Definition of Prototheria in English:

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Pronunciation: /ˌprōdəˈTHirēə/
A group of mammals that comprises the monotremes and their extinct relatives. Compare with Theria.
  • Subclass Prototheria, class Mammalia.
Example sentences
  • They are often placed in a separate subclass from other mammals, Prototheria.
  • Triconodonta were viewed as broadly ancestral to the extinct Docodonta and to living monotremes, collectively grouped (often with Multituberculata) as Prototheria.
  • As noted, recognition of skull resemblances to monotremes and triconodonts led to later referral to ‘Prototheria,’ within a monophyletic Mammalia.


Modern Latin (plural), from proto- 'first, original' + Greek thēr 'wild beast'.

For editors and proofreaders

Syllabification: Pro·to·the·ri·a

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