New aspidorhynchiform (Neopterygii, Teleosteomorpha) from the Late Jurassic of Neuquén Province, Southern Argentina

SOLEDAD GOUIRIC CAVALLI

Diamante, Entre Ríos

Jornada; XXIX Jornadas Argentinas de Paleontología de Vertebrados; 2015

Aspidorhynchiformes is a group of extinct neopterygians that have been traditionally considered typical marine forms having worldwide distribution except Asia. The group is considered monophyletic and to date consists of a single family with four nominal genera. The great part of the anatomical descriptions as well as almost the whole information about the group is based mainly on incomplete specimens. The general morphology of most of the species (including braincase, skull bones, caudal skeleton, paired and unpaired fins, and scales) is incompletely known. In Argentina they are poorly known being the best-preserved material recovered from marine Upper Jurassic (Tithonian) sediments of the Vaca Muerta Formation at Neuquén Province. Here, a new aspidorhynchiform is reported. Although the taxon is so far represented by a single specimen, preservation allows a detailed description. The new taxon is diagnosed by a unique combination of characters (e.g., large skull roof plate composes by the fusion of certain bones; L-shaped preopercle with a single main preopercular sensory canal; three predentary teeth rows; an accessory cusp in teeth of the median predentary teeth row, and a robust and deep body). The new endemic aspidorhynchiform increases the known diversity of the group, particularly in Gondwana. The morphological information provided here could be useful to further understanding of aspidorhynchiforms phylogeny and Neuquén Basin biodiversity.