Abelisauridae Bonaparte and Novas 1985
Creators: name: Rauhut, Oliver W. M.
Publisher: name: Zenodo
Year: 2003
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Dinosauria
Abelisauridae

description: Abelisauridae Bonaparte and Novas, 1985 <i>Included taxa. Abelisaurus comahuensis Bonaparte and Novas, 1985</i>; <i>Camotaurus sastrei</i> Bonaparte, 1985; <i>Genusaurus sisteronis</i> Accarie, Beaudoin, Dejax, Friès, Michard and Taquet, 1995; <i>Ilokelesia aguadagrandensis</i> Coria and Salgado, 2000; <i>Indosuchus raptorius</i> Huene, 1932; <i>Majungatholus atopus</i> Sues and Taquet, 1979; <i>Masiakasaurus knopfleri</i> Sampson, Carrano and Forster, 2001; <i>Noasaurus leali</i> Bonaparte and Powell, 1980; <i>Xenotarsosaurus bonapartei</i> Martinez, Giménez, Rodriguez and Bochatey, 1986 <i>Temporal range.</i> Albian-Maastrichtian. <i>Occurrence.</i> Allen Formation, Rio Negro, Argentina; La Colonia Formation, Chubut, Argentina; unnamed unit (green clays and glauconitic sands of Bevons), Alpes de Haute-Provence, France; Lameta Formation, Madhya Pradesh, India; Maevarano Formation, Majunga, Madagascar; Lecho Formation, Salta, Argentina; Bajo-Barreal Formation, Chubut, Argentina. <i>Diagnosis.</i> Maxilla in front of the antorbital opening very short and high; posterior border of lacrimal convex over its entire length; anterior process of lacrimal reduced; jugal process of postorbital expanded, strongly anteriorly directed and intrudes into the orbit (convergently present in <i>Tarbosaurus bataar</i> and <i>Tyrannosaurus rex,</i> but not in other tyrannosaurids); epipophyses in the cervical vertebrae hypertrophied and higher than the neural spines. <i>Remarks.</i> Abelisaurids have recently been recognized as a distinct family of theropod dinosaurs (Bonaparte and Novas 1985). Their diagnosis and taxonomy is still problematic, mainly due to the fragmentary nature of the remains of all members of the family with the exception of <i>Camotaurus</i> (Bonaparte <i>et al.</i> 1990) and recently described new specimens of <i>Majungatholus</i> (Sampson <i>et al.</i> 1998). Given the many peculiarities in the skeleton of these genera, it seems very probable that the discovery of more complete material of other taxa will provide more diagnostic characters for this family. <i>Camotaurus sastrei</i> (Text-fig. 6a), <i>Majungatholus atopus,</i> and <i>Abelisaurus comahuensis</i> share all of the cranial synapomorphies listed above, and so their referral to the Abelisauridae is well supported. However, many other, very incompletely known taxa have been assigned to this family (Martinez <i>et al.</i> 1986; Bonaparte <i>et al.</i> 1990; Molnar 1990; Bonaparte 1991 <i>b</i>; Le Loeuff and Buffetaut 1991), and many of these assignments are problematical. Therefore, a short review of poorly known taxa that are included in the Abelisauridae here is given below. <i>Noasaurus leali</i> was originally assigned to its own family, Noasauridae (Bonaparte and Powell 1980). Later, Bonaparte (1991 /?) noted the close similarities between <i>Noasaurus</i> and abelisaurids and created the superfamily Abelisauroidea to include these two families (Bonaparte 1991 /?, p. 22). <i>Noasaurus</i> shares the first diagnostic character with <i>Abelisaurus, Carnotaurus,</i> and <i>Majungatholus,</i> and the fifth character with <i>Carnotaurus</i> and <i>Majungatholus,</i> and may therefore be regarded as a close relative of these taxa. Since the differences between the Noasauridae and Abelisauridae, as defined by Bonaparte (1991 /?), are only slight and may partly reflect size-dependant and/or ontogenetic differences, the recognition of two families is not accepted here. Although Coria and Salgado (2000) presented a cladogram of neoceratosaurs supporting the distinction of noasaurids and abelisaurids, their results must be seen as preliminary since only some taxa of the Abelisauria were included, characters were restricted to synapomorphies defining each node, and the majority of abelisaurid taxa considered in this analysis are known from less than 20 per cent of the skeleton. A more inclusive analysis might yield quite different results; therefore, all abelisaurs known are included in a single clade, Abelisauridae, here. However, apart from <i>Noasaurus,</i> the recently described <i>Masiakasaurus</i> also indicates an important diversity of small abelisaurids (Sampson <i>et al.