Placoderm

A placoderm is an extinct jawed vertebrate with bony plates armoring its head and trunk. Placoderms were especially diverse during the Devonian Period.

Gnathostomata: Gnathostomata is the clade of vertebrates with jaws, including placoderms, cartilaginous fishes, and bony vertebrates. Placoderms belong to this broad group of jawed vertebrates.
Arthrodira: Arthrodira is the largest placoderm order, known for hinged armor between the head and trunk shields. Its armor articulation illustrates a major placoderm body plan.
Paleozoic: The Paleozoic Era lasted from about 539 to 252 million years ago, before the Mesozoic. Placoderms arose and diversified during this era.
Bothriolepis: Bothriolepis was a widespread Devonian placoderm genus with extensive armor and distinctive pectoral appendages. Its fossils document a common, widespread placoderm body plan.
Vertebrate jaw evolution: Vertebrate jaw evolution is the history of how jaws arose and diversified among vertebrates. Placoderm jaws preserve early evidence for the diversification of jaw structures.
Dermal bone: Dermal bone forms directly within connective tissue rather than from a cartilage template. Placoderm armor consisted of dermal bone plates.
Dunkleosteus: Dunkleosteus was a large Late Devonian arthrodire with bony plates forming powerful jaw edges. Its feeding anatomy shows how some placoderms seized and processed prey.
Devonian: The Devonian Period lasted from about 419 to 359 million years ago and is known for major fish diversification. Placoderms reached their greatest diversity during the Devonian.
Materpiscis: Materpiscis is a Devonian placoderm genus known from a fossil preserving an embryo and umbilical connection. Its fossil provides rare evidence of reproductive biology in placoderms.
Evolution of the vertebrate skeleton: The evolution of the vertebrate skeleton traces changes in cartilage, bone, and skeletal organization. Placoderms clarify how mineralized skeletons developed among jawed vertebrates.

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