Definition of therian in English:

therian

noun

Zoology
  • A mammal of the major group Theria, which comprises the marsupials and placentals.

    • ‘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.’
    • ‘The reproductive system of the therians (marsupial and placental mammals) is a complex variation on the egg-layer's basic tubular structure.’
    • ‘The evolutionary tree relating the mammalian species that share the amino-acid replacements dates back to the ancestral therian, 180 million years ago.’
    • ‘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.’
    • ‘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.’

adjective

Zoology
  • Relating to or denoting therians.

    • ‘The physiological site of the defect in these mice, the chorionic placenta, is found only in therian mammals.’
    • ‘As one might guess, the post-cranial skeleton is a mosaic of basal mammaliform and therian characters.’
    • ‘Thus, relative to the primitive therian condition, marsupials have a distinctive, derived pattern of reduced dental replacement.’
    • ‘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.’
    • ‘Unfortunately, molar nomenclature was developed for therian mammals, and some of the terminology turns out not to work very well at this fundamental level.’

Pronunciation

therian

/ˈTHirēən/