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CT scans of the type braincase of Limaysaurus tessonei (MUCPv-205) allowed the first study of the endocranial cavities (brain and inner ear) for this South American taxon. Comparisons of the cranial endocast of L. tessonei with other sauropods indicate that 1) South American rebbachisaurids are more similar to each other than to Nigersaurus, and 2) certain association of traits are present in all known rebbachisaurid cranial endocasts, such as lack of an enlarged dorsal expansion, poorly laterally projected cerebral hemispheres, presence of a small flocculus of the cerebellum, markedly long passage for the facial nerve (CN VII), markedly inclined pituitary, and presence of a passage for the basilar artery communicating the floor of the endocranial cavity and the pituitary fossa. The relatively enlarged olfactory region indicates that smell was an important sense for this group of dinosaurs, suggesting different olfactory capabilities when compared to coeval titanosaurs.

Fil: Rozadilla, Sebastián. Laboratorio de Anatomía Comparada y Evolución de Los Vertebrados, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina. Fil: Cruzado Caballero, Penélope. CONICET e Instituto de Investigación en Paleobiología y Geología, Sede Alto Valle-Valle Medio-Universidad Nacional de Río Negro; Argentina. Fil: Calvo, Jorge O. Grupo de Transferencia Proyecto Dino. Facultad de Ingeniería, Universidad Nacional del Comahue. Parque Natural Geo-Paleontologico Proyecto Dino; Argentina. Fil: Cruzado Caballero, Penélope. Universidad Nacional de Río Negro. Instituto de Investigación en Paleobiología y Geología. Río Negro, Argentina. Macrogryphosaurus gondwanicus is the largest Elasmaria (Dinosauria, Ornithischia) known up to the date, from the Upper Cretaceous of Patagonia. The present contribution provides a detailed description of Macrogryphosaurus anatomy based on the holotype and only known specimen. This dinosaur presents several unique features along its vertebral column that distinguishes it from other ornithopods: the neck is notably elongated by the acquisition of an additional cervical vertebra, having 10 cervical plus 14 dorsal vertebrae, being the number of dorsals minor than in other taxa, which usually have 16. This implies that Macrogryphosaurus represents a new ornithopod morphotype, with long neck and short thorax. Moreover, three autapomorphies are here added to the original diagnosis of Macrogryphosaurus: presence of poorly developed diapophyses in the cervical vertebrae, anterior and posterior processes on the boatshaped haemal arches, and a pubic foot in the postpubic process. The dorsoventral length of haemal arches indicate the ventral limit of the M. caudofemoralis longus and their posterior tapering so as the dorsal limit of the M. ilio-ischiocaudalis and its posterior ascension and dominance in the posterior-most portion of tail, resembling to the tail of some coelurosaur dinosaurs

espanolUna de las areas mas importantes de huellas de dinosaurios de Argentina se encuentra en la costa oeste del embalse Ezequiel Ramos Mexia, en la provincia de Neuquen. Con mas de 100 km de linea de costa, centenares de huellas han sido reconocidas en casi 30 anos. Las huellas se encuentran en la Formacion Candeleros, Grupo Neuquen, con una antiguedad Albiano?-Cenomaniano Inferior. Un estudio de detalle y revision de las huellas descritas hace casi 30 anos, es reevaluado y mejorado. Se describe un nuevo icnogenero: Candeleroichnus canalei icnogen. nov. icnosp. nov. Se selecciono un neotipo para Deferrariischnium mapuchensis Calvo, 1991 y se enmienda su diagnosis. Se amplia la diagnosis de Picunichnus benedettoi Calvo, 1991 con el hallazgo de pistas que permiten establecer distancia y angulo de paso. Se analizan todos los sitios descubiertos en la costa oeste del embalse y se identifican todas las icnoformas reconocidas, incluidas Sousaichnium monettae, Limayichnus major, Abelichnus astigarrae y Sauropodichnus giganteus en los distintos yacimientos. Se incluyen nuevas figuras, fotos y tablas sobre los icnotipos. EnglishIn Argentina, some of the most important dinosaur tracksites are found on the west coast of the Ezequiel Ramos Mexia reservoir, in the Neuquen province. In the last 30 years, more than 100 km of coastline have yielded hundreds of dinosaur tracks. The tracks are part of the Albian?-lower Cenomanian Candeleros Formation, Neuquen Group. An extensive study and review of the dinosaur tracks described in the past 30 years is reinterpreted and revised. Candeleroichnus canalei ichnogen. nov. ichnosp. nov. is described. A neotype is chosen for Deferrariischnium mapuchensis Calvo, 1991 and an emended diagnosis improves the ichnospecies. In addition, new information of the trackway diagnosis of Picunichnus benedettoi Calvo, 1991, such as length of pace and pace angle is given. We analyze all the dinosaur sites discovered until now and we identify all described ichnoforms such as Sousaichnium monettae, Limayichnus major, Abelichnus astigarrae and Sauropodichnus giganteus. We include unpublished figures, photos and tables of the ichnotypes

