First pachycormiform (Actinopterygii, Pachycormiformes) remains from the Late Jurassic of the Antarctic Peninsula and remarks on bone alteration by recent bioeroders

ABSTRACT

We describe osteichthyan remains from the Upper Jurassic of the Ameghino (= Nordenskjöld) Formation of the Antarctic Peninsula. The fossils are referred to a suspension-feeding pachycormid based on the shape, morphology, and presence of acus fanunculi (needle teeth) on their gill rakers. Due to the fragmentary condition of the Antarctic material, we refer it to aff. Asthenocormus. The remains described here represent the first record of a suspension-feeding pachycormid from the Upper Jurassic of the Antarctic Peninsula and the oldest pachycormid yet recovered from Antarctica. The new fossil fish supports a possible early dispersal route through the Mozambique Corridor (= Trans-Gondwana or South African Seaway). We also describe the weathering produced by modern lichens, which might be misinterpreted as original bone structure.

ACKNOWLEDGMENTS

This contribution was mainly funded by the Dirección Nacional del Antártico and the Instituto Antártico Argentino, project: PICTO 2010-0093. Partial funding was provided by the Consejo Nacional de Investigaciones Científicas y Tecnológicas, Agencia Nacional de Promoción Científica y Tecnológica, and the Universidad Nacional de La Plata through PICT 2015-0253 to S.G. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We especially thank J. P. O’Gorman (Universidad Nacional de La Plata) for valuable comments on a previous version of the manuscript. We thank J. P. O’Gorman, J. J. Moly, and L. Acosta Burllaile (Universidad Nacional de La Plata) for their valuable assistance in the field; F. Medina (Universidad Nacional de Buenos Aires) for providing valuable information of the study locality and valuable literature; L. Pérez for discussion on the EDX profiles; the scanning electron microscopy and microanalysis service (SeMFi-LIMF), Facultad de Ingeniería, UNLP; the logistic support of the Fuerza Aérea Argentina (Dotación 47°); C. Amenábar (IAA), who is responsible for loaning and providing access to fossil specimens at the Repositorio Antártico de Colecciones Paleontológicas y Geológicas of the Instituto Antártico Argentino; P. Fontana, S. Santillana, and Rodolfo del Valle (DNA-IAA) for providing valuable literature; the reviewers, J. Kriwet and J. J. Liston, for suggestions and comments that greatly improved the quality of the manuscript; and the editor L. Sallan.