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New titanosauriform (Sauropoda) from the Poison Strip Member of Cedar Mountain Formation (Lower Cretaceous), Utah

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... In lateral view, the proximal articular surface is slightly convex (Figure 15E), as in Limaysaurus and Sauroposeidon (Calvo and Salgado 1995;Rose 2007), unlike the condition present in several Titanosauriformes where this surface is strongly posteriorly inclined (e.g. Antarctosaurus, Epachthosaurus, Gobititan, Venenosaurus, and Notocolossus;von Huene 1929;Tidwell et al. 2001;You et al. 2003;Martínez et al. 2004;González Riga et al. 2016). ...
... On the other hand, in Agustinia, the anterior and posterior surfaces of metatarsal I are straight and sub-parallel in lateral view, at least up to half of the bone, a unique condition within Sauropoda ( Figure 4S). In Tazoudasaurus the anterior and posterior surfaces are straight in lateral view but only in the proximal third of the metatarsal I ( Figure 4U), whereas in Venenosaurus only the anterior edge is straight in lateral view up to half of the bone (Fig. 4AC) (Tidwell et al. 2001;Allain et al. 2004;Allain and Aquesbi 2008;Peyer and Allain 2010). Conversely, the metatarsal I of the rebbachisaurid Lavocatisaurus MAU-PV-1232/81 ( Figure 4A) shows a laminar and prominent posterior surface that strongly resembles the condition seen in Agustinia, although the anterior surface is shallow and concave in lateral view. ...
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The Lohan Cura Formation (Albian) at the Cerro de los Leones locality (Neuquén Province, Patagonia, Argentina) yielded several fossil materials, especially sauropod specimens. Among these, Agustinia ligabuei includes postcranial elements of a single individual, with widely debated taxonomy and phylogeny. Here, we provide an extended osteological description and illustrations of the axial and appendicular elements of Agustinia, as well as a revised diagnosis. Moreover, the phylogenetic analysis including a new combination of morphological features recognises Agustinia as a basal Rebbachisauridae, closely related with other South American rebbachisaurids. Our results suggest a more diversified sauropod fauna in the Neuquén Basin, where different members of both neosauropod lineages (i.e. Macronaria and Diplodocoidea) survived in the same region during the Albian age. The reassessment of Agustinia as a basal rebbachisaurid improves our knowledge about the early stages of evolutionary history of Rebbachisauridae, adding new information on the morphological and taxonomic diversification of the clade during the Early Cretaceous of southwestern Gondwana.
... Otherwise, Berriasian-Valanginian sauropod faunas in North America are dominated by turiasaurians [253,254], a group for which there is currently no Jurassic-or post-Valanginian-record in North America. Barremian-lower Aptian deposits in Utah have produced the brachiosaurid Venenosaurus [255] and indeterminate titanosauriforms [256,257], and lower Aptian deposits in Maryland have produced abundant evidence of titanosauriforms [258][259][260][261][262][263]. The nontitanosaurian somphospondylan Sauroposeidon (=Paluxysaurus) spans the Aptian-Albian of Texas and Oklahoma [221,[264][265][266][267][268], and possibly Arkansas [269]; other titanosauriforms recorded from this interval include indeterminate forms from Nevada, Montana and Wyoming [270][271][272][273][274], the brachiosaurid Abydosaurus [2] and the somphospondylan Brontomerus [64,275] from Utah, and a brachiosaurid possibly referable to Cedarosaurus [276][277][278], the somphospondylan Astrophocaudia [276,278] and indeterminate forms [276] from Texas. ...
