Late Campanian-Early Maastrichtian vertebrates from the James Ross Basin, West Antarctica: updated synthesis, biostratigraphy, and paleobiogeography

MARCELO REGUERO; GASPARINI ZULMA; OLIVERO EDUARDO; CORIA RODOLFO; FERNÁNDEZ MARTA; JOSE O´GORMAN; GOUIRIC-CAVALLI SOLEDAD; ACOSTA HOSPITALECHE CAROLINA; BONA PAULA; IGLESIAS ARI; GELFO JAVIER; EUGENIA RAFFI; MOLY JUAN JOSÉ; SANTILLANA, S.; MAGALÍ CÁRDENAS

ANAIS DA ACADEMIA BRASILEIRA DE CIENCIAS.

ACAD BRASILEIRA DE CIENCIAS

Lugar: Río de Janeiro; Año: 2022

0001-3765

The Snow Hill Island Formation (late Campanian - early Maastrichtian)crops out in the northeast of the Antarctic Peninsula and constitutes the basalpart of the NG Sequence being part of the transgressive sedimentation cycle ofthe James Ross Basin. Its major exposures occur at the James Ross (mainly inSanta Marta Cove, The Naze, and Hamilton Point areas), Vega (Cape Lamb andFalse Island Point), Humps, and Snow Hill islands. The Snow Hill IslandFormation (SHIF) comprises five members: Gamma, Hamilton Point (both lateCampanian-early Maastrichtian in age), Sanctuary Cliffs (early Maastrichtian),Cape Lamb (late Campanian? - early Maastrichtian), and Karlsen Cliffs (earlyMaastrichtian). Several fossil-bearing localities have been1. 11 identified inthe SHIF providing a valuable fauna of invertebrates and vertebrates, andflora. Our study focuses on the vertebrate fauna recovered at Gamma and CapeLamb members of the SHIF. The marine vertebrate assemblages include fishes(chondrichthyans and actinopterygians) and marine reptiles (elasmosauridplesiosaurs and mosasaurs). Also, a diverse terrestrial vertebrate assemblagehas been reported being characterized by pterodactyloid pterosaurs, dinosaurs(sauropod, elasmarian ornithopods, nodosaurid ankylosaur, and a paraviantheropod), and birds (gaviiforms and charadriiforms). Most SHIF dinosaurs shareclose affinities with penecontemporaneous taxa from Magallanes Region andPatagonia, indicating that at least some continental vertebrates could dispersebetween southern South America and Antarctica during the final stages of theMesozoic. Up to date, the Snow Hill Island Formation provides the most diverseLate Cretaceous marine and continental faunas from Antarctica. The presentstudy summarizes previous vertebrate findings with the best actualicedstratigraphical position, provides new records providing a more complete faunaassociation, and analyzes further perspectives.