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New materials of Masiakasaurus knopfleri Sampson, Carrano, and Forster, 2001, and Implications for the Morphology of the Noasauridae (Theropoda: Ceratosauria)

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Osteology of the noasaurid theropod Masiakasaurus knopfleri Sampson et al., 2001, is now two-thirds complete. We describe Masiakasaurus knopfleri in detail on the basis of examination of new specimens and emphasis on previously unknown elements. The skull is anteroposteriorly long but low in height, unlike the foreshortened abelisaurid condition. Premaxillary teeth are procumbent, like those of the dentary. Frontal bones are flat and unornamented, but the lacrimal and postorbital exhibit surface texturing. The braincase resembles that of abelisaurids but is more highly pneumatized. The neck is curved anteriorly but horizontal posteriorly, and it transitions to the trunk without significant proportional changes. Centrum pneumaticity appears confined to the neck and anterior trunk. The sacrum includes six vertebrae, and the expanded transverse processes of caudal vertebrae may articulate with caudal ribs. The scapulocoracoid is large and broad. The ilium is both anteroposteriorly long and dorsoventrally deep, and it bears pegs for articulation with sockets on the pubis and ischium, as in other ceratosaurs. The nearly complete pes shows no particular locomotor specializations and allows reinterpretation of the “raptorial” pedal ungual of Noasaurus as a manual element. These new specimens also illuminate the morphology of other noasaurids, especially those from the Lameta Formation. In addition to Madagascar, noasaurids are known from Europe, India, South America, and Africa, spanning at least Aptian–Albian through Maastrichtian time. The new materials of Masiakasaurus increase character resolution within Abelisauroidea, identifying many formerly equivocal features as synapomorphies of the nodes Noasauridae, Abelisauridae, or Abelisauroidea. Unfortunately, the fragmentary nature of nearly all other noasaurids obviates any meaningful ingroup resolution, and as a result no particular evolutionary or biogeographic scenarios for the clade can presently be supported (or rejected) with confidence.
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... Notably, they did not place those taxa within Noasauridae nor within the more inclusive clades Abelisauroidea (Bonaparte, 1991) or Abelisauria (Novas, 1992). Carrano et al. (2002) were the first to place Laevisuchus within Noasauridae, based on features of the cervical neural arch, a result backed up in subsequent phylogenetic analyses (Carrano & Sampson, 2008;Carrano et al., 2011). ...
... In the only review of the Indian Museum collection since Huene and Matley's (1933) seminal work, Novas et al. (2004) judged Compsosuchus solus and Jubbulpuria tenuis to be nomina dubia but deemed Laevisuchus indicus a valid taxon. Carrano et al. (2011) suggested that if the Lameta fauna of India is similar to the Maeverano fauna of Madagascar, then Compsosuchus, Jubbulpuria, and Laevisuchus may all represent the same taxon. ...
... And for those two species there is almost no understanding of either serial or ontogenetic variation in tooth shape, and it is extremely difficult to differentiate a tooth from a small-bodied species from that of a small individual (or replacement tooth) of a larger-bodied species. The Malagasy taxa Majungasaurus and Masiakasaurus are much more completely known than any Indian taxon, but serial and ontogenetic variation are only adequately known in the former (e.g., Smith, 2007); posterior maxillary or dentary teeth are not known yet for Masiakasaurus (Carrano et al., 2002(Carrano et al., , 2011. For these reasons, we consider the Kallamedu theropod tooth to be Neotheropoda incertae sedis pending further evidence. ...
... Notably, they did not place those taxa within Noasauridae nor within the more inclusive clades Abelisauroidea (Bonaparte, 1991) or Abelisauria (Novas, 1992). Carrano et al. (2002) were the first to place Laevisuchus within Noasauridae, based on features of the cervical neural arch, a result backed up in subsequent phylogenetic analyses (Carrano & Sampson, 2008;Carrano et al., 2011). ...
... In the only review of the Indian Museum collection since Huene and Matley's (1933) seminal work, Novas et al. (2004) judged Compsosuchus solus and Jubbulpuria tenuis to be nomina dubia but deemed Laevisuchus indicus a valid taxon. Carrano et al. (2011) suggested that if the Lameta fauna of India is similar to the Maeverano fauna of Madagascar, then Compsosuchus, Jubbulpuria, and Laevisuchus may all represent the same taxon. ...
... And for those two species there is almost no understanding of either serial or ontogenetic variation in tooth shape, and it is extremely difficult to differentiate a tooth from a small-bodied species from that of a small individual (or replacement tooth) of a larger-bodied species. The Malagasy taxa Majungasaurus and Masiakasaurus are much more completely known than any Indian taxon, but serial and ontogenetic variation are only adequately known in the former (e.g., Smith, 2007); posterior maxillary or dentary teeth are not known yet for Masiakasaurus (Carrano et al., 2002(Carrano et al., , 2011. For these reasons, we consider the Kallamedu theropod tooth to be Neotheropoda incertae sedis pending further evidence. ...
