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1 June 2007 DENTAL MORPHOLOGY AND VARIATION IN MAJUNGASAURUS CRENATISSIMUS (THEROPODA: ABELISAURIDAE) FROM THE LATE CRETACEOUS OF MADAGASCAR
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Abstract

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

JOSHUA B. SMITH "DENTAL MORPHOLOGY AND VARIATION IN MAJUNGASAURUS CRENATISSIMUS (THEROPODA: ABELISAURIDAE) FROM THE LATE CRETACEOUS OF MADAGASCAR," Journal of Vertebrate Paleontology 27(sp8), (1 June 2007). https://doi.org/10.1671/0272-4634(2007)27[103:DMAVIM]2.0.CO;2
Accepted: 5 January 2007; Published: 1 June 2007
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