placoderm


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pla·co·derm

 (plăk′ə-dûrm′)
n.
Any of various extinct jawed fishes of the group Placodermi of the Silurian and Devonian Periods, having bony plates of armor covering the head and thorax. Placoderms were among the first jawed vertebrates.

[New Latin Placodermī, class name : Greek plax, plak-, flat stone, plate; see plāk- in Indo-European roots + -derm.]

placoderm

(ˈplækəˌdɜːm)
n
(Palaeontology) any extinct bony-plated fishlike vertebrate of the class Placodermi, of Silurian to Permian times: thought to have been the earliest vertebrates with jaws
[C19: from Greek plac-, plax a flat plate + -derm]

plac•o•derm

(ˈplæk əˌdɜrm)

n.
any of various extinct jawed fishes of the class Placodermi, chiefly of the Devonian Period: many were armored in bony plates.
[1855–60; < New Latin Placodermi name of the class, pl. of placodermus=placo- (< Greek; see placoid, -o-) + -dermus -derm]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.placoderm - fish-like vertebrate with bony plates on head and upper body; dominant in seas and rivers during the Devonian; considered the earliest vertebrate with jaws
aquatic vertebrate - animal living wholly or chiefly in or on water
class Placodermi, Placodermi - extinct group of bony-plated fishes with primitive jaws
References in periodicals archive ?
They were interpreted as the result of placoderm fish dragging or pushing off the sediment.
Along with a different placoderm fossil found in 2013, the new find, named Qilinyu rostrata, is helping rewrite the story of early vertebrate evolution, says paleontologist John Maisey of the American Museum of Natural History in New York City.
Matt Friedman, a paleobiologist at Oxford University, said: "If you look at just the top of the skull and the body, it looks like a placoderm.
The scientists studied the skull of Romundina, an early armoured fish with jaws, or placoderm, from arctic Canada.
These morphological transitions, they note, are concomitant with radiations of shell-crushing placoderm and chondrichthyan fish.
Psammosteid heterostracans (Pteraspidomorpha) predominate in number among species-level taxa, but the specimens of antiarch placoderm remains are most numerous.
Qilinyu and Entelognathus - another placoderm from the same period found in 2013 in the same region - exhibit the first instance of distinct maxillary, premaxillary and dentary bones.
Lead author Min Zhu, of the Chinese Academy of Sciences' Institute of Vertebrate Paleontology and Paleoanthropology, added that entelognathus was "a placoderm, an extinct grade of primitive armored fishes.
To find out, he says, the researchers first need to confirm that the muscles were present in all types of placoderms, not unique to the one placoderm group studied.
It resembles a tiny tooth and I'm wondering if it might be from a placoderm fish.