Cosmine
Cosmine is a spongy, bony material that makes up the
Description
As traditionally described,[2] cosmine consists of a layer of dentine covered by a continuous sheet of enamel. Pulp cavities, which secrete dentine tubules, are surrounded by a complex polygonal network of 'pore cavities' which pierce the overlying enamel layer, giving cosmine its characteristic dotted appearance.[3] The pulp cavities and pore chambers are connected by a complex, reticulated pore canal network which continues into a layer of vascular bone beneath the dentine. The exact configuration of the pore canal network and shape of the pore chambers differs between various taxa, although the general organization into a single layer of enamel over dentine with pore canals with vascular bone underneath remains consistent, at least within the Sarcopterygii.[3]
History
Cosmine was first described in the
Phylogenetics
New fossils from China have altered current understanding of early fish evolution. Many of these fossils have been identified on the basis of histological characteristics, such as
See also
References
- ISSN 1631-0683.
- JSTOR 108487.
- ^ a b c (geologist.), Walter Gross (1956). Über Crossopterygier und Dipnoer aus dem baltischen Oberdevon im Zusammenhang einer vergleichenden Untersuchung des Porenkanalsystems paläozoischer Agnathen und Fische (in German). Almqvist & Wiksell.
- ^ Donoghue, Philip C.J. "Evolution of Development of the Vertebrate Dermal and Oral Skeletons: Unraveling Concepts, Regulatory Theories, and Homologies" (PDF).
- ISSN 1469-7998.
- ^ ISSN 1502-3931.
- .
- S2CID 1840338.
- PMID 27212403.
- S2CID 3497774.
Further reading
- Ørvig, TOR (1969). "Cosmine and Cosmine Growth". Lethaia. 2 (3): 241–260. .
- Meinke, Deborah K. (1984). "A review of cosmine: Its structure, development, and relationship to other forms of the dermal skeleton in osteichthyans". Journal of Vertebrate Paleontology. 4 (3): 457–470. .
- On the biology of cosmine