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Muyelensaurus pecheni gen. et sp.nov., preserved bones (in black) shown in a titanosaur skeletal reconstruction of LEHMAN & COULSON (2002).
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The discovery of Muyelensaurus pecheni gen. et sp.nov., a new slender titanosaurid, is relevant from anatomical and systematic viewpoints. The specimens come from the Upper Cretaceous strata of the Portezuelo Formation (Turonian-Early Coniacian) at Loma del Lindero, Rincón de los Sauces area, Neuquén Province, Argentina. The remains include a brain...
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Context 1
... sternal plate (MRS-Pv 125) exhibits a typical semilunar contour, and its posterior border is not straight as that present in some titanosaurs, like Mendozasaurus and Malawisaurus (GONZÁLEZ RIGA, 2003). A complete right scapula ( Fig.12.A; MRS-Pv 259) and two partial scapular blades (MRS-Pv 396 and 397) were recovered. ...
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Argentinosaurus (Cenomanian, Argentina) is generally accepted as being the largest dinosaur so far discovered and is one of several giant titanosaurian sauropods known from the Upper Cretaceous of South America and Asia, but surprisingly not from North America. Here we present the first evidence of giant titanosaurian sauropods from the Upper Creta...
Citations
... The confirmed record of non-avialan maniraptorans from the Neuquén Basin comes from the Candeleros (Cenomanian; Makovicky et al. 2005Makovicky et al. , 2012, Huincul (Motta et al. 2020), Portezuelo (Turonian-Coniacian;Novas 1996;Novas and Puerta 1997;Calvo et al. 2004;Novas and Pol 2005;Porfiri et al. 2011), Bajo de la Carpa (Santonian; Bonaparte 1991; Martinelli and Vera 2007;Porfiri et al. 2024), and Allen (middle Campanian-lower Maastrichtian; Novas et al. 2009;Agnolín et al. 2012;Currie and Paulina Carabajal 2012) formations. The Plottier Formation (late Coniacian-early Santonian; Garrido 2010), unlike the other mentioned geological units, has a scarcer dinosaur record, primarily consisting of sauropods (von Huene 1929;Calvo et al. 2007;Filippi et al. 2011Filippi et al. , 2013González Riga et al. 2016;Bellardini et al. 2018), although ornithopods are also present (Cruzado-Caballero et al. 2016). Regarding theropod remains from this formation, they are rare and limited to a large-sized coelurosaur (Coria et al. 2001;Coria and Currie 2002), and isolated teeth assigned to abelisaurids, unenlagiines, and indeterminate coelurosaurs, including Maniraptora indet Salgado et al. 2009;Meso et al. 2021). ...
A new specimen, MAU-Pv-PH-453, comprising an isolated femur from the Plottier Formation (Coniacian-Santonian), northern Patagonia, is described here. Its characteristics, i.e., an anteriorly curved diaphysis; fused lesser and greater trochanters forming a trochanteric crest; a prominent medially directed head; and the absence of a fourth trochanter, allow us to identify it as belonging to a maniraptoran theropod. Among Patagonian maniraptorans, MAU-Pv-PH-453 shares similarities with alvarezsaurians, such as the absence of a posterior trochanter, a trochanteric shelf, and the fourth trochanter. However, in Patagonian alvarezsaurs, the lesser and greater trochanters are generally separated by a cleft. Notably, MAU-Pv-PH-453 exhibits some features seen in femora of parvicursorine alvarezsaurids, including a proximally projected trochanteric crest and an L-shaped profile in proximal view. However, MAU-Pv-PH-453 presents differences with parvicursorines, such as a knob partially separating the lesser and greater trochanters. Phylogenetically, MAU-Pv-PH-453 may have parvicursorine affinities, although its fragmentary nature might generate a bias in its phylogenetic position. Due to the lack of more diagnostic characters, MAU-Pv-PH-453 is assigned to Alvarezsauria indet. This material represents the second theropod record from the Plottier Formation and it could fill a temporal gap (between Coniacian and Santonian) in the record of Upper Cretaceous Patagonian alvarezsaurians.
... Among the findings of theropod dinosaurs are the eponymous megaraptorid Megaraptor namunhuaiquii [2], the alvarezsaurid Patagonykus puertai [3,4], the unenlagiine dromaeosaurids Unenlagia comahuensis [5], Unenlagia paynemili [6], Neuquenraptor argentinus [7], and Pamparaptor micros [8], an unnamed early-diverging basal abelisauroid [9], the abelisaurid Elemgasem nubilus [10], and neornithine birds [11]. As for the sauropod dinosaurs, two taxa have been formally described, the titanosaur Futalongkosaurus dukei [12], and Muyelensaurus pecheni [13]. In the Mendoza province, [14] recorded Malarguesaurus florenciae in the Portezuelo Formation. ...