Un nuevo saurópodo titanosaurio del Cretácico Superior del Neuquén, Choconsaurus baileywillisi gen. et sp. nov., es descripto. La especie se halla representada por huesos de diferentes partes del esqueleto, incluyendo una serie casi completa de vértebras dorsales. El material proviene de la localidad de Villa El Chocón, y estratigráficamente de la Formación Huincul, cuya edad ha sido estimada como Cenomaniano superior. El nuevo taxón presenta características autapomórficas, entre ellas, la presencia de una pequeña escotadura sobre el margen dorsal de la superficie articular posterior de los centros cervicales, articulaciones accesorias laterales al hipósfeno, las cuales están más desarrolladas en las vértebras dorsales anteriores, vértebras dorsales medias y posteriores con una lámina accesoria ubicada entre las láminas centrodiapofisial posterior y centrodiapofisial posterior accesoria, e hipósfeno en las vértebras caudales anteriores. El análisis filogenético ha recuperado a la nueva especie como un titanosaurio no-eutitanosaurio. Formas basales de titanosaurios están bien representadas en el Cretácico Superior bajo de Patagonia; Choconsaurus baileywillisi es, a la fecha, el titanosaurio no-eutitanosaurio más completo. Palabras clave.Titanosaurio. Cretácico Superior. Provincia de Neuquén. Villa El Chocón. A new titanosaur sauropod from the Upper Cretaceous of Neuquén is described, Choconsaurus baileywillisi gen. et sp. nov. The species is represented by a nearly complete series of dorsal vertebrae as well as other parts of the skeleton. The material comes from the locality of Villa El Chocón and stratigraphically from the Huincul Formation, whose age has been estimated as upper Cenomanian. The new taxon presents many autapomorphic features, including the presence of a small notch on the dorsal margin of the posterior articular surface of the cervical centra, accessory articulations lateral to the hyposphene, which are more developed in the anterior dorsal vertebrae, midand posterior dorsal vertebrae with an accessory lamina placed between the posterior centrodiapophyseal and the accessory posterior centrodiapophyseal laminae, and a hyposphene on anterior caudal vertebrae. Phylogenetic analysis recovers Choconsaurus baileywillisi as a non-eutitanosaur titanosaur, taxa that are well represented in the lower Upper Cretaceous of Patagonia. Choconsaurus baileywillisi is, to date, the most complete non-eutitanosaur titanosaur. Fil: Simón, Edith. Universidad Nacional del Comahue. Facultad de Humanidades. Departamento de Geografía; Argentina Fil: Salgado, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; Argentina Fil: Calvo, Jorge. Universidad Nacional del Comahue. Facultad de Ingeniería; Argentina

