Cosmoid scale

Coelacids with distinct cosmoid scales

Cosmoid scales or cosmoid scales are a type of scale that can recently only be found in the coelacanth , but fossilized cover the skin of all meat finfish. The cosmoid scale developed from the same precursor as the ganoid scale .

Cosmoid scales consist of a lamellar bone ( isopedin ) located deep in the epidermis , on which cancellous bone rests and merges into the flaky cosmin . This consists of dentin on which enamel is deposited. The dentine has a branched system of canals in which the extensions of the scale-forming cells, the odontoblasts , lie. They also contain bottle-shaped depressions in which blood vessels lie.

Scales of today's Australian lungfish

The recent lung fish , whose fossil representatives also had cosmoid scales, have a thin epidermal bone layer on mineralized connective tissue without pore channels and dentin in the skin. The scales are correspondingly very thin structures.

See also

• Elasmoid scale
• Placoid scale

swell

literature

• Harald Schliemann: integument and appendage organs. In: Wilfried Westheide , Reinhard Rieger (conception): Special Zoology, Part 2: Vertebrate or skull animals . Spektrum Akademischer Verlag, Munich 2004, ISBN 3-8274-0307-3 , pp. 547-549.