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The record of non-avian theropods from Patagonia is numerous and diverse. With new expeditions in unknown places these discoveries has been increased notably. Here, we present a new articulated postcranial skeleton belonging to a not previously reported theropod. These materials represent a theropod of medium size, possibly eight meters length. The new theropod was found in levels corresponding to the Bajo La Carpa Formation, Neuquén Group (Santonian-Late Cretaceous) of Patagonia, Argentina. The new locality is named Tratayén, placed at 22 km at southeastern to Añelo city, Neuquén, Argentina. The recovered materials (MUCPV-1162) comprise seven dorsal and five sacral vertebrae, proximal ribs, incomplete right ilium and incomplete right isquion? The neural arch in dorsal and sacral vertebrae presents tall neural spines compressed laterally with the rectangular distal end, and thin laminae below to diapophyses. The vertebral centra, in particular, presents elliptic pleurocoels showing an extrematelly developed neumatization. In the ilium, only the preacetabular blade is well preserved. The dorsal end of this blade is rounded. Although the preserved material is scarce, we preliminarily inferred from their general morphology and anatomical charasteristics of the vertebrae and pelvic elements that the Tratayén form represent a new large basal tetanuran taxon, possibly an allosauroid related to the Carcharodontosauridae, and then not related to the coelurosaurian or abelisauroid theropods.
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Journal of Vertebrate Paleontology Program and Abstracts, 2015
A majority of recent phylogenetic analyses of Tetanurae (Dinosauria: Theropoda) place basal (= non-coelurosaurian) tetanurans into clades Megalosauroidea and Allosauroidea forming successively closer outgroups to Coelurosauria. However, the positions of genera Cryolophosaurus, Sinosaurus, Monolophosaurus and Acrocanthosaurus and clade Megaraptora remain controversial and a few phylogenetic analyses question the monophyly of both Megalosauroidea and Allosauroidea. This presentation re-evaluates the phylogeny of non-coelurosaurian Tetanurae by re-examining highly distinct and size- and ecomorphology-independent states of several characters used in previous analyses. Cryolophosaurus possesses a small lesser trochanter, indicating it is among the most basal neotheropods (Coelophysis, Dilophosaurus). Sinosaurus retains a distally expanded scapula of the most basal neotheropods but shares with Ceratosauria & Tetanurae a large lesser trochanter, suggesting that it is more derived than the former but less derived than the latter. Spinosauridae and Carcharodontosauridae (except Acrocanthosaurus and Eocarcharia) possess a lesser trochanter extending proximally to the ventral margin of femoral head and lack a maxillary fenestra, suggesting that they are the most basal tetanurans. Piatnitzkysauridae, Metriacanthosauridae, Neovenator, Megaraptora, Megalosauridae, Acrocanthosauridae (Acrocanthosaurus, Eocarcharia) and Allosauridae (Allosaurus, Saurophaganax) share with basal Coelurosauria (Zuolong, Tanycolagreus, Coelurus, Tyrannosauroidea) a lesser trochanter extending proximally to the middle of femoral head (lesser trochanter extends proximally to the dorsal margin of femoral head in Megaraptora, Tyrannosauridae, and ornithomimosaur Beishanlong). The above basal tetanurans and Monolophosaurus also share with Coelurosauria a maxillary fenestra. Megalosauridae, Monolophosaurus, Acrocanthosauridae and Allosauridae share with Coelurosauria a posteroventrally expanded surangular contact of dentary and a metacarpal IV less than 25% of metacarpal III or absent, forming a clade Avetheropoda. Monolophosaurus, Acrocanthosauridae and Allosauridae also share with basal Coelurosauria (Zuolong, Tanycolagreus, Tyrannosauroidea, Ornitholestes) a robust dorsal ramus of quadratojugal, forming a clade Euavetheropoda. Allosauridae share with Coelurosauria a medially open maxillary antrum (evolved independently in Metriacanthosauridae and Eocarcharia).
Acta Palaeontologica Polonica
Neuquenraptor argentinus was described as the first undoubted deinonychosaurian theropod from Gondwana. The only known specimen is represented by a fragmentary skeleton, including a nearly complete foot, coming from Late Cretaceous beds of Neuquén Province, Patagonia, Argentina. Neuquenraptor was later considered as belonging to the Southern Hemisphere paravian clade Unenlagiidae, and proposed as a junior synonym of Unenlagia comahuensis. The aim of the present paper is to include a detailed anatomical description of Neuquenraptor (up to the date only known by a preliminary description). Comparisons with other paravians, especially unenlagiids, resulted in the finding of characters that may be considered as diagnostic of Unenlagiidae (e.g., scar-like fourth trochanter of femur, metatarsal II with tongue-shaped process over the caudal surface of metatarsal III, well-developed convex longitudinal plantar crest of metatarsal IV). Furthermore, comparisons between Neuquenraptor and Unenlagia are carried out with the aim to evaluate the possible synonymy between these taxa. These comparisons indicate that at least two similar-sized unenlagiids were present on the Portezuelo Formation. However, in concordance with previous authors, we are not able to support nor dismiss the possible synonymy between Unenlagia and Neuquenraptor. Additional findings of unenlagiid fossils from the Portezulo Formation will help to clarify the taxonomic status of these taxa.
