Prototherian.
/ˌprəʊtə(ʊ)ˈθɪərɪə/, U.S. /ˌproʊdəˈθɪriə/ Zoology and Palaeontology.
With singular agreement: a subclass of mammals comprising the monotremes and their extinct relatives. With plural agreement (also prototheria): mammals of this subclass collectively; prototherians.The extent of the taxon Prototheria, and the characters that distinguish it, are not yet resolved.
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the world > animals > mammals > group Implacenta > [noun] > group Prototheria or Monotremata
Monotremata1832
Ornithodelphia1864
Prototheria1880
1880 T. H. Huxley in Proc. Zool. Soc. 653 It will be convenient to have a distinct name, Prototheria, for the group which includes these, at present, hypothetical embodiments of that lowest stage of the mammalian type, of which the existing Monotremes are the only known representatives.
1911 E. M. Clowes On Wallaby xi. 288 The egg-laying mammals, or prototheria.
1986 A. S. Romer & T. S. Parsons Vertebr. Body (ed. 6) iii. 84 We here adopt the idea that all mammals may be divided into two separate lines...One line, the subclass Prototheria (a word of warning: this term is frequently used in a much more restrictive sense), consists of forms in which much of the lateral wall of the braincase is formed by the periotic.
1991 R. M. Nowak Walker's Mammals of World (ed. 5) I. 1/1 The Prototheria comprise the extinct infraclass Eotheria and the infraclass Ornithodelphia with the orders Monotremata and Multituberculata.
This entry has been updated (OED Third Edition, September 2007; most recently modified version published online March 2022).
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