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1 June 2007 THE POSTCRANIAL AXIAL SKELETON OF MAJUNGASAURUS CRENATISSIMUS (THEROPODA: ABELISAURIDAE) FROM THE LATE CRETACEOUS OF MADAGASCAR
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Abstract
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. Majungasaurus (sy abelisaurids amin'ny ankapobeny) dia mampiseho taolan-katoka matanjaka narafitra mafy manodidina sy mifehy ny fihetsehin'ny taolan-katoka, sy ny fivontosan'ny vantan-taolana ary ny fihenana be dia be ny hozatra mifandray aminy raha ampi-tahaina amin'ireo faritra amin'ny vatana ambany eo amin'ny theropods. Ny fananany ireo toetra ireo mitambatra dia mampisongadina ny fisihan'ny andry voarafitra ahazakany fisehoan-javatra sarotra sy manahirana, toy ny fahazarana amin'ny fihinanana haza vaventy vatana.
and O'C. O. N. N. O. R. PATRICK M. "THE POSTCRANIAL AXIAL SKELETON OF 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[127:TPASOM]2.0.CO;2
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