A review of the evolution of potamotrygonid freshwater stingrays (Chondrichthyes, Myliobatiformes).

Autor(en)

Rica Stepanek, Jürgen Kriwet

Abstrakt

Myliobatiformes form a monophyletic group characterized by one to several serrated tail spines. The phylogenetic relationships among the major lineages of myliobatiforms are still poorly resolved. The evolutionary history of South American freshwater Potamotrygonidae remains ambiguous. This is mainly because of the lack of fossils and because their sister group remains unsettled, with both Urobatis and Himantura being candidates. Potamotrygonidae includes four living genera, Heliotrygon, Paratrygon, Plesiotrygon, and Potamotrygon. The fossil record of freshwater stingrays is very patchy and includes rare isolated bucklers, tubercles, spines, and oral teeth occurring in the Middle Miocene of central Colombia, the Late Miocene of Brazil and the Late Miocene of Argentina. These very patchy occurrences may indicate a time of origination in the early Neogene, probably related to extrinsic factors such as plate tectonics.

Three different scenarios are conceivable: (1) change from a marine to euryhaline lifestyle in the ancestor of the clade including Himantura + Potamotrygon and then a second change to a freshwater lifestyle in the Potamotrygon lineage; (2) the ancestor of the Himantura + Potamotrygon clade also was marine and each lineage made an independent change to a euryhaline (Himantura) or a freshwater (Potamotrygon) lifestyle; and (3) direct change from a marine to freshwater lifestyle in the ancestor of the Himantura + Potamotrygon clade, and then a second change to euryhaline lifestyle in the Himantura lineage. If Paratrygon represents the most basal potamotrygonid, it might have been the first true freshwater member of this group and the onset of their radiation.

Organisation(en)

Institut für Paläontologie

Publikationsdatum

2011

ÖFOS 2012

105118 Paläontologie

Sustainable Development Goals

SDG 14 – Leben unter Wasser

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/f7a9f3cf-08e1-4932-a666-6e12e6c449ed