Upper Triassic semionotids from western Gondwana

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Semionotids are among the most important, though less understood basal neopterygian fishes. They represent one of the first and most important radiations of this group, which also includes the teleosts and thus most of the Recent bony fishes. Therefore, knowledge of basal neopterygian phylogenetic relationships and evolution is essential to understand teleost evolution and biodiversity. Since teleosts originated in the late Triassic, the early history of basal neopterygians like the semionotiformes is of special interest. The early fossil record of the semionotiforms is largely biased to the Northern Hemisphere and very little is known about the origin and first radiation of this group in Gondwana. The continental Upper Triassic Cacheuta Formation (Norian) in Argentina has yielded one of the very few records of the group in the Triassic of Gondwana and the only Triassic articulated semionotid remains in South America. This fish, Semionotus vallejensis, thus represents a unique opportunity to have an insight into the early history of semionotiforms in Western Gondwana. The aim of this project is to carry out a fieldwork campaign to collect more material of Semionotus vallejensis, so far represented by a single incompletely preserved specimen. With the new material, the taxon will be studied in detailed, including a taxonomic revision and analysis of its phylogenetic relationships.