Upper Cretaceous (Turonian–Santonian) tracksites at Barreales Lake, Neuquen Province, Argentina are described. Tracksites studied for the last 20 years on the northern and northeastern coasts of the lake mainly contain theropod and sauropod tracks preserved as either natural molds, concave epireliefs, concave hyporeliefs, or convex hyporeliefs. Sauropod tracks and trackways represent taxa that exhibited wide-gauge locomotor styles. Based on their morphology and evidence from body fossils, they are interpreted as having been produced by titanosaurs. Theropod tracks are represented by tridactyl prints with claw impressions. Some of the theropod tracks are inferred as having been made by megaraptorids. The dinosaur track record of the Barreales Lake region spans several formations: the Portezuelo Formation yielded theropod tracks at the Baal, Punta Motorhome, Aguas Claras, and South Loma de la Lata sites; the Plottier Formation preserves sauropod and ornithopod tracks at the Proyecto Dino and Middle Loma de la Lata sites, respectively; and the Bajo de la Carpa Formation yielded sauropod and theropod tracks at the Querubin site. Here we describe all these dinosaur tracksites and make inferences regarding their paleoenvironments. A brief description of some invertebrate traces from the Querubin tracksite is also provided. The description of these tracks and trackways adds to knowledge of Late Cretaceous continental paleoecosystems of southern South America.

We describe a dentary of a new titanosaur sauropod, Baalsaurus mansillai, gen. et sp. nov. from the Late Cretaceous of Patagonia, Argentina. The material comes from the Portezuelo Formation, Neuquén Group. Titanosaur sauropods lower jaws are scarce and only nine taxa with dentaries have been described. There are two types of morphology in titanosaur dentaries; “L” shaped or “U” shaped based on the shape, without a phylogenetic issue. In this paper; we recognize a new taxa, Baalsaurus mansillai, represented by an “L” shaped dentary with three apomorphic characters that are not present in other taxa: dentary alveoli with 10 teeth in the anterior ramus, a ventrally and anteriorly inclined symphysis and a wide ventral Meckelian groove surrounded by a thin lamina that forms a keel on the ventral border of the dentary. Fil: Calvo, Jorge Orlando. Parque Natural Geo-Paleontológico Proyecto Dino.Grupo de Transferencia Proyecto Dino; Argentina. Universidad Nacional del Comahue. Facultad de Ingeniería. Departamento de Geología y Petróleo; Argentina. Universidad Nacional de La Pampa; Argentina Fil: Gonzalez Riga, Bernardo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina

Titanosauria is an exceptionally diverse, globally-distributed clade of sauropod dinosaurs that includes the largest known land animals. Knowledge of titanosaurian pedal structure is critical to understanding the stance and locomotion of these enormous herbivores and, by extension, gigantic terrestrial vertebrates as a whole. However, completely preserved pedes are extremely rare among Titanosauria, especially as regards the truly giant members of the group. Here we describe Notocolossus gonzalezparejasi gen. et sp. nov. from the Upper Cretaceous of Mendoza Province, Argentina. With a powerfully-constructed humerus 1.76 m in length, Notocolossus is one of the largest known dinosaurs. Furthermore, the complete pes of the new taxon exhibits a strikingly compact, homogeneous metatarsus—seemingly adapted for bearing extraordinary weight—and truncated unguals, morphologies that are otherwise unknown in Sauropoda. The pes underwent a near-progressive reduction in the number of phalanges along the line to derived titanosaurs, eventually resulting in the reduced hind foot of these sauropods.