Cretaceous Research, 2008
A new large theropod, Orkoraptor burkei nov. gen. et nov. sp., from the Upper Cretaceous (Maastrichtian) Pari Aike Formation of southern Patagonia is based on a postorbital, quadratojugal, coronoid?, several teeth, an atlantal intercentrum and neurapophysis, two caudal vertebrae, and the proximal half of tibia. This new theropod exhibits characteristics of maniraptorans (i.e., coelurosaurians more derived than tyrannosaurids) including an upturned rostral process of the postorbital, the caudoventral corner of which is widely concave. Furthermore, teeth without denticles and carina in the mesial margin resemble the condition of the maniraptoran clades Compsognathidae and Deinonychosauria. The new Patagonian theropod differs from other coelurosaurians (Ornithomimosauria, Compsognathidae, Alvarezsauridae, Dromaeosauridae, Aves) in having caudal vertebrae with a single pair of small pleurocoels on each side, and in having a median depression flanked by two longitudinal and narrow furrows on each tooth. Orkoraptor represents one of the southernmost carnivorous dinosaurs yet found in South America and adds valuable information about the diversification of tetanuran theropods in Gondwana.
Revista del Museo Argentino de Ciencias Naturales, 2006
Here we describe a partial humerus of a medium-sized theropod dinosaur from the Upper Cretaceous (Late Turonian-Early Coniacian) Portezuelo Formation, Neuquén Province, Argentina. The humerus shares with Abelisauroidea and Elaphrosaurus an articular head proximally oriented, and deltopectoral crest strongly reduced. The bone is referred to Abelisauroidea on the basis of the following derived features: proximal tuberosity on caudal surface of humeral shaft, and greater tubercle at level with the medial tuberosity. The gracile morphology of the humerus, as well as the poor development of its medial tuberosity, resemble more Masiakasaurus than the condition present in abelisaurids (e.g., Carnotaurus, Aucasaurus), in which the humerus is more robust and the medial tuberosity is prominent. Available information demonstrates that during deposition of the Portezuelo Formation large and bulky abelisaurids (e.g., Ekrixinatosaurus) lived together with gracile and medium-sized abelisauroids.
Cretaceous Research, 2020
A new ceratosaurian theropod dinosaur, Huinculsaurus montesi gen. et sp. nov., is described here. This taxon is based on the last three dorsal vertebrae and the first and second sacral vertebrae found in association at Aguada Grande, Neuqu en Province, Argentina. Although fragmentary, Huinculsaurus shows a unique mix of features which differentiates it from all other theropods, including the sympatric abelisaurid Ilokelesia, and is diagnosed by prezygapophyseal articular facets twice longer than wide, anterior centroparapophyseal lamina strongly developed as an extensive lateral lamina in the posterior dorsal vertebrae, pneumatic foramina located ventrally to the postzygodiapophyseal lamina in the posterior dorsal vertebrae, posteriorly tapering postzygapophysis pointed posteriorly, and an accessory lamina bisecting the parapophyseal centrodiapophyseal fossa in the posterior dorsal neural arches. Phylogenetic analyses recovered Huinculsaurus as most closely related to the Late Jurassic Elaphrosaurus than to other Cretaceous abelisauroids, suggesting the persistence of the elaphrosaurine lineage in South America up to the early Late Cretaceous.
