Late Mesozoic antarctic fishes: a review and future perspectives

GOURIC-CAVALLI SOLEDAD; MOLY, J.J.; TALEVI, M.; ARI IGLESIAS; SANTILLANA, S.; MARCELO REGUERO; ACOSTA BURLLAILE; JOSE O´GORMAN; VIEYTES, C.

Mahasarakham

Congreso; 7th International Meeting on Mesozoic Fishes; 2017

Palaeontological Research and Education Centre

The LarsenBasin includes all the upper Mesozoic?lower Cenozoic sedimentary rocks on thecontinental shelf east of the Antarctic Peninsula. One of the fossil-bearing levelswidely prospected are those of the late Cretaceous ?Maastrichtian? marine Lópezde Bertodano Formation, which are widely exposed at Seymour (= Marambio)Island. This highly fossiliferous levels are among the most productive sitesfor fossil remains in the Southern Hemisphere. Many vertebrate materialrecovered are fishes, which mainly encompass isolated chondrichthyans and teleosteanteeth, tooth plates, and vertebrae; many of which was recently described and/orreviewed. Despite the actinopterygians teeth and vertebrae record is extremelyabundant, it was mostly identified at generic orhigher taxonomical levels. In addition to thosematerial, a partial actinopterygian head was formally described and assigned toBeryciformes. Noteworthy, the upper levels of the López de Bertodano Formationhouse the extremely interesting fish bone layer associated to the K/Pg boundaryand the iridium anomaly. This fish bone layer crops out in a large extension inthe Seymour (=Marambio) Island. The fish material (skull bones and vertebrae)are preserved partially disarticulated in concretions and associated to amassive sediment containing charcoal and plant debris (fern, conifers, andangiosperms). Despite the concretions of the ?fish mass mortality layer? areextremely abundant in fish bones, which could be of taxonomic relevance, theseremains never were further studied. Other interesting marine Antarctic fish-bearinglocality is the Jurassic ?late Kimmeridgian-early Tithonian? Ameghino(=Nordenskjöld) Formation. The marine late Jurassic fishes from Antarctica are knownby few described actinopterygians. During the 2016 the Argentinian Antarcticfield expedition to Ameghino Formation recovered a taxonomically diverse actinopterygiansfauna which includes teleosteomorphs (pachycormiforms and aspidorhynchids),teleosts, and indeterminate actinopterygians. Thus, the last two ArgentinianAntarctic fieldtrips (2016-2017) provide new material on both, Jurassic andCretaceous fishes that improve the evolutionary history of Antarcticichthyofaunas. The main goal of this presentation is to summarize what we knowtoday about late Mesozoic (Cretaceous-Jurassic) fishes from the Larsen Basingiving an overview of the new findings and future research objectives inAntarctica.