The Neuquén Basin has yielded a highly diverse fauna of sauropod dinosaurs. This group includes diplodocoids (e.g., Salgado and Bonaparte, 1991; Salgado et al., 2004; Haluza et al., 2009) and titanosaurs (e.g., Lydekker, 1893; Calvo and Bonaparte, 1991; Bonaparte and Coria, 1993; Salgado and Azpilicueta, 2000; Apesteguía, 2004; González Riga, 2003; Filippi et al., 2011). The plentiful record of titanosaur sauropods in the Upper Cretaceous of northern Patagonia is mostly restricted to derived titanosaurs included in the Titanosauridae (=Lithostrotia sensu Upchurch et al., 2004). Derived titanosaurs were traditionally characterized by the possession of strongly procoelous anterior-middle caudal vertebrae. This feature was used as a diagnostic trait to differentiate them from basal forms of titanosaurs with amphiplatyan or am- phicoelous caudal vertebrae (Salgado et al., 1997). However recent discoveries have demonstrated that a great variation exists throughout the titanosaurian caudal series (Salgado and Calvo, 1993; Wilson et al., 1999; Calvo and González Riga, 2003; González Riga et al., 2009). In this sense, procoely appears to be non-continuous along the tail, implying a very different morphological scenario. In this paper we report a series of sauropod caudal vertebrae collected from the upper levels of the Candeleros Formation (Neuquén Group) near Villa El Chocón, Neuquén Province, Argentina. The materials, previously referred tentatively to Andesaurus (Otero et al., 2006), include a discontinuous series of mid and mid-posterior caudal vertebrae,most of them including their haemal arches. The latter elements present an unusual morphology hitherto not reported in other sauropod dinosaurs. Fil: Otero, Alejandro. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Canale, Juan Ignacio. Provincia del Neuquén. Municipalidad de Villa El Chocón. Museo Paleontológico "Ernesto Bachmann"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Haluza, Alejandro. Provincia del Neuquén. Municipalidad de Villa El Chocón. Museo Paleontológico "Ernesto Bachmann"; Argentina Fil: Calvo, Jorge Orlando. Universidad Nacional del Comahue. Centro Paleontológico Lago Barreales; Argentina

A NEW CRETACEOUS MESOEUCROCODYLIA FROM THE NORTH OF THE NEUQUEN BASIN, ARGENTINA. In this contribution, a new specimen of Mesoeucrocodylia from levels attributed to the Plottier Formation (Cretaceous, Upper Coniacian) is described in the locality Yacimiento Narambuena, Rincon de los Sauces, in the north section of the Neuquen Province. The material includes an incomplete subadult specimen with mostly articulated postcranium of an approximate length of 60 cm. The study and comparisons to allow distinguish the specimen from other Mesoeucrocodylia previously known from this same basin and suggest the presence of a new taxon, increasing the diversity of this clade in this period in the Neuquen Basin. The specimen from Rincon de los Sauces presents postcraneal characters previously attributed to Notosuchia and Neosuchia, both clades mainly defined by cranial characters. This set of primitive and derived characters prevents the location of its precise phylogenetic position among the Mesoeucrocodylia.

Agua del Choique is a new Late Cretaceous sauropod track site from Mendoza Province, Neuquen Basin, Argentina. It is situated in the Loncoche Formation, late Campanian - early Maastrichthian in age, and is one of the youngest sauropod tracks site recorded in the world. Agua del Choique represents a lake setting and river-dominated delta deposits, and comprises at least 160 well-preserved tracks, located on a calcareous sandstone bed. A new ichno- taxon, Titanopodus mendozensis ichnogen. et ichnosp. nov., is erected for the footprints of this track site. Titanopodus mendozensis exhibits the following association of features: (1) wide-gauge trackway (manus and pes trackway ratios of 18- 22 and 26-31 per cent respectively), (2) pronounced het- eropody (manus-pes area ratio of 1:3), (3) outer limits of trackway defined, in some cases, by the manus tracks, and (4) manus impression with an asymmetrical crescent contour and acuminate external border. Titanopodus mendozensis is an excellent case study of the wide-gauge style of locomotion produced by Late Cretaceous derived titanosaurs that have no impression of manual phalanges. These features, and the fossil record from the Loncoche Formation, suggest that the trackmakers were, probably, middle size saltasaurine or aeolosaurine titanosaurs (14-16 m long).

