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ON THE EVOLUTION OF BONY FISHES DURING THE TRIASSIC PERIOD
Author(s) -
BROUGH JAMES
Publication year - 1936
Publication title -
biological reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.993
H-Index - 165
eISSN - 1469-185X
pISSN - 1464-7931
DOI - 10.1111/j.1469-185x.1936.tb00912.x
Subject(s) - permian , carboniferous , paleontology , paleozoic , group (periodic table) , period (music) , early triassic , geology , chemistry , physics , organic chemistry , structural basin , acoustics
Summary The Palaeoniscidae was the dominant group of bony fishes during Carboniferous and Permian times. This large and varied group of fishes has usually been called the “family Palaeoniscidae”, but it appears to consist of several independent lines. The Holostei were evolved from the Palaeoniscidae before the beginning of the Triassic, Acentrophorns , the earliest member, appearing in the upper Permian. About the close of the Palaeozoic era the Palaeoniscidae gave rise to several independent families which become modified to a greater or less extent toward the holostean grade of structure. These groups are referred to as the sub‐holostean families. The parallel modifications they display include the reduction of the scaly lobe of the tail, reduction of the fin rays, loss of the cosmine layer of the scales, and the swinging forward of the suspensorium. The modifications proceeded much further in some groups than in others. It is shown that although these Triassic families did not give rise to the Holostei, they provide a perfect Sci of intermediate forms between the palaeoniscid and the holostean condition. One of the sub‐holostean families, the Catopteridae, is analysed and its evolving characters separated into those which are parallel (also undergone by other groups) and those which are characteristic of the family. Reasons are Sci out for supposing the Catopteridae to have been derived from the Dicellopygae group of the Palaeoniscidae.