Youngest jalodontid shark from the Triassic of Europe and a revision of the Jalodontidae

ABSTRACT

Phoebodont-like teeth originally described as Phoebodus brodiei and Phoebodus keuperinus from the Upper Triassic of England and Germany, respectively, are attributed to a new genus Keuperodus of the family Jalodontidae. The characteristic features of all jalodontid genera are re-examined leading to the conclusion that this group formed a separate, distinct chondrichthyan evolutionary line for which a new order, the Jalodontiformes is established. The jalodontid dentition evolved from a homodont-like type to one which was markedly heterodont.

ACKNOWLEDGMENTS

The authors are grateful to R. Böttcher (Staatliches Museum für Naturkunde, Stuttgart, Germany) for providing A. Seilacher’s specimens for study and microphotography; to E. Nitsch (Landesamt für Geologie, Rohstoffe und Bergbau, Freiburg, Germany) for stratigraphic data on the Triassic locality of Germany; to A. Alekseev, L. Kononova, and A. Reimers (Department of Paleontology, Geology Faculty, Lomonosov Moscow State University, Moscow, Russia), M. Nestell and G. Nestell (Department of Earth and Environmental Sciences, University of Texas at Arlington, Arlington, U.S.A.) for processing the samples and extracting the contained fish microremains; to G. Cuny (Université Claude Bernard Lyon 1, Villeurbanne, France) for providing the Greenland specimens of Adamantina benedictae from the Natural History Museum of Denmark for study; to S. Nilov (Institute of Earth Sciences, St. Petersburg State University, St. Petersburg, Russia) for microtomographic sections and reconstruction; to R. Rakitov (Borissiak Paleontological Institute of the Russian Academy of Sciences, Moscow, Russia) and N. Vlasenko (Research Park, St. Petersburg State University, St. Petersburg, Russia) for assistance during SEM imaging; to B. Clark (Core Research Laboratories/IAC, Natural History Museum, London, U.K.) for µ-CT scanning the NHMUK specimens and advice on virtual imaging. The scientific research completed by AI was performed at the Center for Geo-Environmental Research and Modeling (GEOMODEL) and the Center for X-ray Diffraction Studies of Research Park of St. Petersburg State University. The paper has been supported partly by the Kazan Federal University Strategic Academic Leadership Program. We thank reviewers E. Manzanares and G. Cuny, and editors J. Kriwet and J. Harris for making important suggestions and comments which helped us to improve the manuscript.