Zoological Journal of the Linnean Society, 2011
The diversification and early evolution of neosauropod dinosaurs is mainly recorded from the Upper Jurassic of North America, Europe, and Africa. Our understanding of this evolutionary stage is far from complete, especially in the Southern Hemisphere. A partial skeleton of a large sauropod from the Upper Jurassic Cañadón Calcáreo Formation of Patagonia was originally described as a 'cetiosaurid' under the name Tehuelchesaurus benitezii. The specimen is here redescribed in detail and the evidence presented indicates that this taxon is indeed a neosauropod, thus representing one of the oldest records of this clade in South America. A complete preparation of the type specimen and detailed analysis of its osteology revealed a great number of features of phylogenetic significance, such as fully opisthocoelous dorsal vertebrae, the persistence of true pleurocoels up to the first sacral vertebra, associated with large camerae in the centrum and supraneural camerae, and an elaborate neural arch lamination, including two apomorphic laminae in the infradiapophyseal fossa. The phylogenetic relationships of this taxon are tested through an extensive cladistic analysis that recovers Tehuelchesaurus as a non-titanosauriform camarasauromorph, deeply nested within Neosauropoda. Camarasauromorph sauropods were widely distributed in the Late Jurassic, indicating a rapid evolution and diversification of the group.z oj_723 605..662 Figure 2. A, schematic drawing of the type specimen of Tehuelchesaurus as found in the quarry, showing the semiarticulated position of the skeleton. B, outline reconstruction of Tehuelchesaurus, indicating recovered elements (rib fragments not shown). Scale bars = 100 cm. For abbreviations see text. PHYLOGENY OF TEHUELCHESAURUS 607
Cretaceous Research, 2018
Several remains of an abelisaurid theropod including a nearly complete sacral complex articulated with both ilia, the distal boot of the pubes, the furcula, teeth, and fragments of transverse processes of caudal vertebrae was discovered in the La Invernada fossil site, northern Patagonia from the Bajo de la Carpa Formation (Santonian). The sacrum exhibit features typical of abelisauroids as narrowing of the middle sacral centra, fused neural spines forming a continuous sheet and ventral bow of the sacrum, in lateral view. The furcula represents de first mention of this bone for a South American abelisaurid. The morphology observed in the transverse processes with distal end projected forward and sagittal ridge on the ventral surface allows its assignation to the clade Brachyrostra.
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AI
The specimen exhibits tall neural spines on vertebrae and elliptical pleurocoels with pronounced neumatization.
The newly identified theropod is dated to the Santonian-Late Cretaceous period.
The theropod is estimated to reach a length of approximately eight meters.
The discovery highlights the increasing diversity of non-avian theropods in Patagonia, especially with new expeditions.
Preliminary analysis suggests it is a basal tetanuran, potentially an allosauroid related to Carcharodontosauridae.
Palaeontology, 2005
Abstract: A new taxon of theropod dinosaur is described as Condorraptor currumili gen. et sp. nov., from the Middle Jurassic (Callovian) Cañadón Asfalto Formation of Chubut Province, Argentinean Patagonia. The taxon is represented by a single fragmentary postcranial skeleton. Although incompletely known, Condorraptor is the second most complete theropod from the Middle Jurassic of Gondwana. The new taxon is characterized by the absence of a posterior incision between the fibular condyle and the medial side of the proximal articular end of the tibia, the pleurocoels in the anterior cervicals being situated posteroventral to the parapophyses, and the presence of a pronounced ‘step’ between the distal articular facet and shaft of Mt IV. Pneumatic features of the vertebral column show strong variation between the left and right side. Condorraptor gen. nov. can be referred to the Tetanurae and is a representative of a global radiation of basal tetanurans in the Early to Mid Jurassic.
Cretaceous Research, 2017
Here, wedescribe newtheropod materials (several isolated teeth, an axis, two caudal centra anda proximal left tibia) fromthe type locality of theBajada Colorada Formation (Lower Cretaceous, Berriasian-Valanginian).Although fragmentary, the recovered material shows a diverse association of meat-eating dinosaurs for this poorly undestood period of time. Three techniques were used to assess the phylogenetic position of the isolated teeth: multivariate (PCA), discriminant and phylogenetic analyses. The morphotypes 1, 2 and 3 (small non-recurved isolated crowns) were regarded as Theropoda indet.,as our analyses failed to supporta more precise classification. Two large almost complete ziphodont crowns, considered morphotype 4, were identified as belonging to megalosaurid tetanurans by phylogenetic, discriminantand multivariate analyses, thus likely representing the first record of this ancient family in South America, and the youngest worldwide. We refer the axis to a small abelisauroid ceratosaurian based on the following suite ofcharacters; long and pointed epipophyses,a pneumatic foramen in the centrum,the invaginated spinopostzygapophyseal lamina, and the anteroposteriorly long, dorsally convex, anddorsally/posteriorly unexpanded neural spine. The caudal centra can be referred to a theropod, and tentatively to Abelisauroidea, suggesting that theymay belong to the same taxon than that represented by the axis.The tibia lacks the incisura tibialis, presents a low, sharp and proximally positioned fibular crest,and has a deep lateral fossa, which islimited dorsally by a coarse, rounded in section and anteriorly directed crest.This combination of features allowsto refer it to a large abelisaurid. The Bajada Colorada dinosaur recordincludes so fara small abelisauroid, a large abelisaurid,aprobably medium to large megalosaurid tetanuran,diplodocid and dicraeosaurid sauropods. It shows some similarities with Middle and Upper Jurassic units in centralPatagonia, Africa and Portugal,suggesting that no significant dinosaur faunal turnover took place through the Jurassic-Cretaceous event inthe southern part of South America.
