Definition of Placodermi
: a class of extinct fishes with an armor of large bony plates and primitive jaw structures that has been taken as equivalent to Antiarcha plus Arthrodira but is now usually extended to include also the Acanthodii, Cycliae, and minor groups — compare chondrichthyes
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Origin and Etymology of placodermi
New Latin, from plac- + Greek derma skin — more at derm-
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