SYSTEMATIC POSITION OF THE CONTINENTAL LATE JURASSIC TELEOST LUISIELLA FERUGLIOI FROM PATAGONIA (ARGENTINA) AND THE OCCURRENCE OF A NEW GONDWANAN CLADE OF BASAL TELEOSTS.

E. SFERCO; A. LÓPEZ.ARBARELLO; A. M. BÁEZ

Berlín

Congreso; 74th Annual Meeting SVP; 2014

Society of Vertebrate Paleontology

Luisiella feruglioi (Bordas) is the main component of the Almada Fish Fauna of the continental Cañadon Calcareo Formation in Chubut, Argentina, representing one of the few Jurassic records of freshwater teleosts and the oldest known from South America to date. To evaluate its systematic position, a data matrix of 61 taxa (including 46 extinct and 15 living species) and 180 morphological characters from previous cladistic analyses as well as additional ones was built. After a thorough revision, most original characters were re-codified and special care was taken to avoid character definitions that imply the use of unspecified "absence" states. Ingroup taxa included the Australian freshwater teleosts Cavenderichthys talbragarensis (Woodward) from the Upper Jurassic Talbragar Beds and Leptolepis koonwarri Waldman, from the Lower Cretaceous Koonwarra Beds. Also, several taxa previously regarded as stem-group Teleostei and now considered as basal teleosts (e.g., Siemensichthys, Eurycormus) were included in the dataset. The parsimony analysis resulted in ten most parsimonious trees (MPT´s) of 817 steps each, all of them supporting the monophyly of Teleostei sensu stricto. In all MPT´s, L. feruglioi is recovered as a basal teleost immediately above the level of Leptolepis coryphaenoides (Bronn) and the sister taxon of C. talbragarensis, both taxa in turn forming a monophyletic group with Leptolepis koonwarri. The grouping of these three taxa represents a distinct Gondwanan clade of freshwater basal teleosts that evolved independently from marine basal teleosts of Europe and Chile. These results point to an earlier colonization of freshwater environments by teleost fishes than previously thought.