- BIG TEETH, STRONG FINS
Subclass Crossopterygii, "lobe finned" Fish
The lobe-finned fishes, Crossopterygii, a major group
of large predators in the Devonian are today represented by a
sole surviving species, the coelacanth Latimeria chalumnae. Several
types of crossopterygians arose by the Middle Devonian, including
osteolepiforms, the group which gave rise to four-legged animals.
Although crossopterygians such as porolepiforms and onychodontiforms
achieved a peak of diversity during the Devonian and then mysteriously
disappeared, others reached their acme in the Carboniferous (coelacanths
and rhizodontiforms). Coelacanths, the only crossopterygians
to survive the Palaeozoic, quickly reached their modern form
by Mesozoic Era and have remained relatively unchanged. (See
Chapter 9.)
Summary by Dr. Irwin Haydock of the book entitled The Rise
of Fishes, 500 million years of evolution, by John A. Long, Johns
Hopkins University Press, 1995. (See Chapter 9)
If you would like to learn more about the evolution of fishes,
we recommend Long's excellent book. It's loaded with information,
well written and easy to understand.
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