ROmain Vullo

Eric Buffetaut, Michael J. Everhart

Academic paper

Journal of Vertebrate Paleontology

32

5

1198-1201

Gwawinapterus beardi was described as an istiodactylid pterosaur on the basis of a single fragmentary toothed upper jaw (premaxilla-maxilla) from the late Campanian marine strata of the Northumberland Formation of Hornby Island, British Columbia (Canada), and was thus regarded as the latest known toothed pterosaur in the world (Arbour and Currie, 2011a). Therefore, the interpretation and the conclusion of Arbour and Currie (2011a) implied the existence of a 40-million-year range extension for Istiodactylidae. This specimen (RBCM.EH2011.003.0001, previously VIPM 1513; see Arbour and Currie, 2011b) is poorly preserved, being embedded in a concretionary nodule and having been split in half (Figs. 1, 2A). Here we argue that the identification as pterosaur is erroneous and that this jaw fragment belongs instead to a saurodontid fish, a widespread group of predatory teleosteans (Ichthyodectiformes) particularly well represented in the Late Cretaceous of North America. Indeed, most of the known material has been recovered from the Western Interior Seaway and Gulf Coastal Plain deposits (Shimada and Fielitz, 2006; Schein and Lewis, 2007). The present reinterpretation is based on several anatomical observations and comparisons with published and unpublished material, and is further supported by the stratigraphic context of this fossil. Lastly, saurodontids were exclusively marine fishes and this reappraisal agrees with the likely paleoenvironmental setting of the Northumberland Formation deposits. The first saurodontid remains were originally described by Harlan (1824) and Hays (1830), who erected the genera Saurocephalus and Saurodon, respectively. Both genera were described on the basis of incomplete cranial material (including jaws and teeth), and both authors erroneously considered that these vertebrates belonged to the �Enaliosauria� of Conybeare (i.e., an old taxon name meaning �marine lizards,� in which plesiosaurs and ichthyosaurs were originally grouped). The teleostean nature of Saurocephalus and Saurodon was recognized by Agassiz (1843:101�103, pl. 25c). Institutional Abbreviations

English