New records of hexanchiform sharks (Elasmobranchii: Neoselachii) from the Late Cretaceous of Antarctica with comments on previous reports and described taxa

ABSTRACT

Sharks are virtually absent from coastal Antarctica since the Late Eocene glaciations, but this group exhibited a notable austral diversity during the Cretaceous and Paleogene. Several species have already been described from the Aptian-Eocene successions of the Larsen Basin exposed in the James Ross Island area (northern Antarctic Peninsula) and the predominantly deep-water Hexanchiformes have a record that, although still rare, has been continually increased. Four species of this group are currently known from that basin: Notidanodon pectinatus, Xampylodon dentatus, Rolfodon thompsoni, and Rolfodon tatere. Such records are especially concentrated in the Gamma Member of the Snow Hill Island Formation (or Herbert Sound Member of Santa Marta Formation), on James Ross Island. Here we described four teeth assigned to X. dentatus and one identified as R. tatere from upper Campanian sections of James Ross Island, highlighting the nomenclatural changes that led to the definition of Xampylodon and Rolfodon. Some specimens of X. dentatus presented here are considerably more complete or represent teeth of different positions than most previous records. The material assigned to R. tatere represents the oldest record of this species in the world, extending its time range by more than 10 million years.

KEYWORDS:

• James Ross Island
• James Ross Sub-basin
• Larsen Basin
• Late Cretaceous sharks
• Hexanchiformes

Acknowledgments

We thank several colleagues who shared the 43 days camping of the Brazilian Antarctic Program at James Ross Island in 2016 (January 06 to February 17), especially to the climber and photographer Edson Vandeira for the field support and help in collecting some of the data. We hearty thanks to Lars Arne Meier (Eberhard Karls University Tübingen, Germany) for discovering and saving tooth MN7590-V. Logistic support from the officers and crew of NApOc Ary Rongel (Brazilian Navy) is, as always, gratefully acknowledged. We are in debt to Jürgen Pollerspöck (shark-references.com), who kindly provided bibliographies of interest. Júlia d'Oliveira is thanked for the palaeoenvironmental illustration. We also thank to Dr. Henri Cappetta (Université de Montpellier, France) for the advice and helpful suggestions, and to Dr. Jürgen Kriwet, an anonymous reviewer and the editor of the NZJGG, who helped to substantially improve our manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data generated or analyzed during this work are included in the text, table, and figures. For additional information on the taxonomic history and other biological aspects of Hexanchiformes please consult the supplementary material openly available in zenodo at http://doi.org/10.5281/zenodo.7265898

 Google Scholar

.

Additional information

Funding

This work was supported by the National Council and Technological Development (CNPq) and the Brazilian Antarctic Program (PROANTAR) through Project FLORANTAR [Grant number 442765/2018-5PROANTAR/CNPq].