placoderm
noun
plac·o·derm
ˈpla-kə-ˌdərm 
: any of a class (Placodermi) of extinct chiefly Devonian fishes with an armor of bony plates and primitive jaw structures
Examples of placoderm in a Sentence
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As a placoderm, Alienacanthus belonged to the earliest groups of vertebrates to develop complex jaws.
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Jack Tamisiea, New York Times, 30 Jan. 2024
Dunkleosteus, a genus from a class of armored fish called the placoderms, reached greater dimensions and could have easily preyed on early chondrichthyans.
—Joshua Rapp Learn, Discover Magazine, 1 Apr. 2023
Enlarge / Reconstruction of a Devonian arthrodire placoderm.
—Jennifer Ouellette, Ars Technica, 21 Sep. 2022
Trinajstic and her team had previously discovered mineralized muscle tissue in these same placoderm fossils.
—Stephanie Pappas, Scientific American, 15 Sep. 2022
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Jack Tamisiea, New York Times, 30 Jan. 2024
Dunkleosteus, a genus from a class of armored fish called the placoderms, reached greater dimensions and could have easily preyed on early chondrichthyans.
—Joshua Rapp Learn, Discover Magazine, 1 Apr. 2023
Enlarge / Reconstruction of a Devonian arthrodire placoderm.
—Jennifer Ouellette, Ars Technica, 21 Sep. 2022
Trinajstic and her team had previously discovered mineralized muscle tissue in these same placoderm fossils.
—Stephanie Pappas, Scientific American, 15 Sep. 2022
Cite this Entry
“Placoderm.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/placoderm. Accessed 10 Sep. 2025.
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