prototherianadj.n.
/ˌprəʊtə(ʊ)ˈθɪərɪən/, U.S. /ˌproʊdəˈθɪriən/ Zoology and Palaeontology.
A. adj.
Of or relating to the subclass Prototheria of primitive mammals. Cf. Prototheria n.
ΘΚΠ
the world > animals > mammals > group Implacenta > [adjective] > relating to Prototheria or Monotremata
monotremous1826
monotrematous1832
monotremate1846
monotreme1865
monotremal1866
ornithodelphous1873
prototherian1880
1880 T. H. Huxley in Nature 6 Jan. 229/1 There is no known Monotreme which is not vastly more different from the Prototherian type.
1918 F. Wood-Jones Probl. Man's Ancestry 33 Such a lowly animal as the prototherian Duck-billed Platypus.
1974 D. Webster & M. Webster Compar. Vertebr. Morphol. v. 102 In prototherian and metatherian (but not eutherian) mammals there is a fourth skeletal element on each side [of the pelvic girdle], called the marsupial or prepubic bone.
1994 BioScience 44 21/1 The PGK-B isozyme is found in essentially all eutherian and metatherian (marsupial) mammalian species, but not in prototherian (monotreme) mammals.
B. n.
A primitive mammal of the subclass Prototheria; esp. a monotreme.
ΚΠ
1890 Cent. Dict. Prototherian,..a member of the Prototheria, hypothetical or actual.
1894–5 R. Lydekker Royal Nat. Hist. III. 283 Mammals are divided into three primary groups or subclasses, viz.: 1. Eutherians, or Placentals... 2. Metatherians, or Implacentals... 3. Prototherians, represented only by the Egg-laying Mammals.
1937 Q. Rev. Biol. 12 440/1 The step from living reptiles to therian mammals is a great one; and in most respects the latter differ almost as widely from prototherians.
2000 C. Tudge Variety of Life ii. xviii. 437 ‘Prototheria’ clearly is not a tidy clade—although ‘prototherian’ with a small ‘p’ can be used colloquially to mean ‘a (loosely defined) mammal that is not a therian’.
This entry has been updated (OED Third Edition, September 2007; most recently modified version published online March 2022).
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adj.n.1880