The Ordovician enigma: fish, first appearances and phylogenetic controversies

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Abstract

The Ordovician history of fish is limited by a combination of biological, environmental and taphonomic constraints, but appears to contain significant milestones referencing to the first appearances of a number of major groups including putative jawed fish. In addition, the depositional settings from which fish are recovered are restricted to a narrow range of environments and, similarly, the stratigraphic coverage remains patchy despite increases in reporting over recent years. The Gondwanan and Laurentian record further diminishes with the onset of the end-Ordovician glaciation and concomitant extinction event; a pattern which continues into ‘Talimaa’s Gap’ at the base of the Silurian. Phylogenetically, many of the Ordovician taxa are problematic to place in the higher taxonomic groupings that dominate the Siluro-Devonian. With caution, a number of the scale-based taxa fall within the crown-gnathostomes reemphasizing the importance of the Great Ordovician Biodiversification Event in setting the scene for subsequent vertebrate evolutionary radiations and range expansions.

Details

Original languageEnglish
Title of host publicationEvolution and Development of Fishes
EditorsZerina Johanson, Martha Richter, Charles Underwood
Publication statusAccepted/In press - 12 Jun 2017