Overview of the History of Discovery, Taxonomy, Phylogeny, and Biogeography of Majungasaurus Crenatissimus (theropoda: Abelisauridae) from the Late Cretaceous of Madagascar

We review the historical sequence of discoveries of Majungasaurus crenatissimus, an abelisaurid theropod from the Upper Cretaceous (Maastrichtian) Maevarano Formation, Mahajanga Basin, northwestern Madagascar. For almost a century, beginning in 1895, periodic expeditions conducted by French, Japanese, and Malagasy teams yielded fragmentary and isolated remains of a medium-sized theropod dinosaur from the Maevarano Formation. These materials were first assigned to Megalosaurus crenatissimus but later to Dryptosaurus crenatissimus, then Majungasaurus crenatissimus, and, most recently, Majungatholus atopus. The taxon was variously considered to pertain to Tyrannosauridae, “Megalosauridae,” and Abelisauridae. Recent excavations undertaken by the Mahajanga Basin Project (1993 to present) have resulted in abundant and spectacular remains of this theropod. The new material allows us to establish Majungasaurus crenatissimus as the valid name for this theropod and to conclusively place it within Abelisauridae. M. crenatissimus is currently known from multiple specimens of various size (and presumably age) classes, which cumulatively represent the great majority of the skull and skeleton. Together, these finds establish Majungasaurus as among the best known of Gondwanan theropods. M. crenatissimus is one of several vertebrate taxa recovered from the Maevarano Formation that indicate close biogeographic ties linking Madagascar with the Indian subcontinent and South America. These data support the hypothesis of a high degree of cosmopolitanism among these landmasses, the result of a persistent subaerial connection between Indo-Madagascar to the east and South America to the west (possibly through Antarctica) until sometime late in the Late Cretaceous. MALAGASY ABSTRACT (FAMINTINANA)—Nanao jery todika ireo tantara nitranga sy nifanesy tamin’ny fahitana ny Majungasaurus crenatissimus, izay abelisaurid theropod hita tao Cretaceous Ambony (Maastrichtian) tao amin’ny Forona (Formation) Maevarano, ao amin’ny Basin an’i Mahajanga, amin’iny faritra avaratr’andrefan’i Madagasikara iny izahay. Efa ho zato taona teo ho eo izao, izay nanomboka ny taona 1895, tamin’ny fidinana an-tsaha isaky ny fotoana voatondro izay notarihin’ny mpikaroka nitambaran’ny Frantsay, sy Japone, ary Malagasy no nahitana silaka sy ampahantaolana an’ireo dinozaoro theropod manana vatana salan-tsalany hita tao amin’ny Forona Maevarano. Tamin’ny alalan’ireo taolana ireo no namaritana an’i Megalosaurus crenatissimus tamin’ny voalohany ary taorian’izay koa i Dryptosaurus crenatissimus, ary nanaraka i Majungasaurus crenatissimus, ary vao haingana dia Majungatholus atopus. Ny taxon dia nojerena tamin’ny fomba maro samihafa mba hampisehoana ireo izay mitovy sy mifanakaiky amin’ny Tyrannosauridae, “Megalosauridae,” ary Abelisauridae. Tamin’ny alalan’ny fandavahana an-tsaha nataon’ny “Mahajanga Basin Project” nanomboka tamin’ny taona 1993 ka hatramin’izao dia nahita taolana maro sy nahaliana an’io karazana theropod io. Ireo karan-taolana vao hita ireo no nahafahanay nanome ny tena anarana raikitra an’i Majungasaurus crenatissimus ho an’io theropod io sy nametrahana azy ho anisan’ny Abelisauridae. Amin’izao fotoana izao M. crenatissimus dia fantatatra tamin’ny alalan’ireo fahitana maro karazana izay manana habe samihafa (izay azo heverina mamaritra koa ny taona), ka raha atambatra dia mampiseho ny ankamaroan’ny taolan’ny loha sy ny vatana. Ny fitambaran’ireo taolana ireo dia nahafahana nilaza ihany koa fa Majungasaurus dia anisan’ireo theropod-n’i Gondwana tena tsara fantatra indrindra. Majungasaurus koa dia iray amin’ireo karazam-biby manana hazon-damosina (vertebrate taxa) hita tao amin’ny Forona Maevarano izay mampiseho ny tsy fahalaviran’i Madagasikara ara-jeografian’ny zava-manan’aina ka nifandraisany subcontinent-n’i Inde sy Amerika Atsimo. Ireo angonam-pikarohana (data) ireo dia manohana ny fiheverana (hypothesis) ny fisiana karazam-pihavian’aina maro dia maro sy samihafa hita tao amin’ireo vongan-tany ireo, izay vokatry ny fitohizana nitohy teo amin’ny Inde sy Madagasikara tany atsinanana ary Amerika Atsimo tany andrefana (izay mety ho tamin’ny alalan’i Antarctica) hatramin’ny faraparan’ny “Late Cretaceous.”