Fossils of a predatory dinosaur provide novel information about the evolution of unenlagiines, a poorly known group of dromaeosaurid theropods from Gondwana. The new dinosaur is the largest dromaeosaurid yet discovered in the Southern Hemisphere and depicts bizarre cranial and postcranial features. Its long and low snout bears numerous, small-sized conical teeth, a condition resembling spinosaurid theropods. Its short forearms depart from the characteristically long-armed condition of all dromaeosaurids and their close avian relatives. The new discovery amplifies the range of morphological disparity among unenlagiines, demonstrating that by the end of the Cretaceous this clade included large, short-armed forms alongside crow-sized, long-armed, possibly flying representatives. The new dinosaur is the youngest record of dromaeosaurids from Gondwana and represents a previously unrecognized lineage of large predators in Late Cretaceous dinosaur faunas mainly dominated by abelisaurid theropods. Fil: Novas, Fernando Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Pol, Diego. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Canale, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Provincia del Neuquén. Municipalidad de Villa El Chocón. Museo Paleontológico "Ernesto Bachmann"; Argentina Fil: Porfiri, Juan Domingo. Universidad Nacional del Comahue; Argentina Fil: Calvo, Jorge Orlando. Universidad Nacional del Comahue; Argentina

Most titanosaur dinosaurs are represented by incomplete skeletal elements lacking articulated pes. An exceptionally preserved specimen from the Late Campanian–Early Maastrichtian strata of Patagonia (Argentina) provides new data on pedal morphology and the evolutionary trends of these huge dinosaurs. This finding is one of the few articulated titanosaur pes known in the world, and shows a phalangeal formula of 2-2-2-2-0. The first three digits possess sickle-shaped claws and the articular facets of ungual phalanges, suggesting mobility in horizontal and vertical planes. A comparative analysis of available record suggests that titanosaurs had a progressive reduction of size and number of pedal phalanges in digits III and IV during the Late Cretaceous.

A well-preserved dentary from the Late Cretaceous of Neuquen Province, Argentina, represents a new taxon of sebecosuchian crocodyliform, Pehuenchesuchus enderi. The specimen retains a number of diagnostic characters and is referable to Sebecosuchia on the basis of two derived features (a longitudinal groove on the lateral surface of the dentary and a sigmoidal tooth row in dorsal view). The new taxon differs from all other sebecosuchians by possessing laterally compressed teeth that lack serrated carinae. A phylogenetic analysis of 30 crocodyliform taxa and two character-taxon matrices, which include many putative sebecosuchians, supports a monophyletic Sebecosuchia. In both analyses, Pehuenchesuchus enderi was resolved as the sister taxon to all other sebecosuchians. A clear division of Sebecosuchia into Sebecidae and Baurusuchidae was not supported.

We report the discovery of a new titanosaurian taxon, Puertasaurus reuili gen. et sp. nov., from Maastrichtian beds of SW Patagonia. Four vertebrae were recovered (i.e., cervical 9, dorsal 2, and two mid-caudals). The new form is diagnosed on the basis of an inflated neural spine on cervical vertebra, and extremely short second dorsal vertebra, among other features. Puertasaurus is one of the largest known sauropod dino-saurs, with dorsal vertebra 2 measuring 168 cm in transverse width. This is the first time that a cervical verte-bra is reported for a giant titanosaur, giving a new insight on neck anatomy of neosauropod dinosaurs.

The discovery of a new iguanodontian ornithopod in the lower units of the Neuquen Group (Rio Limay Formation, early Upper Cretaceous) increases the South American record of this kind of dinosaurs started few years ago with the report of Gasparinisaura cincosaltensis. Anabisetia saldiviai, gen. et sp. nov. is distinguished from all other ornithopods by several features, as a flattened fifth metacarpal, a scapula with a very strong acromial process, and an ilium with preacetabular process longer than 50% of the total ilium length. Anabisetia is more derived than Tenontosaurus and shares with Euiguanodontia (Gasparinisaura + Dryomorpha) the presence of one primary lateral ridge on each maxillary tooth, a broad brevis-shelf and a reduced first metatarsal. Derived features such as the transversely flattened prepubic process and an anteroventrally oriented ischiadic foot link Anabisetia with Dryomorpha (i.e., Dryosaurus, Camptosaurus and Iguanodon). Anabisetia strengths the hypothesis that basal iguano...

(2002). Late Cretaceous avian eggs with embryos from Argentina. Journal of Vertebrate Paleontology: Vol. 22, No. 1, pp. 191-195.