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The Upper Cretaceous Winton Formation of Queensland, Australia, has produced several partial sauropod skeletons, but cranial remains—including teeth—remain rare. Herein, we present the first description of sauropod teeth from this formation, based on specimens from three separate sites. An isolated tooth and a dentary fragment from the Diamantinasaurus matildae type locality are considered to be referable to that titanosaurian taxon. A single tooth from the D. matildae referred specimen site is similarly regarded as being part of that individual. Seventeen teeth from a new site that are morphologically uniform, and similar to the teeth from the two Diamantinasaurus sites, are assigned to Diamantinasauria. All sauropod teeth recovered from the Winton Formation to date are compressed-cone-chisel-shaped, have low slenderness index values (2.00–2.88), are lingually curved at their apices, mesiodistally convex on their lingual surfaces, and lack prominent carinae and denticles. They are markedly different from the chisel-like teeth of derived titanosaurs, more closely resembling the teeth of early branching members of the titanosauriform radiation. This provides further support for a ‘basal’ titanosaurian position for Diamantinasauria. Scanning electron microscope microwear analysis of the wear facets of several teeth reveals more scratches than pits, implying that diamantinasaurians were mid-height (1–10 m) feeders. With a view to assessing the spatio-temporal distribution of sauropod tooth morphotypes before and after deposition of the Winton Formation, we provide a comprehensive continent-by-continent review of the early titanosauriform global record (Early to early Late Cretaceous). This indicates that throughout the Early–early Late Cretaceous, sauropod faunas transitioned from being quite diverse at higher phylogenetic levels and encompassing a range of tooth morphologies at the start of the Berriasian, to faunas comprising solely titanosaurs with limited dental variability by the end-Turonian. Furthermore, this review highlights the different ways in which this transition unfolded on each continent, including the earliest records of titanosaurs with narrow-crowned teeth on each continent.
... Apatosaurus, Tehuelchesaurus, Tastavinsaurus, Phuwiangosaurus : Hatcher 1901;Martin et al. 1999;Canudo et al. 2008;Carballido et al. 2011b), but it has two different angled sections. The proximal quarter of the articular surface is posteriorly directed, whereas the other three-quarters face posterodorsally, with the opening of the obturator foramen marking the dividing line of these articular surfaces (Fig. 9E, F) Ostrom & McIntosh 1966;Tidwell et al. 2001). The ischiadic articular surface merges into the pubic symphysis through a laminar, non-articular plate of bone (Fig. 9A, B, E, F). ...
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The Late Jurassic was a period of great diversity for sauropod dinosaurs, with different lineages of Neosauropoda flourishing, including several camarasauromorph taxa. Efforts made in recent years have resulted in a great increase in our current knowledge of basal camarasauromorph evolution, including both the detailed description of new and previously poorly known sauropods and expanded phylogenetic analyses. Although most recent phylogenies converge in their results on early camarasauromorph diversification, the phylogenetic position of Europasaurus, from the Late Jurassic of Germany, remains controversial despite the completeness of the material representing this species. Although Europasaurus was recovered as a relatively basal camarasauromorph in all phylogenetic analyses to date, some of them retrieved this taxon in a slightly more derived position, among basal brachiosaurids. Europasaurus is not only one of the most complete camarasauromorphs but also the first unequivocal dwarf that evolved through paedomorphosis, retaining several plesiomorphic characters, especially in the cranium. Cranial and axial material of Europasaurus has been described in detail but the appendicular skeleton has not. The current paper rectifies this by providing detailed descriptions and illustrations of its appendicular skeleton. In addition, an extensive re-evaluation of the systematic position of Europasaurus was done based on the three most substantial data sets published in recent years. These analyses resolved Europasaurus as a basal camarasauromorph in all cases, but brachiosaurid affinities remain plausible, especially considering the heterochronic evolution of the taxon.
... Sauropod metacarpal bones are basically cylindrical, pipelike bones. In neosauropods like Apatosaurus louisae (Gilmore 1936 In the basal titanosaur Chubutisaurus, MPCA 11,051 and the brachiosaurid Venenosaurus (Tidwell et al. 2001) the proximal region is divided into two portions: a bulky posterior region, which commonly enter the central part of the metacarpus as a whole, and a thin and curved part provided by a concave facet for the metacarpal II, plus a convex surface to the medial side, resulting in a colonnade general aspect. ...