The present contribution describes theropod remains coming from the Huincul Formation (Neuquén Group; Cenomanian-Turonian; Upper Cretaceous) at a single locality located in northwestern Río Negro province, Patagonia, Argentina. This theropod association is composed of abelisauroids, two different-sized carcharodontosaurid allosauroids, a coelurosaur of uncertain relationships, a megaraptoran tyrannosauroid, and a possible unenlagiid paravian. Two new theropod genera and species are here described. The new carcharodontosaurid is based on an isolated postorbital bone bearing a unique prominence above the orbital brow. The new megaraptoran of uncertain affinities is described on the basis of a partially articulated tail and sacral vertebra. A new taxon is characterized by having notably elongate and highly pneumatic sacral and caudal vertebrae. It shows a large number of similarities with the African taxa Deltadromeus and Baharisaurus. These genera probably constitute a still poorly known clade of megaraptoran tyrannosauroids different from the Megaraptoridae. These findings support that Patagonia is a key place for understanding theropod evolution in Gondwana.
2013
The theropod clade Carcharodontosauridae is a broadly distributed group of large allosauroid theropods. The carcharodontosaurids recorded in the Albian – Cenomanian of Gondwana are the youngest and most derived members of this clade. Tyrannotitan chubutensis, from the Cerro Castan˜ o Member of Cerro Barcino Formation (Albian; Chubut Group), Central Patagonia, Argentina, is of prime interest among Gondwanan carcharodontosaurids as it represents the oldest record of the group. Here we offer a detailed osteological comparative description of the holotype and paratype of Tyrannotitan chubutensis together with a new diagnosis of the species. The new information results in a better understanding of this taxon and Carcharodontosauridae. Furthermore, a comparative study of the anatomy of the pectoral girdle of Giganotosaurus is reinterpreted as very similar to that of Tyrannotitan and Mapusaurus. We also present a phylogenetic analysis of Carcharodontosauridae that recovers Tyrannotitan as a derived carcharodontosaurid, being the sister group of the clade formed by Giganotosaurus and Mapusaurus, all nested in the clade Giganotosaurini
Revista del Museo Argentino de Ciencias Naturales, 2004
A large and diverse collection of vertebrate remains from the Campanian-Maastrichtian Allen Formation (Malargiie Group) a t the Bajo de Santa Rosa locality (Rio Negro Province, Argentina) is described hore. The vertebrates arc represented hv: chondrichthvans: di~iomvstid siluriform. le~isosteid, cf oercichthvid and titanosaurid dinosaurs. A now small salt,asaurine tit&saurid, I3onatitan reigigen. el sp. no"., is described. It is diagnosed by the following association of characters: 1) longitudinal groovo located an the suture between pariotals that continues posteriorly over the supraoccipital to the foramen magnum; 2) basisphcnoid tubera long and narrow; 3) dorsalto middle caudal vertebrae with deep oval to circular pits present on both sides of the prespinal lamina; 4) anterior caudal vertebra with spino-postzygapophysiat and spino-prezygapophysiai laminae; 5) neural arch of anterior caudals with deep interzygapophysial fossae with numerous pits; 6 ) anterior caudal vertebra with an accessom sub-horizontal lamina extendine from the antero-ventral oortion of the " postzygapophysis to the mid-portion of tho spino-prezygapophysial lamina; and finally, 7) anterior caudal vertobra with a prominent axial crest on the ventral surftaee of tho cerntrum. The first rocord of sphenodonts and cf carcharodontosaurid theropods is recognized for the upper Late Cretaceous ofpatagonia, as well as the earliest record of perichthylds (Pereiformes). The vertebrate record is mainly composed of terrestrial and freshwater tawa, but a few marine elements are found (olasmosaurids) indicating a marine influence during the deposition of the Allen hrmation in the arca of Baio de Santa Rosa. The vertebrate remains s u ~~o r t a Cam~anianand extra Patagonlan South Amencan records
Cretaceous Research, 2020
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Gaia, 2000
