March 8, 2017
An ancient fish species with
unusual scales and teeth from the Kuanti Formation in southern China may have
evolved prior to the "Age of Fish", according to a study published
March 8, 2017 in the open-access journal PLOS ONE by Brian Choo from Flinders
University, Australia, and colleagues at the Institute of Vertebrate
Paleontology and Paleoanthropology, China.
The Devonian Period (419.2 -
358.9 million years ago) is popularly called the "Age of Fishes"
because of the apparent increase in the abundance and variety of jawed fishes
when compared with the preceding Silurian Period (443.7 - 419.2 million years
ago). Until recently, the Silurian fossil record of jawed vertebrates has been
based on highly fragmentary remains, limiting our understanding of their early
evolution. Recent discoveries from the Kuanti Formation of Yunnan, southwestern
China, have dramatically enhanced our knowledge, with several superbly
preserved fish species described in recent years. The fish-bearing sediments of
the Kuanti Formation have been dated to the latter part of the Silurian, about
423 million years ago.
Now, Choo and colleagues have
described a new genus and species of Kuanti fish, Sparalepis tingi, which
represents only the second Silurian bony fish
based on more than isolated fragments. This new form, along with its
contemporary Guiyu and the slightly more recent Psarolepis, possesses
spine-bearing pectoral and pelvic girdles, features once thought to be
restricted to the armored placoderm fishes. Sparalepis and its kin may
represent an early radiation of stem-sarcopterygians, ancient cousins of modern
lungfish, coelacanths and tetrapods.
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