The Mahajanga Basin Project (MBP), since its inception in 1993, has been conducted jointly with the University of Antananarivo. Our discoveries, most of them in the Maevarano Formation near the village of Berivotra in northwestern Madagascar, have established the island as having some of the most complete and scientifically significant specimens of Late Cretaceous vertebrate animals from the southern hemisphere and, indeed, the world. These discoveries have more than quintupled the previously known diversity of Late Cretaceous vertebrates from Madagascar and now include the remains of approximately 50 species of bony fishes, frogs, turtles, lizards, snakes, crocodyliforms, non-avian dinosaurs, birds, and mammals. Many of the specimens recovered represent species that are new to science, and many of the higher taxa represented are the first documented occurrences for the pre-Late Pleistocene of Madagascar. Other records represent the only known occurrences from Madagascar, fossil or recent (e.g., rays, sawsharks, albuloids, lepisosteids among fishes, ceratophyrines among frogs, and gondwanatheres and marsupials among mammals). Finally, some of the higher taxa represented constitute first records from the Late Cretaceous of large portions of the southern supercontinent Gondwana (e.g., sawsharks, frogs, lizards, birds, marsupials).
Research on these various discoveries has provided, and continues to provide, important information on the anatomy, habits, and relationships of many taxa, documentation of the geological structure and history of the Mahajanga Basin, key insights into the biogeographic origins of both the extinct and extant vertebrate faunas of the island, and crucial new implications for the plate tectonic history of Gondwana during the Mesozoic Era. It is during the latter half of this era that Gondwana began to fragment, with dramatic consequences for its terrestrial and freshwater vertebrate fauna. Madagascar is of unusually high paleobiogeographic interest and intrigue because: (1) it occupied a somewhat central geographic position within Gondwana and was among the first, and last, landmasses to be involved in fragmentation of the supercontinent; (2) it has been isolated from all other Gondwanan landmasses for over 85 million years; (3) it has a highly endemic and imbalanced extant biota whose biogeographic origins remain one of the greatest unsolved mysteries of natural history; and (4) its fossil record of terrestrial and freshwater vertebrates is extremely sparse.
Many of the taxa that we have discovered in the Late Cretaceous of Madagascar have their closest relatives on the Indian subcontinent and in South America, thus revealing a much higher degree of cosmopolitanism among Gondwanan vertebrates near the end of the Late Cretaceous than predicted by generally accepted paleogeographic reconstructions. Furthermore, it appears that the Late Cretaceous Malagasy vertebrate fauna went extinct without issue and that the basal stocks of the extant Malagasy fauna arrived after the Late Cretaceous. If so, and in light of the fact that Madagascar was isolated in the Indian Ocean for some 20 million years prior to the end of the Cretaceous, each of the founding populations would have had to cross a formidable marine barrier.
The MBP has been funded by the US National Science Foundation (1993–94, 1995–97, 1997–2001, 2001–2004, 2005–2010), the National Geographic Society (1999–2000, 2001–2003, 2004–2005, 2009–2010), the Dinosaur Society (1995), and the Simons Foundation (2007–2008).