To M.Buono and C.Acosta Hospitaleche for the discussion on some of the issues discussed here,which improved the quality of this work.Ariel Aresti(Museo Egidio Feruglio,Trelew,Argentina)is thanked for the preparation of the thoracic vertebra.We thank Dr.Daphne Lee and Marcus Richard(Geology Museum,University of Otago,New Zealand)and Dr.Annelise Folie(Royal Belgian Institute of Natural Sciences,Museum of Natural Sciences,Brussels,Belgium)for providing photographs of the dermochelyid specimens under their care.Eugenia Raffi is specially thanked for her help during the study of this specimen in the CADIC.We also thank C.Acosta Hospitaleche for her invitation to participate in the Special Volume of"Advances in Polar Science".We acknowledge the revision of one anonymous reviewer and Dr.James Parham as reviewer whose comments help to improve the quality of this manuscript.Finally,we want to thank M.López Cabrera for her collaboration in the field work and to Z.Gasparini for her valuable contribution to this study.This research was partially funded by the Agencia Nacional de Promoción Científica y Tecnológica-Proyectos de Investigación Científica y Tecnológica-PICT 2017-0607(to M.Reguero)and PICT 2019-00327(to M.Buono). （Museo Egidio Feruglio,Trelew,Argentina）