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ABSTRACT—Small-bodied theropod dinosaurs are rare on southern landmasses but have been known from India for a century. Excavations by Charles Matley and rgansankar Bhattacharji in uppermost Cretaceous sediments at Bara Simla, central India in 1917–1919 recovered small theropod vertebral and limb elements originally interpreted as coelurosaurians and separated into at least three species compsosuchus solus, Laevisuchus indicus, Jubbulpuria tenuis) based on features that can now be attributed to their serial position in the vertebral column. The comparatively recent discoveries of Noasaurus leali and Masiakasaurus knopfleri from similar-aged rocks in South America and Madagascar, respectively, and advances in basal theropod systematics led to a revised interpretation of most small-bodied Indian theropods as noasaurid abelisauroids. Here we review and redescribe Laevisuchus, Jubbulpuria, and Compsosuchus, including several elements that until now were thought lost, and describe a new partial noasaurid dentary from central India. The dentary bears the characteristic procumbent dentition of Masiakasaurus, which apparently is absent in Noasaurus. Likewise, cervical vertebrae of Laevisuchus more closely resemble those of Masiakasaurus than those of Noasaurus. Despite these similarities, phylogenetic analyses indicate that the balance of character data supports the Indian noasaurid species outside the sister-taxon pairing of South American and Malagasy species. Bones of small-bodied theropods have been recovered exclusively from the youngest Mesozoic localities in India (e.g., Pisdura, Bara Simla); to date they have not been reported from the slightly older localities in western and central India, from southern Indian sites in the Cauvery Basin, nor from the Vitakri Formation of Pakistan.
... Huinculsaurus, Masiakasaurus, Majungasaurus, Carnotaurus and Viavenator; Bonaparte et al., 1990;O'Connor, 2007;Carrano et al., 2011;Rauhut and Carrano, 2016;Filippi et al., 2018;Baiano et al., 2020Baiano et al., , 2023. Consequently, the well laterally projected parapophyses of Koleken are connected with transverse processes through a robust paradiapophyseal lamina, a feature also shared by several abelisauroids (e.g. ...
... Consequently, the well laterally projected parapophyses of Koleken are connected with transverse processes through a robust paradiapophyseal lamina, a feature also shared by several abelisauroids (e.g. O'Connor, 2007;Carrano and Sampson, 2008;Carrano et al., 2011;Farke and Sertich, 2013;Rauhut and Carrano, 2016;Baiano et al., 2020Baiano et al., , 2023Cerroni et al., 2020). The parapophyses, when well-preserved, show a teardrop-shaped outline pointing dorsally. ...
... The transverse constriction of the mid-sacral centra observed in Koleken (Fig. 8c) is a condition shared with several ceratosaurs, but unlike Masiakasaurus in which the centra have a similar width (Carrano et al., , 2011. The anteroposteriorly arched sacrum of Koleken is a widespread trait within Abelisauroidea (e.g. ...
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... Interestingly, a straight dorsal margin is also present in Genusaurus sisteronis, from the Albian of France, a possible furileusaurian (see below and [34]). It should be noted, however, that this character is also known in the noasaurid Masiakasaurus knopfleri [52]. ...
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... Noasauridae is a clade of theropod dinosaurs nested within Abelisauroidea mainly known by rather incomplete records from the Cretaceous of Gondwana. They are small to mediumsized dinosaurs with necks, arms, and skulls relatively longer than those of other abelisauroid clades (Carrano et al. 2011;Barbosa et al. 2023) and a species such as Vespersaurus paranaensis was not a top predator, having a possibly generalist diet and an opportunistic feeding strategy (Barbosa et al. 2023). ...
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The aeolian environments are often very restrictive to the preservation of fossil footprints. Dry sands and the low humidity substrate difficult the processes that allow the early cementation and prevent the destruction of the tracks by the wind erosion. Deflation of loose material from dry, uncemented sediments, transports away the clay and silt particles, and leaves only the sand and pebbles. These deposits, in the context of a hot and dry environment, show a narrow window of environmental conditions, which allow the footprints preservation. In the Early Cretaceous deserts of the central Gondwanaland existed well-adapted theropod communities to highly hot and arid climates. They are recognized, through ichnological data, as well as in the Sanfranciscana Basin, in the Paraná Basin (Botucatu Formation). In the Sanfranciscana Basin the dinosaur footprints occur in a context of humid interdune environment, in which isolated footprints and short theropod tracks were preserved.
... Pneumatic caudal vertebrae are so far unknown in Majungasaurinae, although only Majungasaurus was subjet to such type of study (O'Connor, 2007). Moreover, noasaurids such as Masiakasaurus or Vesperasaurus also have apneumatic caudal vertebrae (Carrano, Sampson & Forster, 2002;Carrano, Loewen & Sertich, 2011;Langer et al., 2019). Therefore, the presence of the pneumatic traits in the caudal series, at least in the anterior portion, could be a unique condition of brachyrostran abelisaurids within the clade Ceratosauria, although more studies using CT imaging are needed, especially among basal ceratosaurs, nosasaurids, majungasaurines, and more derived brachyrostrans. ...
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... The extension of temporal musculature on to a large portion of the dorsal surface of the frontal is characteristic of Theropoda (Currie, 1997;Wilson and Sereno, 1998). The contribution of the frontal to the orbital rim is strongly reduced, contrasting with the more anteroposteriorly elongate contributions of the frontal to the orbital rim seen in herrerasaurids (Sereno and Novas, 1993), coelophysoids (Rauhut, 2003), dilophosaurids (Rauhut, 2003), ceratosaurids (Rauhut, 2003;Pol and Rauhut, 2012), noasaurids (Xu et al., 2009;Carrano et al., 2011), early-branching coelurosaurs (e.g. Zuolong salleei: Choiniere et al., 2010;Rauhut et al., 2012), some tyrannosauroids (e.g. ...
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