- TRUE BONY FISHES AND THEIR ORIGINS
- Class Osteichthyes
Osteichthyans (meaning “bony fishes”) are the largest,
most diverse vertebrate group, represented chiefly by today’s
ray-finned fishes (Subclass Actinopterygii). However, their origins
date back to Late Silurian, some 410 mya, when they were only
a minor component of the ancient fish faunas. By the start of
the Devonian all major groups of bony fishes had appeared, and
before the end of the Period the first land animals had evolved
from within the lobe-finned bony fishes (Sarcopterygii). Bony
fishes include the ray-fins (Actinopterygii), lungfishes (Dipnoi)
and predatory lobe-fins (Crossopterygii).
Buried within the early evolution of osteichthyan fishes
lies the key to the most complex evolutionary transition in vertebrate
history: how a water-breathing fish became a land-living amphibian.
One secret of the “bony fishes” success lies in their
swim-bladder, an internal organ of buoyancy, which was to become
modified into the lungs of land animals.
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 6)
If you would like to learn more about the evolution of fishes,
we highly recommend Long's book. It's excellent !! It's loaded
information that is well written and easy to understand.
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