Megaraptorids are a group of predatory dinosaurs that inhabited Gondwana from Cenomanian to Santonian times (Late Cretaceous). Phylogenetic relationships of megaraptorids have been matter of recent debate, being alternatively interpreted as basal coelurosaurs, carcharodontosaurian allosauroids, megalosauroids, and basal tyrannosauroids. One of the main reasons for such different interpretations is the incomplete nature of most available megaraptorid skeletons and, in particular, the scarce information about their cranial anatomy. Here we describe a partially preserved skeleton of a juvenile specimen of Megaraptor namunhuaiquii that provides substantial new information about the cranial morphology of this Patagonian taxon. The specimen comes from the Upper Cretaceous (Turonian–Coniacian) of the Portezuelo Formation, northwestern Patagonia, Argentina. The anatomy of the new specimen bolsters the recently proposed hypothesis that megaraptorids are nested within Coelurosauria, and possibly within Tyrannosauroidea. The most relevant features that megaraptorans share with tyrannosauroids include several foramina on the premaxillary body, extremely long and straight prenarial process of the premaxilla, incisiviform premaxillary teeth with a D-shaped cross-section, and cranially expanded supratemporal fossae separated from each other by a sharp sagittal median crest on frontals, which was presumably extended caudally above the parietals (not preserved). Information gathered from the present specimen allows to make for the first time a reconstruction of the skull of Megaraptor and hypothesize about evolutionary trends within Tyrannosauroidea. Fil: Porfiri, Juan D.. Universidad Nacional del Comahue. Centro Paleontologico Lago Barreales; Argentina Fil: Novas, Fernando Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina Fil: Calvo, Jorge. Universidad Nacional del Comahue. Centro Paleontologico Lago Barreales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Agnolin, Federico L.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina. Fundacion de Historia Natural Felix de Azara; Argentina Fil: Ezcurra, Martin Daniel. University of Birmingham. School of Geography, Earth and Environmental Sciences; Reino Unido. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Cerda, Ignacio Alejandro. Universidad Nacional de Rio Negro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Pterosaur tracks from the Candeleros Member of the Rio Limay Formation (Albian–Cenomanian) at Lake Ezequiel Ramos Mexia, Neuquen Province, Argentina, are the first pterosaurian tracks reported from South America and from the Southern Hemisphere. Although the individual footprints are not well preserved, some trackway segments and manus-pes sets are preserved, suggesting that the tracks can be assigned to cf. Pteraichnus ichnosp. indet. The palaeoenvironmental setting of the track beds is a lake shoreline, where dinosaur tracks also occur. The discovery is consistent with reports of well known pterosaur-bearing Lagerstatten in the Lower Cretaceous of South America.

Vertebrate remains from the Late Albian–Early Cenomanian Candeleros Formation of northwestern Patagonia include those of a pipoid frog, which is described herein. The fossils consist of partially articulated and disarticulated elements, some of them badly broken, that are mostly exposed in ventral aspect. The description is based on one incomplete skeleton that presumably belongs to a single individual; this specimen possesses a combination of character states not present in other known non-palaeobatrachid pipimorph taxa and is identified here as a new genus and species, Avitabatrachus uliana. The species is moderately small (estimated snout-vent length ca. 35 mm) and shares with Pipidae conch-like squamosals, deeply excavated prootics to form channels for the Eustachian tubes, articulations for the lower jaws at the anterolateral corners of otic capsules, and fused sacrum and urostyle. Avitabatrachus possesses at least eight presacral vertebrae, the first two of which are fused, with flat, opist...

A new species of the genus Araripesuchus from the Albian-Cenomanian locality of the El Chocon (Neuquen Province, Argentina) is described. The diagnosis of the genus is reviewed and its phylogenetic placement within Crocodylomorpha discussed. Araripesuchus is proposed here as being the sister taxon of Neosuchia, corroborating previous phylogenetic analysis. The new species, Araripesuchus patagonicus, differs from the type species, A. gomesii in the relationships of the prefronto-nasal and lachrymo-nasal sutures, the dermal placement of the postorbital bar on the medial side of the jugal, and the greater extension of the squamosals in the skull dorsum. The African species, “Araripesuchus” wegeneri, does not share the diagnostic traits of the genus, and its reassignment to a new genus needs to be considered. The phylogenetic context of Araripesuchus and “A.” wegeneri permits a reanalysis of the role played by their amphiatlantic distribution in the Aptian-Albian. “Araripesuchus” wegeneri and the Sou...

