Vol. 9, No. 8 August 1999 INSIDE • Mentor Opportunities, p. 3 • New CEO, p. 9 GSA TODAY • Fellows, Members, Student A Publication of the Geological Society of America Associates, p. 22 The Late Cretaceous Vertebrate Fauna of Madagascar: Implications for Gondwanan Paleobiogeography David W. Krause, Department of Anatomical Sciences, State University of New York, Stony Brook, NY 11794, [email protected] Raymond R. Rogers, Department of Geology, Macalester Figure 1. Reconstruction of Rahonavis College, 1600 Grand Avenue, St. Paul, MN 55105, ostromi, a primitive bird from the Late Cretaceous of Madagascar. [email protected] Only the bones shown in yellow Catherine A. Forster, Department of Anatomical Sciences, were found. Photo is of the State University of New York, Stony Brook, NY 11794, left hind foot skeleton in [email protected] dorsal view. Joseph H. Hartman, Energy and Environmental Research Center, University of North Dakota, Grand Forks, ND 58202, [email protected] Gregory A. Buckley, Roosevelt University, Evelyn T. Stone University College, Chicago, IL 60605, [email protected] Scott D. Sampson, Utah Museum of Natural History and Department of Geology and Geophysics, University of Utah, Salt Lake City, UT 84112, [email protected] ABSTRACT A rich, newly discovered assemblage of to the Late Cretaceous. The discovery of mam- exquisitely preserved vertebrate fossils from the Late mals, dinosaurs, and crocodiles in the latest Creta- Cretaceous of Madagascar provides an unparalleled ceous (Maastrichtian) of Madagascar that are closely opportunity to investigate the paleobiogeography of related to forms in India and South America reveals a Gondwanan landmasses. Most current plate tectonic cosmopolitanism at or near the close of the Cretaceous models depict widespread fragmentation of Gondwana prior that is paradoxical in the context of these models. INTRODUCTION The southern supercontinent of Gondwana fragmented into isolated landmasses during the Late Jurassic and Cretaceous, with dramatic consequences for the associated terrestrial and fresh- water vertebrate faunas. Reconstructions of the timing and sequence of this fragmentation are based almost entirely on geo- physical evidence and remain poorly tested paleontologically, primarily due to a sparse fossil record. The Mahajanga Basin Pro- ject, initiated in 1993 and conducted jointly by the State Univer- sity of New York at Stony Brook and the University of Antana- narivo (Madagascar), has recovered a diverse assemblage of vertebrates, including the primitive bird Rahonavis ostromi (Fig. 1), from the Upper Cretaceous Maevarano Formation, Mahajanga Basin, northwestern Madagascar (Fig. 2). This assemblage is one of the richest and best preserved yet known from the Mesozoic of Gondwana. It provides a new opportunity to elucidate distribu- tion patterns among Cretaceous vertebrates from Gondwana and, thereby, to test competing plate tectonic and biogeographic hypotheses. MALAGASY VERTEBRATE FOSSIL RECORD The Malagasy record of terrestrial and freshwater vertebrates Figure 2. Upper Cretaceous stratigraphy of the Mahajanga Basin. Inset: prior to the Late Cretaceous is sparse but improving, consisting of base map of Madagascar from Satellite Atlas of the World, 1998, National a diversity of primitive fishes, amphibians (including the frog-like Geographic Society, Washington, D.C., 222 p. Madagascar continued on p. 2 IN THIS ISSUE GSA TODAY August Vol. 9, No. 8 1999 The Late Cretaceous Vertebrate Fauna Rock Stars— Preston Cloud ..................... 16 of Madagascar: Implications for Letters .................................................... 18 GSA TODAY (ISSN 1052-5173) is published monthly Gondwanan Paleobiogeography ...... 1 by The Geological Society of America, Inc., with offices at 3300 Penrose Place, Boulder, Colorado. Mailing address: P.O. Box In Memoriam ......................................... 2 Birdsall-Dreiss Distinguished 9140, Boulder, CO 80301-9140, U.S.A. Periodicals postage Lecturer for 2000 Announced ................. 19 paid at Boulder, Colorado, and at additional mailing offices. J. John Sepkoski ...................................... 3 Postmaster: Send address changes to GSA Today, Member- GSAF Update .......................................... 20 ship Services, P.O. Box 9140, Boulder, CO 80301-9140. 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Also available on an annual CD-ROM, (together with GSA Bulletin, Geology, GSA Data Repository, and an Electronic Retrospective Index to Madagascar continued from p. 1 a result, the biogeographic origins of the journal articles from 1972); $89 to GSA Members, others call GSA Subscription Services for prices and details. Claims: highly endemic and imbalanced extant For nonreceipt or for damaged copies, members contact Triadobatrachus), and reptiles, as well as fauna, perhaps best represented by lemurs, Membership Services; all others contact Subscription Ser- spotty occurrences of dinosaurs, therap- remains shrouded in mystery. The late vices. Claims are honored for one year; please allow suffi- cient delivery time for overseas copies, up to six months. sids, and crocodiles (Fig. 3; Flynn et al., Pleistocene and Holocene record only 1998; Krause, 1999). Depéret (1896) was increases the level of endemism, as it STAFF: Prepared from contributions from the GSA staff and membership. the first to record Late Cretaceous verte- includes several giant lemurs, pygmy Executive Director: Sara S. Foland brates from the island. He described iso- hippopotami, the aardvark-like Plesioryc- Science Editors: Suzanne M. Kay, Department of lated turtle remains and, on the basis of teropus, and several other taxa unique to Geological Sciences, Cornell University, Ithaca, NY 14853; Molly F. Miller, Department of Geology, Box 117-B, Vanderbilt fragmentary bones and teeth, named two the island. University,