Premium
Morphology and evolution of the dermal skeleton in lungfishes
Author(s) -
Meinke Deborah K.
Publication year - 1986
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1051900410
Subject(s) - skeleton (computer programming) , biology , appendicular skeleton , anatomy , axial skeleton , skeletal structures , devonian , morphology (biology) , evolutionary biology , paleontology
The dermal skeleton of lungfishes is primitively composed of thick cosmine‐covered bones and scales. Many Devonian lungfishes exhibit cosmine, while others have denticles of dentine and enameloid that may be arranged in several superposed layers; still others show denticles early in ontogeny superseded by cosmine later. Cosmine is a set of hard and soft tissues that includes bone, dentine, and enameloid, and a vascular and sensory porecanal network. It is the latter that uniquely distinguishes cosmine from other forms of the dermal skeleton and its presence determines the arrangement of the skeletal tissues. I have proposed that the appearance of denticles or cosmine is dependent on the stage of development of the pore‐canal system, which may be fully developed as a network or arrested at the free neuromast stage. Other evolutionary trends in the dipnoan dermal skeleton have resulted from repression of the tissue interactions that produce the skeletal tissues.