Fil: Moreno, Karen. Universidad Austral de Chile. Laboratorio de Paleoecología. Valdivia, Chile. Fil: de Valais, Silvina. Universidad Nacional de Rio Negro. Instituto de Investigaciones en Paleobiologia y Geologia. Río Negro, Argentina. Fil: Blanco, Nicolás. Servicio Nacional de Geología y Minería. Santiago, Chile. Fil: Tomlinson, Andrew. Servicio Nacional de Geología y Minería. Santiago, Chile. Fil: Jacay, Javier. Universidad Nacional Mayor de San Marcos, EAP Ingeniería Geológica. Lima, Perú. Fil: Calvo, Jorge. Universidad Nacional del Comahue. Centro Paleontológico Lago Barreales. Neuquén, Argentina. In modern terrestrial ecosystems, the population size of large predators is low, and a similar pattern has usually been assumed for dinosaurs. However, fossil finds of monospecific, large theropod accumulations suggest that population dynamics were more complex. Here, we report two Early Cretaceous tracksites dominated by large theropod footprints, in Querulpa Chico (Peru) and Chacarilla (Chile). The two sites correspond to distinct depositional environments—tidal basin/delta (Querulpa Chico) and meandering river (Chacarilla)—with both subject to extensive arid or semiarid palaeoclimatic conditions. Although most trackways show no preferred orientation, a clear relationship between two trackmakers is observed in one instance. This observation, coupled with the high abundance of trackways belonging to distinct large theropods, and the exclusion of tracks of other animals, suggests some degree of grouping behaviour. The presence of freshwater sources in a dry climate and perhaps social behaviour such as pair bonding may have promoted interactions between large carnivores. Further, the occurrence of these two tracksites confirms that large theropod dinosaurs, possibly spinosaurids and/or carcharodontosaurids, existed on the western margin of Gondwana as early as the earliest Cretaceous.

A new genus and species of Late Cretaceous (Coniancian–Santonian) birds, Neuquenornis volans, is described. This new taxon is known from a fairly complete, articulated specimen from the Rio Colorado Formation of northwestern Patagonia. Synapomorphies of the humerus, radius, ulna, coracoid, femur, tibiotarsus, tarsometatarsus, and thoracic vertebrae, support its allocation to the Enantiornithes. The tarsometatarsal structure of Neuquenornis refers it to the Late Cretaceous family Avisauridae. The structure of the wing and pectoral girdle of Neuquenornis indicates that it was an active flyer, an aptitude also inferred for the El Brete enantiornithines from the Upper Cretaceous Lecho Formation of northwestern Argentina. The pedal structure of Neuquenornis and Soroavisaurus from El Brete, indicates that avisaurids were capable of perching in trees.

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. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011.

The fossil record of cranial material from titanosaurid sauropods is very poor and no complete skull has been described so far. Here we describe a new braincase (MUCPv-334) that was recovered from reddish sandstones of the Rio Colorado Subgroup (Late Cretaceous) of the region of Bajo del Añelo, approximately 20 km north of the town Añelo (Neuquén Province, Argentina). This specimen is attributed to the Titanosauridae based on the ventrally projected basipterygoid processes, a common condition shared by other titanosaurids. The robustness of MUCPv-334 together with an unusually expanded crista prootica and the presence of an anterior prolongation of the parasphenoid reaching the basal tubera were not reported in other members of the Titanosauridae, indicating a larger diversity in the braincase morphology of this sauropod clade than previously thought.