The study of thirty-two shed crowns from the Portezuelo Formation (middle Turonian-late Coniacian) at the Sierra del Portezuelo locality, reveals six distinct tooth morphotypes identified through cladistic, discriminant, and cluster analyses. Two morphotypes were identified as belonging to Megaraptoridae, three to Abelisauridae, one to Abelisauroidea, and one to Alvarezsauridae. Additionally, two of the morphotypes exhibit a combination of dental features typically found in megaraptorid and abelisauridtheropods. These results suggest a greater diversity of theropods in the original ecosystem than previously thought, including the presence of a second morphotype of megaraptorid and alvarezsaurid previously undocumented in this formation. Furthermore, the existence of Morphotype 6 indicates the potential coexistence of medium-sized abelisauroids alongside larger abelisaurids in the same ecosystem. These findings underscore the importance of future expeditions to the Sierra del Portezuelo locality to further our understanding of these previously unknown theropod species.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12862-024-02249-8.
... [111] from Late Cretaceous of Mongolia, Asia, while in contrast Jainosaurus Bara Simla braincase (GSI K27/497; [93], fig. 5) and Bara Simla Jabalpur braincase ISI R162 [107] from latest Cretaceous of India, Vahiny Depereti [112] from Late Cretaceous of Madagascar, Malawisaurus [105] from Malawi, Africa, Saltasaurus PVL 4017 [103], Muyelensaurus [113] and Puekunsaurus [114], Kaijutitan maui [115] from Argentina, South America, Quaesitosaurus [116] from Late Cretaceous of Mongolia, Asia and Phuwiangosaurus sirindhornai [117] from early Cretaceous of Thailand, Asia show occipital condyle parallel to skull roof. ...
... It has large osteodermal ellipsoid without median cut 13) Sulaimanisaurus gingerichi [68] vide [88] Its holotypic and referred specimens, type and referred localities, horizon and age along with year of informal and formal description and basinal distribution were mentioned in (Table 11). Its diagnosis and descriptions of caudals are also shown in ( [70], pages [112][113]. Its four caudals found positioned in anterior (known by well developed transverse process0, while other 3 belong to mid caudal series. ...
... Among the ndings of theropod dinosaurs are the eponymous megaraptoridMegaraptornamunhuaiquii [2], the alvarezsauridPatagonykuspuertai [3,4], the unenlagiinedromaeosauridsUnenlagiacomahuensis [5], Unenlagiapaynemili[6], Neuquenraptorargentinus [7], and Pamparaptor micros [8],an unnamed earlydiverging basal abelisauroid [9], the abelisauridElemgasemnubilus [10], and neornithine birds [11]. As for the sauropod dinosaurs, two taxa have been formally described, the titanosaurFutalongkosaurusdukei [12], andMuyelensauruspecheni [13]. In the Mendoza province, [14] recorded Malarguesaurus orenciae in the Portezuelo Formation. ...
The study of thirty-two shed crowns from the Portezuelo Formation (middle Turonian-late Coniacian) at the Sierra del Portezuelo locality, reveals six distinct tooth morphotypes identified through cladistic, discriminant, and cluster analyses. Two morphotypes were identified as belonging to Megaraptoridae, three to Abelisauridae, one to Abelisauroidea, and one to Alvarezsauridae. Additionally, two of the morphotypes exhibit a combination of dental features typically found in megaraptorid and abelisauridtheropods. These results suggest a greater diversity of theropods in the original ecosystem than previously thought, including the presence of a second morphotype of megaraptorid and alvarezsaurid previously undocumented in this formation. Furthermore, the existence of Morphotype 6 indicates the potential coexistence of medium-sized abelisauroids alongside larger abelisaurids in the same ecosystem. These findings underscore the importance of future expeditions to the Sierra del Portezuelo locality to further our understanding of these previously unknown theropod species.
... In our analysis, the Clade A is composed of a subclade integrated by two branches, one containing Bonitasaura as the sister taxon of Inawentu plus Antarctosaurus. The second includes Narambuenatitan and a series of derived taxa, as the other squared-jaw Brasilotitan and several forms which have an unknown snout shape, such as Uberabatitan (Salgado & De Souza Carvalho, 2008), Muyelensaurus (Calvo et al., 2007b), Rinconsaurus (Calvo & Gonz alez Riga, 2003), Overosaurus, Trigonosaurus, and Arrudatitan (Silva Junior et al., 2021) (Fig. 6). Inawentu includes some anatomical traits shared with both Antarctosaurus and Bonitasaura. ...
A new titanosaur sauropod genus including an almost complete skull and axial elements to the hips, reflecting a convergent bauplan with the older rebbachisaurids sauropods.
