Endocranial morphology of Pygoscelis calderensis (Aves, Spheniscidae) from the Neogene of Chile and remarks on brain morphology in modern Pygoscelis

Abstract

The endocranial anatomy of Pygoscelis calderensis, a fossil species from the Bahía Inglesa Formation (Middle Miocene–Pliocene) of Chile, South America, was described through CT scans. Reconstructions of the fossil P. calderensis and endocasts for the living Pygoscelis adeliae, and Pygoscelis papua are provided here for the first time. Comparisons with the extant congeneric species P. adeliae, Pygoscelisantarctica and P. papua indicate that the morphological pattern of the brain and inner ear of the extant pygoscelids has been present already in the Middle Miocene. The neurological morphology suggests that the paleobiology of the extinct form would have been similar to the extant species. It was probably true for diet, feeding behaviour and diving kinematics.

Keywords::

• braincase
• cranial endocast
• inner ear
• Pygoscelis
• South America

Acknowledgements

The authors thank Dr D. Rubilar-Rogers (MNHN) and Dra. M. Picasso (MLP) for the access to the materials under their care. The authors thank the reviewers P. Jadwiszczak (Uniwersytet w Białymstoku, Poland) and RE Fordyce (Smithsonian Institution, USA), whose comments improved this manuscript. The authors also thank Agencia Nacional de Promoción Científica, Tecnológica and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (APC and CAH), and CONICYT (R.E.Y-Y) for constant support. Finally, the authors thank Dr A. Carlini (MLP) and B. Lafuente (Fundación Arturo López Pérez, Santiago) for the tomographies and Dr P. Currie (University of Alberta) for the access to the software used to create 3D models.