A new abelisaur theropod, Ilokelesia aguadagrandensis gen.nov., sp.nov., is described, characterized by having: a) quadrate with lateral condyle very reduced and posterior border of the articular surface formed completely from medial condyle, b) cervical vertebrae with very reduced diapo-postzygapophysial laminae, c) posterior dorsal vertebrae with infraparapophysial laminae ventrally concave, with parapophyses ventrally oriented, d) dorsal vertebrae lacking pleurocoels, e) caudal vertebrae in central third of the tail with distally expanded transverse processes bearing cranially and caudally projected processes and f) distal edge of caudal transverse processes slightly concave in the mid part. This new theropod represents the most plesiomorphic abelisaur taxon, sharing with Abelisauridae (Abelisaurus BONAPARTE & NOVAS, 1985 and Carnotaurus BONAPARTE, 1985) and Noasauridae (Noasaurus BONAPARTE & POWELL, 1980 and Ligabueino BONAPARTE, 1996) supraorbital ossification of postorbital, postorbital with intraorbital projection in the jugal process, quadrate with lateral condyle reduced, cervical vertebrae with reduced neural spine, well developed prezygo-epipophyseal laminae and distally expanded caudal transverse processes. Ilokelesia gen. nov. retains postorbital with jugal process perpendicular to horizontal branch, quadrate foramen and cervical epipophyses lacking cranial projection. RESUMEN: Se describe un nuevo terópodo abelisaurio, Ilokelesia aguadagrandensis gen. nov., sp.nov. caracterizado por poseer: a) cuadrado con cóndilo externo muy reducido y borde posterior de la superficie articular completamente formado por el cóndilo interno, b) vértebras cervicales con lámina diapo-postzigapofisial muy reducida, c) vértebra dorsal con lámina infraparapofisial ventralmente cóncava, con parapófisis orientadas ventralmente, d) vértebra dorsal posterior sin pleurocelos, e) vértebras caudales del tercio central de la cola con procesos transversos expandidos distalmente con procesos orientados cranial y caudalmente y f) procesos transversos caudales ligeramente cóncavos en la parte media. Este nuevo terópodo representa el taxón abelisaurio más plesiomórfico, compartiendo con Abelisauridae (Abelisaurus BONAPARTE & NOVAS, 1985 y Carnotaurus BONAPARTE, 1985) y Noasauridae (Noasaurus BONAPARTE & POWELL, 1980 y Ligabueino, BONAPARTE, 1996) osificación supraorbital del postorbital, postorbital con proyección intraorbital en el proceso jugal, cuadrado con el cóndilo externo reducido, vértebras cervicales con espinas neurales reducidas, lámina prezigo-epipofisial bien desarrollada y procesos transversos caudales expandidos distalmente. Ilokelesia gen. nov. retiene postorbital con proceso jugal perpendicular a la rama horizontal, foramen cuadrado y epipófisis cervicales carentes de proyección cranial.
Zoological Journal of the Linnean Society, 2011
Titanosauria is a taxonomically and morphologically diverse clade of sauropod dinosaurs that appeared in the Middle Jurassic and radiated in the mid-Late Cretaceous; however, its intrarelationships are poorly understood. The mid-Cretaceous Argentinean sauropod Andesaurus delgadoi has repeatedly been recovered at the base of Titanosauria, and thus represents a crucial taxon for determining the evolutionary history of this clade; yet it has only received a brief description. Here, we re-describe the holotype, comprising dorsal, sacral, and caudal vertebrae, as well as limb and pelvic elements. Detailed comparisons are made with a global array of titanosauriforms. Andesaurus is a valid genus and can be diagnosed by five autapomorphies: (1) posterior dorsal neural spine height greater than twice centrum height (autapomorphic within Macronaria); (2) square-shaped anterior-middle caudal centra in lateral view; (3) anteroposteriorly elongate fossa present on the anterodorsal corner of the lateral surface of middle-posterior caudal centra; (4) ridge along the midshaft of the ventral surface of metacarpal I, close to the ventromedial margin; (5) prominent ventromedial ridge along the distal half of metacarpal V. Other remains previously attributed to Andesaurus cannot be referred to this genus. Sixteen putative titanosaur synapomorphies can be recognized in Andesaurus, including: (1) lateral pneumatic foramina in dorsal vertebrae situated within fossae; (2) anterior-middle caudal vertebrae with ventrolateral ridges either side of a ventral midline hollow; and (3) lateral bowing of metacarpal I. This revision provides an important foundation for future phylogenetic analyses of titanosaurs, and adds to our growing understanding of this enigmatic clade. Lastly, we recommend the disuse of the coordinated suprageneric rank taxa of Andesaurus (Andesaurinae, Andesauridae, and Andesauroidea), at least until titanosaur intrarelationships are better elucidated.
Jorge Orlando Calvo