Athena Review Image Archive ™
Fish and Tetrapod evolution chart
Fish and Tetrapod evolution chart (after Romer 1966; Athena Review).
This
seriation chart shows the relative frequencies of various classes of fish,
together with tetrapods grouped as whole at right, from the Cambrian
period through the present. Major extinction events occurred for early
fishes during the Devonian period, and at the end of the Permian period at
about 252 mya. At that point, most lobe-fin fishes or
Sarcopterygians (who were the ancestors of tetrapods) became extinct.
Nearly all fish today, except for cartilaginous sharks and rays, are ray-finned or Actinopterygian.
References:
Romer, A.S. 1956, 1966. Vertebrate Paleontology. University of Chicago Press.
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