... The measured vertebra of Chondrosteosaurus was identified only as presacral (Taylor & Wedel, 2013). The phylogeny presented here is for illustrative purposes only and is based on various analyses (e.g., Calvo et al., 2007a;Coria et al., 2019;D'Emic, 2012;Martínez et al., 2016;Whitlock, 2011;Wilson, 2002). Abbreviations: ASP, airspace proportion; Ca, caudal vertebrae; Cv, cervical vertebrae; Dr, dorsal ribs; Dv, dorsal vertebrae; I, ilium. ...
Many sauropod dinosaurs exhibit extensive postcranial skeletal pneumaticity that may have facilitated the
evolution of extreme body sizes. Among titanosauriforms, complex, irregularly branching camellate chambers are found
throughout the presacral vertebral column, often invading the ribs and ilium as well. To explore the function of these
camellae, including reduction in bone volume, pneumaticity was examined in a titanosaur sauropod from the Upper
Cretaceous Black Peaks Formation of Big Bend National Park, Texas, that includes pneumatic dorsal ribs and ilia. Using
natural breaks to non-destructively observe the internal structure, patterns of camellate pneumaticity are described for the
dorsal vertebrae, ribs, and ilium. The space occupied by camellae is quantified as the airspace proportion, which is
reported here in a sauropod ilium for the first time. Airspace proportions exceed 70% in parts of the dorsal vertebrae and
ilium, with lower values near the cotyles of the vertebral centra and the acetabulum. Values in the ribs decrease distally.
These values are not appreciably different from those of sauropods with simpler camerate pneumaticity. If camellae did
not offer greater weight reduction than camerae, they may have enhanced structural strength, as the chambers appear to
align with stress in the vertebral centra and ilium. Apneumatic trabecular bone around the acetabulum, preacetabular
process, and postzygapophyses, however, may indicate stresses too great for camellate bone to bear, although an
ontogenetic influence cannot be ruled out.
... In lateral view, the premaxilla-maxilla contact is essentially straight, as in non- [111][112][113][114], and some titanosaurs (e.g. Malawisaurus [115], Muyelensaurus pecheni [116], Tapuiasaurus [21,22]); this distinguishes Diamantinasaurus from brachiosaurids and Nemegtosaurus, in which this contact is sinuous [20,26]. Lateral to the tooth row, there is a prominent plate of bone, as in sauropods generally [106,117]. ...
Titanosaurian sauropod dinosaurs were diverse and abundant throughout the Cretaceous, with a global distribution. However, few titanosaurian taxa are represented by multiple skeletons, let alone skulls. Diamantinasaurus matildae, from the lower Upper Cretaceous Winton Formation of Queensland, Australia, was heretofore represented by three specimens, including one that preserves a braincase and several other cranial elements. Herein, we describe a fourth specimen of Diamantinasaurus matildae that preserves a more complete skull—including numerous cranial elements not previously known for this taxon—as well as a partial postcranial skeleton. The skull of Diamantinasaurus matildae shows many similarities to that of the coeval Sarmientosaurus musacchioi from Argentina (e.g. quadratojugal with posterior tongue-like process; braincase with more than one ossified exit for cranial nerve V; compressed-cone–chisel-like teeth), providing further support for the inclusion of both taxa within the clade Diamantinasauria. The replacement teeth within the premaxilla of the new specimen are morphologically congruent with teeth previously attributed to Diamantinasaurus matildae, and Diamantinasauria more broadly, corroborating those referrals. Plesiomorphic characters of the new specimen include a sacrum comprising five vertebrae (also newly demonstrated in the holotype of Diamantinasaurus matildae), rather than the six or more that typify other titanosaurs. However, we demonstrate that there have been a number of independent acquisitions of a six-vertebrae sacrum among Somphospondyli and/or that there have been numerous reversals to a five-vertebrae sacrum, suggesting that sacral count is relatively plastic. Other newly identified plesiomorphic features include: the overall skull shape, which is more similar to brachiosaurids than ‘derived' titanosaurs; anterior caudal centra that are amphicoelous, rather than procoelous; and a pedal phalangeal formula estimated as 2-2-3-2-0. These features are consistent with either an early-branching position within Titanosauria, or a position just outside the titanosaurian radiation, for Diamantinasauria, as indicated by alternative character weighting approaches applied in our phylogenetic analyses, and help to shed light on the early assembly of titanosaurian anatomy that has until now been obscured by a poor fossil record.
