单词 | placoderm |
释义 | placoderm[ plak-uh-durm ] / ˈplæk əˌdɜrm / nounany of various extinct jawed fishes of the class Placodermi, dominant in seas and rivers during the Devonian Period and characterized by bony armored plates on the head and upper trunk. Origin of placoderm1855–60; <New Latin Placodermi name of the class, plural of placodermus, equivalent to placo- (<Greek; see placoid, -o-) + -dermus-derm Words nearby placodermplacing, plack, plackart, placket, placode, placoderm, placoid, plafond, plagal, plagal cadence, plage Dictionary.com UnabridgedBased on the Random House Unabridged Dictionary, © Random House, Inc. 2020 Example sentences from the Web for placoderm
British Dictionary definitions for placodermplacoderm / (ˈplækəˌdɜːm) / nounany extinct bony-plated fishlike vertebrate of the class Placodermi, of Silurian to Permian times: thought to have been the earliest vertebrates with jaws Word Origin for placodermC19: from Greek plac-, plax a flat plate + -derm Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Scientific definitions for placodermplacoderm [ plăk′ə-dûrm′ ] Any of various extinct fishes of the class Placodermi of the Silurian and Devonian Periods, characterized by bony plates of armor covering the head and flanks. The bodies of placoderms were spindle-shaped or flattened, and their skeletons were usually partially bony and included a cranium. Placoderms were the first group of fish to evolve jaws, but are not closely related to the jawed fish of today. The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved. |
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