Rinconsaurus caudamirus gen. et sp. nov. (Dinosauria, Sauropoda) is a new and slender Titanosauridae. The specimens come from the Upper Cretaceous strata of the Río Neuquén Formation at Rincón de los Sauces, Neuquén Province, Patagonia, Argentina. The remains include 13 articulated caudal vertebrae and disarticulated cranial, cervical, dorsal and appendicular materials. These fossils belong to three individuals, two adults and one juvenile. This new species is characterized by the following association of autapomorphies: (1) neural spines in mid-anterior dorsal vertebrae inclined posteriorly more than 60 degrees with respect to the vertical, (2) middle caudal vertebrae with bony processes that support the articular surfaces of postzygapophyses, and (3) procoelous posterior caudal centra with intercalation of a series of amphicoelous-biconvex or amphicoelous-opisthocoelous-biconvex centra. A cladistic phylogenetic analysis placed Rinconsaurus in the family Titanosauridae. Within Titanosauridae (Rinconsaurus + Aeolosaurus) is considered a sister group of the clade (Opisthocoelicaudia + (Alamosaurus + (Neuquensaurus + Saltasaurus))). Rinconsaurus caudamirus has preserved short articulated posterior caudal series with amphicoelous, opisthocoelous and biconvex centra. This unusual morphology represents the first such occurrence in sauropod dinosaurs. From the systematic point of view, this discovery is important because Titanosauridae were traditionally defined, among other characters, by strongly developed procoelia in their caudal vertebrae Rinconsaurus caudamirus gen. et sp. nov., un nuevo titanosáurido (Dinosauria, Sauropoda) del Cretácico Tardío de Patagonia, Argentina. Rinconsaurus caudamirus gen et sp. nov. (Dinosauria, Saurpoda) es un nuevo y esbelto Titanosauridae proveniente de la Formación Río Neuquén, Cretácico Superior de Rincón de los Sauces, Provincia de Neuquén, Patagonia, Argentina. Sus restos están integrados por 13 vértebras caudales articuladas y materiales craneales, cervicales, dorsales y apendiculares desarticulados, que pertenecen a tres individuos, dos adultos y un juvenil. Este nuevo taxón se caracteriza por la siguiente asociación de autapomorfías: (1) vértebras dorsales medioanteriores con espinas neurales inclinadas posteriormente más de 60 grados con respecto a la vertical, (2) vértebras caudales medias con procesos óseos que sostienen las carillas articulares de las poszigapófisis y (3) vértebras caudales procélicas con intercalaciones de series con centros anficélicos y bioconvexos, o con centros anficélicos, opistocélicos y biconvexos. Un análisis filogenético cladista permite incluir a Rinconsaurus en la familia Titanosauridae. Dentro de Titanosauridae (Rinconsaurus +Aeolosaurus) es considerado un grupo hermano del clado (Opisthocoelicaudia + (Alamosaurus + (Neuquensaurus + Saltasaurus))). Rinconsaurus caudamirus presenta dos cortas secuencias caudales posteriores articuladas con centros anficélicos, opistocélicos y biconvexos. Esta inusual morfología se registra por primera vez en dinosaurios saurópodos. Es importante desde el punto de vista sistemático, ya que Titanosauridae ha sido tradicionalmente definido, entre otros caracteres, por la presencia de fuerte procelia en sus vértebras caudales

A new genus and species of clupeomorph fish, Leufuichthys minimus , is described from the fluvial deposits of the Portezuelo Formation, Upper Cretaceous (Turonian–Coniacian) of the Neuquen Group, Patagonia, Argentina. It is a small-sized fish with an estimated body length up to 46 mm. Among other characters, the new species shows the following: abdominal scutes; abdomen moderately convex; anal fin elongate-based; three uroneurals; two epurals; caudal fin bearing very elongate rays; and cycloid scales. Leufuichthys minimus gen. et sp. nov. shows a greater similarity with Kwangoclupea dartevellei , a clupeomorph described from a marine Cenomanian deposit of the Democratic Republic of Congo (Africa), mainly due to the presence of an elongate-based anal fin, bearing more than 20 fin-rays, differing from it by the presence of a not hypertrophied abdomen. As far as known, L. minimus gen. et sp. nov. is the first clupeomorph described in the Upper Cretaceous of Patagonia and represents one fortuitous preservation of an articulated fish in fluvial deposits.