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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.]


(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]


(ˈplæk əˌdɜrm)

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 ?
Copulation in antiarch placoderms and the origin of gnathostome internal fertilization.
The fossil was found in limestone at Lake Burrinjuck in southeastern Australia, close to the capital Canberra, and is from one of an extinct group of armored fish known as placoderms.
2003; Turner and Miller 2008) and placoderms (Young 1983), almost all from the breccia-mudstone at the eastern end of the 'Atholville Beds' in Campbellton.
The discovery of a 423-million-year-old armored fish from China suggests that the jaws of all modern bony fish and land vertebrates originated in a bizarre group of fish called placoderms, researchers report in the Oct.
Scientists were excited by its mix of traits from placoderms - an extinct armoured fish - and bony fish, which gave rise to all modern fish that have jaws and skeletons made of bone.
Among other things it contains placoderms, an extinct group that includes some of the earliest jawed fish.
Several marine fossils not found in underlying formations suddenly appear here, including those of gastropods; crinoids; rare corals; small conodonts (eel-like creatures); and armored, plate-mouthed fish known as placoderms.
The volume also highlights the Devonian period with three articles on placoderms, the Gogo fish fossils, and the origin of whales.
Dunkleosteus was one of many species of placoderms, a diverse group of armoured fishes that dominated aquatic ecosystems during the Devonian period, from 415 million to 360 million years ago.
The sculpture of stellate tubercles and open lateral line canals of Lophosteus platelets have superficial similarities with some placoderms, for example, with radotinids.
The first data about placoderms from Plucki were presented by Ivanov & Ginter (1997) who initially described a partly preserved skull-roof of an eastmanosteid arthrodire.