New fossil vertebrates from the López de Bertodano Formation (Maastrichtian), Seymour (Marambio) Island, Antarctica

JOSE O´GORMAN; BONA, P.; DE LOS REYES, ; SANTILLANA, S.; GOURIC-CAVALLI SOLEDAD; ARI IGLESIAS; MOLY, J.J.; TALEVI M.

Leuven

Congreso; XIIth Biology Symposium of the Scientific Committee of Antarctic Research; 2017

Scientific Committee on Antarctic Research

The Seymour (Marambio) Island, located in the James Ross Archipelago,is one of the richest vertebrate bearing locality of Antarctica. Most of thefossil vertebrates registered come from several Cretaceous levels of the Lópezde Bertodano Formation (Maastrichtian 65,5-68,7ma). This formation could be divided in to two informal units: 2-6 (Rotularia Units), deposited in a shallowdelta/estuary influenced marine environment, and 7-10 (molluscan Units),deposited in a shelf environment. During the past forty years paleontologicalprospection supported by the Instituto Antártico Argentino (IAA) have provided several fossil remains including marine vertebrates and birds. Here wereport the results of the last 2017 Antarctic fieldtrip, which provides newmaterial of chondrichthyans (chimaeras and sharks ; units 7, 8, 9),actinopterygians (unit 9), mosasaurs (units 7, 8, 9), plesiosaurs (units?), and birds (units 8, 9). Among plesiosaurs, cranial andpostcranial elements of a long necked non-aristonectine elasmosaurid where collectedassociated to the K/P boundary. The specimen preserve a sub articulated butincomplete postcranium and part of the cranium and mandible. The mandibular symphysisis extremely short comprising only 2 alveoli. This new plesiosaur material indicates a higher diversityof non aristonectine elasmosaurids than that known for Latest Cretaceous marineenvironments at high latitudes.