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 ampahan-taolana 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 mamp

The abelisaurid theropod Majungasaurus crenatissimus inhabited the plains of northwestern Madagascar during the Late Cretaceous. It lived alongside other nonavian dinosaurs, including a small-bodied noasaurid theropod (Masiakasaurus knopfleri) and a titanosaurian sauropod (Rapetosaurus krausei). Although an inhabitant of the expansive floodplains of the Mahajanga Basin, M. crenatissimus also frequented the broad and sandy channel belts that drained Madagascar's central highlands. These shallow rivers were populated by a variety of aquatic and semi-aquatic animals, including fish, frogs, turtles, and several species of both large and small crocodyliforms. These animals were likely adapted for seasonal fluctuations in water availability because the sediments that entomb their remains (fine-grained debris flow deposits intercalated with stream flow deposits) indicate a strongly variable discharge regime. Associated oxidized calcareous paleosols with localized accumulations of carbonate nodules suggest that the ambient climate was semiarid. The numerous bonebeds preserved in these same sediments are indicative of localized and recurrent pulses of mortality. M. crenatissimus fed on carcasses preserved in these bonebeds, and there is good indication from a wealth of tooth-marked bone derived from two conspecific individuals that it focused on the well-muscled axial skeleton in a fashion similar to that of many modern vertebrate carnivores. This evidence for intraspecific feeding renders M. crenatissimus the only theropod dinosaur with demonstrated cannibalistic tendencies.

MALAGASY ABSTRACT (FAMINTINANA)—Ny theropod abelisaurid Majungasaurus crenatissimus dia nonina tao amin'ny lemaky ny faritra avaratr'andrefan'i Madagasikara nandritry ny Cretaceous Farany. Tamin 'izany dia niara-nitoetra hatrany niaraka tamin'ny dinozaoro tsy avian izy, ka anisan'izany ny theropod noasaurid kely vatana (Masiakasaurus knopfleri) sy sauropod titanosaurian (Rapetosaurus krausei). Na dia nipetraka maharitra tao amin 'ny lemaka midadasika saforan'ny rano tao amin'ny Basin an'i Mahajanga aza M. crenatissimus dia hita matetika koa izy namonjy ny sisina lehibe sy mamasiky ny lakan-drano, izay manondraka ny anivon-tanin'i Madagasikara (central highlands). Ireo renirano marivo ireo dia nahitana karazam-biby maro izay monina manontolo na ampahany anaty rano, toy ny trondro, sahona, sokatra, ary karazam-boay maro koa ka hita tamin'izany ireo voay kely sy vaventy vatana. Ireo biby ireo dia toy ny lasa zatra niaina tamin'ny fiovaovan'ny fisian'ny rano satria ireo karazam-batokely madinika notanterin'ny rano izay nandrakotra sy nitahiry ny vatana mbola tavela tamin'izy ireo (tosak'ireo tatitra [sediment] potipotika tena madinika toa miendrika voa izay hifanelanelanan'ny tatitra nentin'ny rano) dia nampiseho mazava ny fisian'ny fiovaovana tamin'ny fametrahana ireo tatitra nentin'ny rano. Ny fisian'ny tany tranainy misy harafesina sy sokay ka niangonan'ny vonganana madinika misy carbonate tamin'ny faritra mazava dia nafahana nilaza fa ny toetr'andro sy toe-tany manodidina teo amin'io toerana io dia maina amin'ny ampahany. Ireo taolana maro hita tany amin'ny faritra ambany tamin'io tatitra io ihany koa dia karazana marika nilaza ny fisian'ny fahafatesana maro niaraka sy tampoka ary niverimberina matetita tamin'ny faritra mazava. M. crenatissimus dia nihinana ny vatan'ireo biby voatahiry izay hita tao amin'io toerana niangon'ny taolana io, ary nisy aza filazana mazava tamin'ny taolana nisy dia-nify mazava izay an'ny biby roa avy amin'ny karazan

