placodermn.adj.

Brit.

/ˈplakə(ʊ)dəːm/, U.S.

/ˈplækəˌdərm/

Origin: Formed within English, by compounding; modelled on a German lexical item. Etymons: placo- comb. form, -derm comb. form.

Etymology: < placo- comb. form + -derm comb. form, after German Placoderm ( C. H. Pander Über die Placodermen des devonischen Systems(1857)). Compare scientific Latin Placodermi , class name (F. M'Coy 1848, in Ann. & Mag. Nat. Hist. 2 6), and also scientific Latin Placodermata , class name (1859 or earlier: compare quot. 1859 at sense A.; Pander apparently only uses the German word).

Palaeontology.

A. n.

A member of the extinct class Placodermi of jawed fishes, known mainly from fossils of the Silurian and Devonian periods, having the head and pectoral region encased in broad, flat bony plates.

ΘΚΠ

the world > animals > fish > superclass Agnatha > [noun] > class Chondrichthyes > member of Placodermata

placoderm1859

1859 D. Page Handbk. Geol. Terms 294 Placodermata, Placoderms,..Dr. Pander's term for the bony-plated or bone-encased fishes of the Old Red Sandstone.

1886 A. Winchell Walks & Talks in Geol. Field 239 The placoderm was destined to disappear with the Devonian period.

1968 R. Zangerl tr. B. Peyer Compar. Odontol. 30 The placoderms are all more or less clearly gnathostomous.

1996 Q. Rev. Biol. 71 399/2 The range of anatomical diversity displayed by Devonian fishes..included the jawless ostracoderms, armor-plated placoderms, spiny acanthodians and primitive aquatic tetrapods.

B. adj.

Of or relating to the class Placodermi.

ΚΠ

1884 Amer. Naturalist 18 1140 Dr. J. S. Newberry not long ago descried the new placoderm genus Myzostoma, with two species, variabilis and terreli.

1890 Cent. Dict. Placoderm, having the skin covered with broad, flat plates, as a fish; belonging to the Placodermi.

1966 A. S. Romer Vertebr. Paleontol. (ed. 3) iii. 32/1 There has been discovered in the Mississippian a single fragmentary specimen of a fish, Cratoselache, which..has a few vestiges of placoderm armor.

1999 J. A. Long in R. Singer Encycl. Palaeontol. II. 919/1 Placoderm fossils are useful biostratigraphic markers because even partial plates are often identifiable down to the species level.

Derivatives

† placodermal adj. Obsolete rare

ΚΠ

1885 R. Etheridge Phillips's Man. Geol. (new ed.) II. i.6 Crossopterygian, Acanthodian, and Placodermal (Elasmobranch) forms were Carboniferous and Devonian.

This entry has been updated (OED Third Edition, June 2006; most recently modified version published online March 2022).

单词	placoderm
释义	placodermn.adj. Brit. /ˈplakə(ʊ)dəːm/, U.S. /ˈplækəˌdərm/ Origin: Formed within English, by compounding; modelled on a German lexical item. Etymons: placo- comb. form, -derm comb. form. Etymology: < placo- comb. form + -derm comb. form, after German Placoderm ( C. H. Pander Über die Placodermen des devonischen Systems(1857)). Compare scientific Latin Placodermi , class name (F. M'Coy 1848, in Ann. & Mag. Nat. Hist. 2 6), and also scientific Latin Placodermata , class name (1859 or earlier: compare quot. 1859 at sense A.; Pander apparently only uses the German word). Palaeontology. A. n. A member of the extinct class Placodermi of jawed fishes, known mainly from fossils of the Silurian and Devonian periods, having the head and pectoral region encased in broad, flat bony plates. ΘΚΠ the world > animals > fish > superclass Agnatha > [noun] > class Chondrichthyes > member of Placodermata placoderm1859 1859 D. Page Handbk. Geol. Terms 294 Placodermata, Placoderms,..Dr. Pander's term for the bony-plated or bone-encased fishes of the Old Red Sandstone. 1886 A. Winchell Walks & Talks in Geol. Field 239 The placoderm was destined to disappear with the Devonian period. 1968 R. Zangerl tr. B. Peyer Compar. Odontol. 30 The placoderms are all more or less clearly gnathostomous. 1996 Q. Rev. Biol. 71 399/2 The range of anatomical diversity displayed by Devonian fishes..included the jawless ostracoderms, armor-plated placoderms, spiny acanthodians and primitive aquatic tetrapods. B. adj. Of or relating to the class Placodermi. ΚΠ 1884 Amer. Naturalist 18 1140 Dr. J. S. Newberry not long ago descried the new placoderm genus Myzostoma, with two species, variabilis and terreli. 1890 Cent. Dict. Placoderm, having the skin covered with broad, flat plates, as a fish; belonging to the Placodermi. 1966 A. S. Romer Vertebr. Paleontol. (ed. 3) iii. 32/1 There has been discovered in the Mississippian a single fragmentary specimen of a fish, Cratoselache, which..has a few vestiges of placoderm armor. 1999 J. A. Long in R. Singer Encycl. Palaeontol. II. 919/1 Placoderm fossils are useful biostratigraphic markers because even partial plates are often identifiable down to the species level. Derivatives † placodermal adj. Obsolete rare ΚΠ 1885 R. Etheridge Phillips's Man. Geol. (new ed.) II. i.6 Crossopterygian, Acanthodian, and Placodermal (Elasmobranch) forms were Carboniferous and Devonian. This entry has been updated (OED Third Edition, June 2006; most recently modified version published online March 2022). < n.adj.1859
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