... These structures become less developed, shallower, and not limited by a sharp-lipped edge throughout the anterior series of the caudal vertebrae, but they are sometimes still visible in the remaining anterior caudal vertebrae [see caudal vertebra VI of Mendozasaurus neguyelap (González Riga et al. 2018). The presence of pocdf in the anterior caudal vertebrae have been identified in several other titanosaurs such as Abdarainurus barsboldi (Averianov and Lopatin, 2020), Alamosaurus sanjuanensis (Gilmore 1946), Bonitasaura salgadoi (Gallina and Apesteguía, 2015), Dongyungosuurus sinensis (Lü et al. 2008), Epachthosaurus sciuttoi (Mannion et al. 2019b), Futalognkosaurus dukei (Mannion et al. 2019b), Malawisaurus dixeyi (Gomani 1999(Gomani , 2005, Muyelensaurus pecheni (Calvo et al. 2007a), Normanniasaurus genceyi (Le Loeuff et al. 2013;pers. observ. ...
The Upper Cretaceous sauropod record from Romania is abundant, but mainly composed by isolated and poorly preserved specimens. They were found in Maastrichtian units cropping out in both the western-southwestern margin of the Transylvanian Basin, and in the Hațeg and Rusca Montană basins. Two small-sized taxa, Magyorasaurus dacus and Paludititan nalatzensis, were considered as valid; however, the presence of other forms is not ruled out. An important sample of sauropod caudal vertebrae is described in detailed to provide new data about the diversity of the sauropods of the Hațeg Island during the Maastrichtian. Distinct morphologies are recognized for the caudal vertebrae, including four morphologies for the anterior-most elements; at least three for the anterior and middle ones, and at least two for the posterior caudals, including sauropods with opisthocoelous condition. The possibility of four different tail morphologies is suggested, which might belong to four different taxa, including Paludititan nalatzensis, Magyarosaurus dacus (the material previously referred to it seems to be composed by more than one taxon) and two other species. A new character for morphological datasets describing the position of the intraprezygapophyseal lamina in the middle and posterior caudals is proposed, which may be characteristic of some European taxa.
... As in LPP-PV-0206, the PRSL of MPMA 08-0060/07 is almost absent, and the neural spine is low and strongly posterodorsally projected, bearing a ventrally broad POSL filling the posterior surface. The postzygapophyses are flat, with an outline that tapers posterodorsally, lacking postzygapophyseal bony processes and laterally developed hyposphenal ridges laterally developed present in rinconsaurians and Epachthosaurus sciuttoi (Martínez et al., 2004;Calvo et al., 2007). ...
... as Mansourasaurus as the sister group of Lirainosaurinae (Sallam et al., 2018) and aeolosaurines more closely related to Rinconsauria than saltasaurines (Calvo et al., 2007). ...
Titanosaurian sauropods are known to exhibit remarkable body size disparity, with some taxa famed for nearing the zenith of terrestrial vertebrate body size. Here, we describe a new titanosaurian – Ibirania parva gen. et sp. nov. – from the Upper Cretaceous (Santonian–
Campanian) São José do Rio Preto Formation of Bauru Basin, in which represents one of the smallest sauropods known to date. The new taxon is diagnosed by seven autapomorphies and had an estimated body length of 5.7 m. Histological and μCT scan analyses showed that this new taxon is represented by skeletally mature individuals, which had attained somatic maturity prior to death. Phylogenetic analyses recovered the new taxon deeply nested within Saltasaurinae, a clade previously known by small-sized forms. Ibirania parva gen. et sp. nov. brings new information indicating that the body size reduction in some titanosaurians could be driven by recurrent ecophysiographical settings, present in South America prior to the diversity peak attained by the group during the Campanian–Maastrichtian.
... Mendozasaurus neguyelap was discovered in the middle-upper Coniacian Sierra Barrosa Formation, in Mendoza Province (González Riga , 2005. The anatomy of this taxon has been extensively studied (González , helping to define two new titanosaurian clades: Lognkosauria (Calvo et al. 2007a) and Colossosauria (González . Approximately 200 bones and bone fragments, which represent four individuals, were recovered from the Arroyo Seco site. ...
Most taphonomy studies of South American sauropodomorphs have addressed extrinsic factors such as sedimentary environments, bone dispersal, and mineralogical processes that occurred during fossil diagenesis. These studies provide important data on the taphonomic modes which are associated with bone accumulations in different paleoenvironmental contexts. However, these analyses have generally not considered intrinsic factors like the shape, size, and structural integrity of the skeletal elements, variables that can produce some taphonomic bias. Sauropodomorphs include dinosaurs of highly varied sizes, ranging from small (less than 8 m long) to remarkably giant forms (around 30 m long). In the largest sauropods, such as the huge titanosaurs, very incomplete skeletons are commonly found and most notably skull and articulated pedes rarely are preserved. We focus here on some intrinsic anatomical factors as they relate to articulation in some key parts of the skeletons. Further, this study suggests that the preservation of fragile portions of sauropodomorph skeletons was possible only under specific combinations of sedimentological and biological processes.