Recent fieldwork in the Upper Cretaceous (Maastrichtian) Maevarano Formation, northwest Madagascar, has yielded important new skull material of the abelisaurid theropod, Majungasaurus crenatissimus. One of these specimens in particular—a virtually complete, disarticulated, and well preserved skull—greatly elucidates the craniofacial osteology of abelisaurids. Herein we describe the skull and lower jaws of this mid-sized theropod dinosaur. A number of features of the facial skeleton and cranium (as well as the postcranium) appear to result from increased levels of mineralization and ossification, which, at least in some instances, can be related directly to specific soft-tissue structures; examples include lacrimal-postorbital contact dorsal to the orbit, suborbital processes of the lacrimal and postorbital, presence of a mineralized interorbital septum, fused interdental plates, and mineralization of the overlying integument. Autapomorphic features include a highly derived nasal—greatly thickened and fused to its counterpart, with a large interior pneumatic chamber—and a median, ‘dome’-like thickening of the frontals, which appear to have been variably pneumatized by a paranasal air sac. Majungasaurus also possesses a derived suite of skull morphologies, including: a rostrocaudally abbreviated, dorsoventrally deep, and transversely broad skull; an expanded occiput, likely associated with expanded cervical musculature; short-crowned dentition; and an enlarged external mandibular fenestra consistent with a moderate degree of intramandibular movement or accommodation. A number of characters, present on both the skull and postcranial skeleton, suggest a divergent mode of predation relative to other, non-abelisaurid theropods.

MALAGASY ABSTRACT (FAMINTINANA)—Ireo asa fikarohana natao tao amin'ny Fiforonanana Maevarano tamin'ny vanim-potoana Cretaceous Ambony (Maastrichtian) tany amin'ny faritra avaratr'andrefan'i Madagasikara dia nahitana taolan-karan-doha vaovao tena sarobidy tokoa izay an'ny abelisaurid theropod, Majungasaurus crenatissimus. Iray tamin'ireo taolana ireo dia nisongadina satria saika feno tanteraka na tsy nitambatra tsara intsony aza dia tena voatahiry tsara io taolan-doha io, ka nahahana nampiseho mazava tsara ny fiforonan'ny taolan'ny loha sy ny tavan'ny abelisaurids. Koa eto izahay dia manazava ny taolan-doha sy ny valan-dranon'ny theropod dia ireo theropod dinozaoro izay manana vatana tsy lehibe nefa tsy kely koa. Maro amin'ireo toetran'ny taolan'ny endrika sy ny loha (sy ny aorinan'ny loha) dia ohatry ny vokatry ny fitombon'ny fivontoan'ny mineraly sy ny taolana, izay, farafahakeliny ho an'reo karazany sasany, dia azo heverina ho misy fifandraisany amin'ny firafitr'ireo rakotra malefaka miavaka; ohatra ny fifandraisan'ny lacrimal-postorbital aoriana amin'ny lavaky ny maso, ny vohitry ny suborbital-n'ny lacrimal sy ny postorbital, ny fisian'ny fvontosan'ny mineraly interorbital septum, fitambaran'ny taolam-pisaka manelana ny nify, ary fivontosan'ny mineraly tegument anatiny mipetraka ambony. Ireo toetra autapomorphic dia ahitana ireo taolan'orona nisy fivoarana be, izay manome endrika matevina sy mitambatra amin'ny lafiny mifanila aminy, ka ny endrika anatiny dia malalaka afaka hitoeran'ny rivotra, sy mitondra vohitra afovoany toa mampitombo ny fahatevenan'ny taolan'andrina, izay toa milaza fa toa afaka nitoeran'ny rivotra noho ny paranasal izay kitapon-drivotra. Majungasaurus koa dia manana endriky ny fivoaran'ny karan-doha, ka anisan'izany ny fihenan'ny rostro aoriana, lalina ny faritra afovoany-aoriana, sy mivelatra ny sisin'ny karan-doha, mivelatra ny occiput, izay mampiseho ny toetra mafonja ny hozatry ny loha; boribory-fohy ny nify; ary mivelatra ny mandibular fenestra ivelany mifanaraka amin'ny fahafahan'ny fihetsehana na

