pseudoextinctionn.

Brit.

/ˌs(j)uːdəʊᵻkˈstɪŋ(k)ʃn/,

/ˌs(j)uːdəʊɛkˈstɪŋ(k)ʃn/, U.S.

/ˈˌsudoʊɪkˈstɪŋ(k)ʃ(ə)n/,

/ˈˌsudoʊɛkˈstɪŋ(k)ʃ(ə)n/

Origin: Formed within English, by compounding. Etymons: pseudo- comb. form, extinction n.

Etymology: < pseudo- comb. form + extinction n.

1. Physics. In a spectrographic trace, as of X-ray diffraction or atomic absorption: a barely visible or absent peak that would be expected to be strong from other considerations (cf. extinction n. 1c). Frequently attributive. pseudoextinction rule a method for calculating such peaks using mathematical modelling; usually in plural.

ΚΠ

1948 Analytica Chimica Acta 2 738 If only one cell-thickness is used in calibration and analysis, equation (2) can be simplified by introducing the ‘pseudo-extinction’ coefficient.

1956 Acta Crystallographica 9 1016/1 This pseudo-extinction can be accounted for by placing the iodine at z ≈ ½.

1964 Nature 8 Feb. 600/1 All diffraction data were consistent with a body-centred orthorhombic cell... Not only was the size of the cell extraordinary, but also the set of pseudo-extinction rules was most unusual.

2004 Materials Sci. & Engin. A. 373 94/2 Such atomic arrangement gives rise to pseudo-extinction, i.e., a strong reduction of the intensities of diffraction lines having h + k + l = 2n + 1.

2. Chiefly Palaeontology. The apparent extinction of a group of organisms whose descendants survive, but in a form modified by evolution (and hence are classified as a distinct group).

ΚΠ

1969 S. D. Webb in Evolution 23 692/1 A ‘taxonomic extinction’ results from arbitrary (but nonetheless necessary) change of generic names from an ancestral to a descendant stage within a continuous lineage. Such pseudoextinction will not be mistaken for the real termination of one lineage and the appearance of another, if the phylogenetic relationships are understood.

1975 Paleobiology 1 83/2 His analysis ignored pseudoextinction: the termination of a group not by extinction in the literal sense but by transformation (phyletically) into another group.

2002 S. J. Gould Struct. Evolutionary Theory viii. 606 Nearly all species terminate by true extinction and not by transformational passage into a descendant..(a phenomenon called ‘pseudoextinction’ by paleontologists).

Derivatives

ˌpseudoexˈtinct adj.

ΚΠ

1985 Proc. Amer. Philos. Soc. 129 413/1 An example at the specific level is the taxonomic sequence of Homo erectus, which according to the current consensus evolved into Homo sapiens. By this view, Homo erectus is pseudoextinct.

2000 Paleobiology 26 Suppl. 351/2 One can infer phylogeny from stratigraphy if all ancestral morphologies become pseudoextinct at speciation.

This is a new entry (OED Third Edition, September 2007; most recently modified version published online March 2022).

单词	pseudoextinction
释义	pseudoextinctionn. Brit. /ˌs(j)uːdəʊᵻkˈstɪŋ(k)ʃn/, /ˌs(j)uːdəʊɛkˈstɪŋ(k)ʃn/, U.S. /ˈˌsudoʊɪkˈstɪŋ(k)ʃ(ə)n/, /ˈˌsudoʊɛkˈstɪŋ(k)ʃ(ə)n/ Origin: Formed within English, by compounding. Etymons: pseudo- comb. form, extinction n. Etymology: < pseudo- comb. form + extinction n. 1. Physics. In a spectrographic trace, as of X-ray diffraction or atomic absorption: a barely visible or absent peak that would be expected to be strong from other considerations (cf. extinction n. 1c). Frequently attributive. pseudoextinction rule a method for calculating such peaks using mathematical modelling; usually in plural. ΚΠ 1948 Analytica Chimica Acta 2 738 If only one cell-thickness is used in calibration and analysis, equation (2) can be simplified by introducing the ‘pseudo-extinction’ coefficient. 1956 Acta Crystallographica 9 1016/1 This pseudo-extinction can be accounted for by placing the iodine at z ≈ ½. 1964 Nature 8 Feb. 600/1 All diffraction data were consistent with a body-centred orthorhombic cell... Not only was the size of the cell extraordinary, but also the set of pseudo-extinction rules was most unusual. 2004 Materials Sci. & Engin. A. 373 94/2 Such atomic arrangement gives rise to pseudo-extinction, i.e., a strong reduction of the intensities of diffraction lines having h + k + l = 2n + 1. 2. Chiefly Palaeontology. The apparent extinction of a group of organisms whose descendants survive, but in a form modified by evolution (and hence are classified as a distinct group). ΚΠ 1969 S. D. Webb in Evolution 23 692/1 A ‘taxonomic extinction’ results from arbitrary (but nonetheless necessary) change of generic names from an ancestral to a descendant stage within a continuous lineage. Such pseudoextinction will not be mistaken for the real termination of one lineage and the appearance of another, if the phylogenetic relationships are understood. 1975 Paleobiology 1 83/2 His analysis ignored pseudoextinction: the termination of a group not by extinction in the literal sense but by transformation (phyletically) into another group. 2002 S. J. Gould Struct. Evolutionary Theory viii. 606 Nearly all species terminate by true extinction and not by transformational passage into a descendant..(a phenomenon called ‘pseudoextinction’ by paleontologists). Derivatives ˌpseudoexˈtinct adj. ΚΠ 1985 Proc. Amer. Philos. Soc. 129 413/1 An example at the specific level is the taxonomic sequence of Homo erectus, which according to the current consensus evolved into Homo sapiens. By this view, Homo erectus is pseudoextinct. 2000 Paleobiology 26 Suppl. 351/2 One can infer phylogeny from stratigraphy if all ancestral morphologies become pseudoextinct at speciation. This is a new entry (OED Third Edition, September 2007; most recently modified version published online March 2022). < n.1948
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