A mammal of the major group Theria, which comprises the marsupials and placentals.
‘The reproductive system of the therians (marsupial and placental mammals) is a complex variation on the egg-layer's basic tubular structure.’
‘First, we point out that the loss of tooth replacement in marsupials is neither unusual among therian mammals nor highly correlated with the extended period of nipple attachment in any obvious manner.’
‘Fossils of therian mammals, which include the marsupials as well as the eutherians, may be recognized and distinguished by the number, morphology, and replacement pattern of their teeth.’
‘In this way the ancestor of therian mammals came to possess a single generation of replacement teeth, which erupt when the jaw reaches a size large enough to accommodate them.’
‘The evolutionary tree relating the mammalian species that share the amino-acid replacements dates back to the ancestral therian, 180 million years ago.’
adjective
Zoology
Relating to or denoting therians.
‘Thus, relative to the primitive therian condition, marsupials have a distinctive, derived pattern of reduced dental replacement.’
‘The physiological site of the defect in these mice, the chorionic placenta, is found only in therian mammals.’
‘Unfortunately, molar nomenclature was developed for therian mammals, and some of the terminology turns out not to work very well at this fundamental level.’
‘As one might guess, the post-cranial skeleton is a mosaic of basal mammaliform and therian characters.’
‘In this way the ancestor of therian mammals came to possess a single generation of replacement teeth, which erupt when the jaw reaches a size large enough to accommodate them.’
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