Despite the known diversity of abelisaurid theropod dinosaurs, their dental anatomy remains poorly understood. Discoveries of elements preserving in situ dentition of the Late Cretaceous (Maastrichtian) Malagasy taxon Majungasaurus crenatissimus, coupled with recent progress in morphometric analysis of theropod teeth, provide an opportunity to document dental morphology and quantitatively evaluate positional variation in an abelisaurid dentition. Majungasaurus possesses an unusually static dental formula of 4/17/17 and a relatively even pattern of tooth replacement. The teeth are brachydont, moderately heterodont, and exhibit fairly well-developed interdenticular sulci/caudae. The premaxillary teeth are significantly wider, more elongate, and less curved than those in the maxilla and dentary, whereas the dentary crowns are shorter and more ‘squat’ than those in the upper dentition. Knowledge gained from teeth preserved within jaws demonstrates that isolated crowns recovered from the same deposits in the Maevarano Formation of the Mahajanga Basin, and assigned to Majungasaurus by earlier workers, can be confidently referred to that species. Qualitative and quantitative differences are demonstrated between the teeth of Majungasaurus and those of the only other known non-avian theropod in the Maevarano assemblage, the noasaurid Masiakasaurus knopfleri. Documentation of the intra-individual and intraspecific variation in Majungasaurus tooth anatomy provides a standard against which other abelisaurids can be compared and provides a suite of dental features that potentially can be used to assist in evaluation of the phylogenetic position of Majungasaurus among abelisaurids and Abelisauridae among theropods.

MALAGASY ABSTRACT (FAMINTINANA)—Na dia efa fantatra aza ny fisian'ny dinozaoro theropod maro karazana, dia mbola azo lazaina fa kely ihany no fantatra momba ny fiasa sy firafitry ny nifin'izy ireo. Ireo karazana vokatra azo tamin'ny asa fikarohana voatahiry ka nahita nify tao amin'ny Cretaceous Farany (Maastrichtian) Malagasy sokajy Majungasaurus crenatissimus, izay niaraka tamin'ny fivoaran'ny fikarohana momba ny refy isan-karazany izay vao tsy ela akory no natao tamin'ny nifin'ny theropod dia nanome fahafahana nahazoana nanangona tahirin-kevitra momba ny endriky ny nify sy nanao fanombana tamin'ny alalan'ny marika ny fahasamihafana hita teo amin'ny fomba fipetraky ny nify teo amin'ny abelisaurid. Majungasaurus dia manana tarehi-marika raikitra momba io nify io izay tsy fahita loatra dia 4/17/17 and toa misy endrika manokana koa aza tamin'izany ho an'ireo nify mpisolo. Ny nifiny dia « brachyodont », sy maka endrika kely « heterodont » koa, ary ahitana mazava « sulic/caudae » manelanelana ny nify. Ireo nify anoloana amin'ny vazana ambony dia hita mazava ho mivelatra sy lavalava kokoa, ary tsy dia mifaingoka loatra raha ampitahaina amin'ireo aty aoriana amin'iny vazana ambony iny ihany, fa ny tendron-nify kosa dia fohy sy iva ary mitombona kokoa raha oharina amin 'ireo tapany ambony amin'ny ankapobeny. Ny fahaizana azo tamin'ny alalan'ireo nify tsara tahiry hita tamin'ny valandrano (jaw) dia nampiseho tamin'ny alalan'ny satro-nify hita nitokana izay tafaraka tamin 'ny tatitra (deposits) tao amin'ny Fiforonana Maevarano tao anatin'ny Basin an'i Mahajanga, izay efa nambaran'ireo mpikaroka teo aloha ho Majungasaurus, dia ahafahana milaza marina fa io karazany io ihany izany. Ny tenako koa dia afaka mampiseho ny tsy fitoviana, na amin'ny toetra ivelany na amin'ny fomba azo refesina, misy eo amin'ny nifin'ny Majungasaur