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The fossil-bearing Jagua Formation of western Cuba was deposited during the early Late Jurassic (middle to late Oxfordian) in the marine corridor developed between western Laurasia and Gondwana, providing a rich assemblage of terrestrial to marine fossils including reptiles, fish and invertebrates. From this formation, De la Torre y Callejas reported in 1949 an isolated dinosaur bone, now missing, originally identified as ‘Diplodocus’ or ‘Brontosaurus’ humerus. Later, this fossil was referred as a camarasauromorph metacarpal. Within Macronaria, metacarpals became long and robust in Titanosauriformes. The strong curvature of the Cuban metacarpus suggests that it probably belongs to the first or second metacarpal of a somphospondylan. The achievement of a eugraviportal forelimb in Sauropoda was a unique event evidenced in metacarpal morphology. The bowed first metacarpal is present only in somphospondylans, particularly in some basal titanosaurs, and reverses in derived forms. Somphospondylans were not recorded yet for the early Late Jurassic neither in North nor in South America.
... caudal vertebra, Fig. 8A1, 8A2e8A4) has the anterior surface of the centrum wider than high, with a circular outline (Fig. 8A1), which is similar to MP-285 (Franco-Rosas et al., 2004) Trigonosaurus and Baurutitan Kellner et al., 2005, as well differ from the same height and width of Gondwanatitan (Kellner and Azevedo, 1999) and MP-287 (Franco-Rosas et al., 2004). No signs of the lateral depression is presented, differing from Alamosaurus, Saltasaurus, Malawisaurus, Aeolosaurus rionegrinus, Gondwanatitan and the titanosauriform Venenosaurus (Tidwell et al., 2001) forming true fossae in the latter. The neural spine is extremely low, similar to what occurs to Aeolosaurus rionegrinus and Aeolosaurus colhuehuapensis (Fig. 8A2e8A4). ...
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Osteological knowledge of the sauropod dinosaur Ligabuesaurus leanzai is increased by the description of new postcranial elements assigned to the holotype MCF-PVPH-233. Furthermore, a newly referred specimen, MCF-PVPH-228, is recognized after a detailed revision of the abundant sauropod material collected from the Lohan Cura Formation outcrops in the Cerro de los Leones locality (southern Neuquén Basin, Patagonia, Argentina). Recent laboratory preparation and fieldwork allowed us to recognize several new morphological features of the pectoral and pelvic girdles and the cervical and caudal anatomy. Thus, a new diagnosis of Ligabuesaurus is proposed that includes new autapomorphies and a unique combination of features. A phylogenetic analysis based on this new material recovers Ligabuesaurus as a non-titanosaurian somphospondylan, more derived than Sauroposeidon. Therefore, we discuss the palaeobiogeographical implications for the diversification and distribution of South American somphospondylans, especially in the Neuquén Basin, which are closely related to the early stages of evolution of Titanosauria. In this context, Ligabuesaurus represents one of the more complete Early Cretaceous Titanosauriformes and the earliest non-titanosaurian somphospondylan of South America. Finally, the new information on Ligabuesaurus contributes not only to reconstruction of the sauropod faunal composition of south-western Gondwana, but also sheds light on the early stages and emergence of titanosaurians.
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Chubutisaurus insignis Del Corro (1975) from the Aptian Gorro Frigio Formation) of Chubut Province, Argentina, is a large sized dinosaur having controversial phylogenetic relationships within the Sauropoda. Orginally it was regarded as a member of a new family (Chubutisauridae) because of the amphiplatyan caudal vertebrae. Chubutisaurus insignis was then distinguished from the well-known and widely reported Late-Cretaceous titanosaurids, characterized by procoelous caudal vertebrae. Finally, it was suggested to include Chubutisaurus insignis within the Brachiosauridae because it shares several characters with Brachiosaurus and other members of the group. The holotype of Chubutisaurus insignis is here redescribed and interpreted. Probable affinities of this fossil are discussed adding information to the faunal characteristics of the mid-Cretaceous of Gondwana. -from Author
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