Bawitius, gen. nov., a giant polypterid (Osteichthyes, Actinopterygii) from the Upper Cretaceous Bahariya Formation of Egypt

ABSTRACT

A newly discovered osteichthyan ectopterygoid from the Upper Cretaceous (lower Cenomanian) Bahariya Formation of the Bahariya Oasis, Egypt, is nearly identical to the holotypic specimen of Polypterus? bartheli from the same area and geologic unit. The Bahariya ectopterygoids are referable to Polypteridae based on the presence of a robust, laterally directed process that articulates with the maxilla. Additionally, ganoid scales from the Bahariya Formation have an isopedine layer, a histological character of Polypteriformes; but differ from those of previously described members of this clade in having a discontinuous ganoin layer, rectilinear shape, and proportionally small articular processes. Both the ectopterygoids and the scales are unusually large, and are the only polypteriform remains so far identified from the Bahariya Formation. The ectopterygoids and (tentatively) the scales are herein assigned to a single species of gigantic polypterid, the morphology of which is sufficiently distinctive to warrant its placement in a new genus, Bawitius, gen. nov. Differences in scale anatomy and the enormous disparity in body size between Bawitius and Serenoichthys support the hypothesis (originally proposed on the basis of varied fin spine morphologies) that a diversity of polypterid fishes inhabited North Africa during the early Late Cretaceous.

ACKNOWLEDGMENTS

We thank P. Dodson, J. Poole, R. Giegengack, A. Swedan, K. Soleiman, Y. Attia, Y. Abdelrazik, J. R. Smith, J. Caton, A. Tumarkin-Deratzian, J. Harris, S. Kurth, P. Kane-Vanni, J. Lacovara, K. Johnson, D. Nichols, M. Lyon, J. Losos, W. Dominik, P. Luger, X. Sun, A. López-Arbarello, the Egyptian Mineral Resources Authority (formerly the Egyptian Geological Survey and Mining Authority), and the El Beshmo Lodge for invaluable assistance both in and out of the field. We thank M. Friedman, A. Berta, and P. Barrett for editorial guidance, and A. Murray and L. Cavin for their helpful reviews of an earlier version of the manuscript. The BDP has been supported by grants to J.B.S. from Cosmos Studios, MPH Entertainment, the University of Pennsylvania, the Andrew W. Mellon Foundation, and the Delaware Valley Paleontological Society, and to P. Dodson (Penn) from the late E. de Hellebranth and the University of Pennsylvania. This paper is BDP contribution 7.

Handling Editor: Matt Friedman