria

[′ther·ē·ə]
(vertebrate zoology)
A subclass of the class Mammalia including all living mammals except the monotremes.
References in periodicals archive ?
Charlie Cochet's Darkest Hour Before Dawn is the ninth installment in the THIRDS series, a paranormal gay romance saga about a militarized law enforcement team of Therians, humans that shape-shift into animals.
Dryolestoids are most closely related to a modern group of mammals called therians, which includes marsupials such as opossums and placental mammals such as people.
Typical n ode-based definitions, then, might read as follows: "Lepidosauria is the most recent common ancestor of Sphenodon and squamates and all of its descendants" or "Mammalia is the most recent common ancestor of montremes and therians and all of their descendants.
If these hypotheses are general for therians, it follows that in metatherians the extremely short gestation period, the need to achieve minimal functionality of somatic systems, the necessity for sufficient allocation to these systems for morphogenesis, and the rate-limiting nature of neurogenesis are incompatible.
182204, en: Mammal Phylogeny: Mesozoic differentiation, multituberculates, monotremes, early therians and marsupials (FS Szalay, MJ Novacek y MC McKenna, eds.
Therians comprise both the marsupials, such as the kangaroo, and the placental mammals, to which humans and most other living mammals belong.
Gray, 1907) that "in living therians, only the marsupial mole, the hedgehog, and the sea-cow posses a cochlea with as few as one and a half turns.
The faunule is composed exclusively of therian forms, and more specifically of zhelestid eutherians.
Petrosals of Late Cretaceous Marsupials from North America, and a Cladistic Analysis of the Petrosal in Therian Mammals.
The two most obvious features present in therian mammals but not shared by birds are a claustrum and the neocortical cytoarchitecture, including neurons with polarized dendrites, cortical columns, a great variety of cell types, and a highly stratified organization of afferent innervation.
An ontogenetic assessment of dental homologies in therian mammals.