Figure 1 – Recent discoveries of appendicular skeletal elements of Late Cretaceous titanosaurian sauropods from the Neuquén Basin of southern Argentina. (a) complete and articulated left hind limb of the unnamed La Invernada taxon (MUCPv-1533), (b) complete and articulated distal left hind limb of the unnamed Agua del Padrillo taxon (UNCUYO-LD 313), (c) right humerus of Notocolossus gonzalezparejasi (UNCUYO-LD 301), (d) complete and articulated right pes of Notocolossus gonzalezparejasi (UNCUYO-LD 302). Scale bar equals 10 cm in (d).

An overview of the appendicular skeletal anatomy of South American titanosaurian sauropods, with definition of a newly recognized clade

BERNARDO J. GONZÁLEZ RIGA 1, MATTHEW C. LAMANNA 2, ALEJANDRO OTERO 3,

LEONARDO D. ORTIZ DAVID 1, ALEXANDER W.A. KELLNER 4 and LUCIO M. IBIRICU 5

1 CONICET/Laboratorio y Museo de Dinosaurios, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Padre Contreras 1300, Parque Gral. San Martin, Mendoza Capital 5500, Mendoza, Argentina

2 Section of Vertebrate Paleontology, Carnegie Museum of Natural History, 4400

Forbes Avenue, Pittsburgh, Pennsylvania 15213, U.S.A.

3 CONICET, División Paleontología de Vertebrados, Museo de La Plata, Paseo del Bosque, s/n, La Plata, B1900FWA, Argentina

4 Laboratório de Systemática e Tafonomia de Vertebrados Fósseis, Departamento de Geologia e Paleontologia, Museu Nacional,

Universidade Federal do Rio de Janeiro, Quinta da Boa Vista, São Cristóvão, 20940-040 Rio de Janeiro, RJ, Brazil

5 Instituto Patagónico de Geología y Paleontología (IPGP–CONICET), Boulevard

Almirante Brown, 2915, Puerto Madryn, 9120, Chubut, Argentina

How to cite: GONZÁLEZ RIGA BJ, LAMANNA MC, OTERO A, ORTIZ DAVID LD, KELLNER AWA AND IBIRICU LM. 2019. An overview of the appendicular skeletal anatomy of South American titanosaurian sauropods, with definition of a newly recognized clade. An Acad Bras Cienc 91:e20180374. DOI 10.1590/0001-3765201920180374. 

You can see the paper in PDF format free: (19) (PDF) An overview of the appendicular skeletal anatomy of South American titanosaurian sauropods, with definition of a newly recognized clade (researchgate.net)

Abstract: In the last two decades, the number of phylogenetically informative anatomical characters recognized in the appendicular skeleton of titanosaurian sauropod dinosaurs has increased dramatically with the discovery of new and comparatively complete specimens. Here we provide an overview of the appendicular skeletal morphology of South American titanosaurs and discuss its significance for phylogenetic reconstruction. The appendicular skeletal diversity of South American titanosaurs is substantially greater than was initially appreciated. Moreover, some regions of the appendicular skeleton, such as the pes, exhibit remarkable variability in form. Multiple synapomorphies of Titanosauria and the less inclusive clades Lithostrotia and Saltasauridae consist of characters of the girdles and limbs. Although the phylogenetic definitions of titanosaurian clades such as Saltasaurinae and Lognkosauria are stable, the taxonomic content of these clades has varied in recent analyses depending on the phylogenetic topology recovered. Within Titanosauria, the results of four recent, largely independent analyses support the existence of a derived titanosaurian lineage distinct from the ‘Saltasaurinae line,’ which is herein termed Colossosauria. At present, this clade is mainly comprised by taxa within Lognkosauria and Rinconsauria, and is useful in discussions of titanosaurian lower-level relationships. Key words: Titanosauria, South America, appendicular skeleton, osteology, phylogeny, Colossosauria.

Figure 4 – Morphological and size comparison of titanosaurian right humeri in anterior view. South American (Argentinean) taxa marked with an asterisk. (a) Neuquensaurus australis* (left, reversed), redrawn from Otero (2010), (b) Rapetosaurus krausei (left, reversed), redrawn from Curry Rogers (2009), (c) Muyelensaurus pecheni* (left, reversed), redrawn from Calvo et al. (2007c), (d) Narambuenatitan palomoi* (left, reversed), redrawn from Filippi et al. (2011a), (e) Mendozasaurus neguyelap*, redrawn from González Riga et al. (2018), (f) Angolatitan adamastor, redrawn from Mateus et al. (2011), (g) Dreadnoughtus schrani* (left, reversed), redrawn from Lacovara et al. (2014), (h) Patagotitan mayorum* (left, reversed), redrawn from Carballido et al. (2017), (i) Paralititan stromeri, redrawn from Smith et al. (2001), (j) Notocolossus gonzalezparejasi*, redrawn from González Riga et al. (2016). Scale bar equals 20 cm.

Figure 9 – The best-preserved pedes of titanosaurian sauropods. South American (Argentinean) taxa marked with an asterisk. (a) Opisthocoelicaudia skarzynskii, ZPAL MgD-I/48, right pes, redrawn from Borsuk-Bialynicka (1977), (b) Epachthosaurus sciuttoi*, UNPSJB-PV 920, right pes, redrawn from Martínez et al. (2004), (c) La Invernada taxon*, MUCPv-1533, left pes, redrawn from González Riga et al. (2008a), (d) Agua del Padrillo taxon*, UNCUYO-LD 313, left pes, redrawn from González Riga et al. (2015), (e) ?Alamosaurus sanjuanensis, NMMNH P-49967, right pes, redrawn from D’Emic et al. (2011), (f) Mendozasaurus neguyelap*, IANIGLA-PV 077/1–10, 078/1–2, 079, right pes, redrawn from González Riga et al. (2018), (G) Notocolossus gonzalezparejasi*, UNCUYO-LD 302, right pes, redrawn from González Riga et al. (2016). Scale bars equal 10 cm.

An overview of the appendicular skeletal morphology of titanosaurian taxa from South America indicates that this part of the skeleton exhibits greater anatomical diversity than was initially appreciated. Detailed comparative studies of each of these appendicular elements and skeletal regions would likely yield additional character information useful for phylogenetic analyses. From a systematic point of view, the present review shows that there is no definitive consensus on the appendicular character states that serve as synapomorphies for Titanosauria and Lithostrotia. However, within Titanosauria, recent phylogenetic analyses confirm the presence of a titanosaurian lineage that differs from the ‘Saltasaurinae line.’Four recent cladistic studies based on largely independent datasets have recovered this new clade, which is herein termed Colossosauria. At present, this clade is mainly comprised by taxa belonging to Rinconsauria and Lognkosauria, the latter including several exceptionally gigantic species.

Figure 11 – Strict consensus cladogram (limited to Titanosauria) generated from a revised analysis of the data matrix of González Riga et al. (2018) with the addition of three characters (this paper), showing the position and taxonomic content of the newlyrecognized stem-based clade Colossosauria. Abbreviations: Lo, Lognkosauria, Ri, Rinconsauria, Sa, Saltasauridae.

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