</i> 2001). Although based on very fragmentary material, <i>Ilokelesia aguadagrandensis</i> can be demonstrated to be an abelisaur with some certainty, since it shares the pecularities of the postorbital and the hypertrophied cervical epipophyses with other abelisaurid taxa (Coria and Salgado 2000). <i>Indosuchus raptorius</i> was described by Huene (1932) and Huene and Matley (1933) on the basis of a posterior end of a skull roof from the Maastrichtian Lameta Formation of India, and more material was later referred to this taxon (Chatterjee 1978; Chatterjee and Rudra 1996). Sometimes considered to be a tyrannosaurid (Chatterjee 1978; Paul 1988 <i>«</i>), <i>Indosuchus</i> has recently been placed in the Abelisauridae by several authors (Bonaparte and Novas 1985; Buffetaut <i>et al.</i> 1988; Bonaparte <i>et al.</i> 1990; Bonaparte 1991 /?). Since there seem to be several large theropods in the Lameta Formation, the material referred to <i>Indosuchus</i> by Chatterjee (1978) cannot be shown to represent this taxon with certainty (Molnar 1990). However, the type specimen shows the same arrangement of the supratemporal fenestrae as found in <i>Abelisaurus, Majungatholus,</i> and <i>Carnotaurus;</i> thus, this species is referred to the Abelisauridae. <i>Genusaurus sisteronis</i> was described as a ceratosaurian theropod by Accarie <i>et al.</i> (1995) on the basis of several vertebrae and an incomplete pelvis and hindlimb. <i>Genusaurus</i> clearly represents a valid taxon, based on the peculiar morphology of the anterior end of the ilium (Accarie <i>et al.</i> 1995, fig. 4a; the anterior end of this element seems to be lacking only minor parts, and its overall morphology is real, not a result of preservation; Carrano, pers. comm. 1999). Although none of the diagnostic characters of the abelisaurids is evident from the published illustrations, <i>Genusaurus</i> is referred here to this clade, since it shares two apomorphic characters with <i>Carnotaurus:</i> the almost completely straight dorsal margin of the ilium, and the very long and vertically oriented ischial peduncle of the ilium. These characters are not present in an ilium of <i>Majungatholus</i> (UA 8678; Sampson <i>et al.</i> 1998, fig. 2f), indicating that, within abelisaurids, <i>Genusaurus</i> may be more closely related to <i>Carnotaurus</i> than to <i>Majungatholus.</i> <i>Xenotarsosaurus</i> is based on a dorsal vertebra and hindlimb elements, including femur, tibia, fibula, and astragalocalcaneum, from the Upper Cretaceous of Argentina (Martinez <i>et al.</i> 1986). Although none of the diagnostic characters of the family as diagnosed here is found in the holotype, the taxon is tentatively referred to the Abelisauridae, based on the great overall similarity of the preserved elements to the comparable elements of <i>Carnotaurus.</i> The recently described supposed abelisaurid <i>Tarascosaurus salluvicus</i> Le Loeuff and Buffetaut, 1991, from the Upper Cretaceous of southern France, is based on extremely fragmentary material that does not show any diagnostic characters and is, therefore, regarded as a <i>nomen dubium.</i> However, the presence of abelisaurids in the Upper Cretaceous of southern Europe is also supported by other material (Buffetaut <i>et al.</i> 1988).
description: Published as part of <i>Rauhut, Oliver W. M., 2003, The interrelationships and evolution of basal theropod dinosaurs, pp. 1-213 in Special papers in palaeontology 69</i> on pages 33-34, DOI: 10.5281/zenodo.3382576
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