Tuesday, July 1, 2014

[PaleoIchthyology • 2012] Bawitius gen. nov. • A Giant polypterid (Osteichthyes, Actinopterygii) from the Upper Cretaceous Bahariya Formation of Egypt

Bawitius bartheli (Schaal 1984)

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.

syn: Polypterus bartheli (Schaal 1984)
 locality: Bahariya Formation, in the Bahariya Oasis of western Egypt

Barbara S. Grandstaff, Joshua B. Smith, Matthew C. Lamanna, Kenneth J. Lacovara, Medhat Said Abdel-Ghani. 2012. Bawitius, gen. nov., A Giant polypterid (Osteichthyes, Actinopterygii) from the Upper Cretaceous Bahariya Formation of Egypt. Journal of Vertebrate Paleontology. 32(1):17-26. DOI: dx.doi.org/10.1080/02724634.2012.626823