Recent fieldwork in Upper Cretaceous terrestrial deposits in northwestern Madagascar has yielded a remarkable diversity of vertebrates, including several specimens of the abelisaurid theropod Majungasaurus crenatissimus (Deperet, 1896) Lavocat, 1955. Featured among the discoveries is an exquisite specimen (UA 8678) that preserves a virtually complete precaudal vertebral column, numerous costal elements, and portions of the skull and appendicular skeleton. This contribution represents the first description highlighting the postcranial axial skeleton of Majungasaurus. Owing to the completeness and quality of preservation, this specimen allows an examination of the serial transformation of features along the length of the axial skeleton, including a detailed analysis of postcranial pneumaticity in a nontetanuran theropod. Notable features of Majungasaurus include pneumatic cervical ribs with caudally bifurcate shafts and extensive pneumaticity of all postatlantal, precaudal vertebrae. Several postcranial features exhibited by Majungasaurus—including a well-developed cervical epipophysis, laterally expanded dorsal parapophysis, and sub-divided infradiapophyseal fossa in middle dorsal series—support previous phylogenetic studies placing it within Abelisauroidea and Abelisauridae. Majungasaurus (and abelisaurids generally) exhibit a robust cervical skeleton that features tightly interlocking cervical ribs, hyperossification of cervical rib shafts, and hypertrophied muscle attachment sites relative to other basal theropods. These features together highlight an axial core constructed to withstand high stresses, likely reflecting feeding adaptations for predation on large-bodied prey.

MALAGASY ABSTRACT (FAMINTINANA)—Ireo fikarohana natao tamina faritra misy tany iangonan'ireo taolam-balon-javamananaina tamin'ny vanim-potoanan'ny Cretacées Ambony tany amin'ny faritra avaratra andrefan'i Madagasikara iny dia nahafahana nanampongatra karazana sisan-dinaozora misy karazany marobe, ahitana sisana abelisaurid theropod Majungasaurus crenatissimus misimisy (Depéret, 1896) Lavocat, 1955. Isan'ireo voka-pikarohana misongadina amin'izany ny sisan-javamananaina (UA 8678) iray izay mbola feno ny taolan-katoka mitondra mitohy amin'ny hazondamosiny rehetra, ny taolan-tratrany maromaro, ny ampahany amin'ny karan-dohany ary ny taolan-drambony. Maneho ny fanoritsoritana voalohany ny taolan-damosina ao am-para-hatoky ny Majungasaurus io vokam-pikarohana io. Satria mbola voatahiry tsara sy mbola eo daholo ny singan-javatra rehetra momba azy, dia ahafahana mandinika ireo dingampivoaran'ny endriky ny taolan-damosiny ity sisan-javamananaina ity, ka tafiditra ao anatin'izany ny fandinihana lalina kokoa ny fiangonan'ny rivotra ao am-para-hatoka-na ‘nontetanuran’ theropod. Isan'ny ireo zavatra mampiavaka ny Majungasaurus ny fananany taolan-katoka madinika iangonan-drivotra izay manana tandrony mizara roa ary mahafoka rivotra be tokoa amin'ny taolan-damosiny rehetra. Maro amin'ireo toetoetran'ny farahatokin'ny Majungasaurus, ohatra ny fivontosana be eo amin'ny vohitra ‘épipophyse'-ny hatoka, ny fivelaran'ny vohitra 'parapophyses'aoriana amin'ny lafiny havia sy havanana, ny fizarazaran'ny lavaka eo ambanin'ny 'diapophyse’ dia manamafy ireo fandinihina ‘phylogenetic’ nametraka azy ao amin'ny fianakavian'ny Abelisauroidea sy Abelisauridae.