Osteology and systematic phylogenetic of new titanosaurian sauropod dinosaurs from South America

Los dinosaurios saurópodos titanosaurios fueron los vertebrados herbívoros más grandes y abundantes en los ecosistemas del Cretácico Superior. Este proyecto comprende el estudio anatómico y filogenético de dos nuevas especies de titanosaurios, ampliando el conocimiento evolutivo de este clado. En los últimos años, el Director de este proyecto ha descubierto las primeras cuatro especies de titanosaurios procedentes de la provincia de Mendoza (Argentina), incluyendo el gigante Notocolossus, uno de los vertebrados terrestres más grandes del mundo. En este proyecto, se propone continuar el estudio de los titanosaurios mediante la descripción de dos nuevas especies, una de Chile (desierto de Atacama) y otra de Brasil (Minas Gerais), las que serán comparadas con nuevos fósiles de Mendoza (Argentina). Este proyecto se destaca por: (1) la conformación de un equipo internacional, (2) la capacitación de recursos humanos, tanto de estudiantes graduados como becarios postdoctorales, y (3) su relevancia socio-patrimonial para la región y país, incluida la consolidación del Laboratorio y Museo de Dinosaurios, recientemente creado. Este proyecto genera un impacto positivo en los campos cultural y educativo, especialmente en una región donde los recursos alternativos son importantes.Titanosaurian sauropod dinosaurs were the largest and abundant herbivorous vertebrates in the Late Cretaceous ecosystems. This project comprises the anatomical and phylogenetic study of two new titanosaur species, expanding our evolutionary knowledge of this clade. In recent years the Director of this project has discovered the first four titanosaur species of Mendoza province (Argentina), including the giant Notocolossus, one of the largest land vertebrate in the world. In this project, we propose to continue the study of titanosaurs with the description of two new species, one from form Chile (Atacama desert) and another one from Brazil (Minas Gerais). These fossils will be compared with new titanosaur fossils discovered in Mendoza Province. This project is highlighted for (1) an international teamwork, (2) the training of human resources, both for graduate and postdoctoral students, and (3) its socio-patrimonial relevance for this region and country, including the consolidation of the Laboratory and Museum of Dinosaurs, recently created. This project generates a positive impact in the cultural and educational fields, especially in a region where the alternative resources are important

Sauropod dinosaur tracks from South America: perspectives and paleobiological aspects

Ichnology gives relevant information to understand the paleobiology of sauropod dinosaurs, particularly in relation with two main aspects: locomotion (stance, gait, speed, centers of mass) and behavior (gregarious behavior, 'herd structure', habitats and sedimentary environments). Until now, these studies have been applied to the best known types of tracks and conclusions have been extended to other sauropods, regardless of the extraordinary diversity of this clade. In South America, some titanosaur tracksites from Bolivia and Argentina (Humaca, and Agua del Choique, respectively) exhibit sets of parallel trackways suggesting that the trackmakers traveled in social groups. Only two ichnotaxa have been described in South America: Sauropodichnus giganteus Calvo (Candeleros Formation, early Cenomanian of Neuquén) and Titanopodus mendozensis González Riga and Calvo (Loncoche Formation, late Campanian-early Maastrichtian of Mendoza). Titanopodus trackways represent an excellent case study of the widegauge style of locomotion produced by Aeolosaurini or Saltasaurinae titanosaurs. In this case, speed of the trackmakers was calculated throughout accurate estimations of hip height and gleno-acetabular distance, using for comparison an articulated titanosaurian specimen collected in correlative strata (Allen Formation, Neuquén Basin). Traditionally, the presence of wide-gauge trackways in titanosaurs was associated to a low heteropody (e.g., manus:pes ratio between 1:1 to 1:2). However, Titanopodus trackways show a moderate heteropody (∼1:2,6) associated with very wide trackways indicating that this general interpretation must be revised. It is probable that both heteropody and trackway ratio (ratio of the track width relative to the total trackway width) show variations during ontogenetic stages. Moreover, from an evolutionary perspective, variations of these parameters are related with the amazing diversity of the titanosaurs (represented by around 48 genera), a fact certainly ignored by most ichnological analyses.Simposio IV: Icnología: su aporte en interpretaciones paleoecológicas y paleobiológicasFacultad de Ciencias Naturales y Muse

Osteology of the Late Cretaceous Argentinean sauropod dinosaur Mendozasaurus neguyelap: implications for basal titanosaur relationships

The titanosaurian sauropod dinosaur Mendozasaurus neguyelap is represented by several partial skeletons from a single locality within the Coniacian (lower Upper Cretaceous) Sierra Barrosa Formation in the south of Mendoza Province, northern Neuquén Basin, Argentina. A detailed revision of Mendozasaurus, including previously undocumented remains from the holotype site, allows us to more firmly establish its position within Titanosauria, as well as enabling an emended diagnosis of this taxon. Autapomorphies include: (1) middle and posterior cervical vertebrae with tall and transversely expanded neural spines that are wider than the centra, formed laterally by spinodiapophyseal laminae that are not connected with the pre- or postzygapophyses; (2) anterior caudal vertebrae (excluding anteriormost) with ventrolateral ridge-like expansion of prezygapophyses; and (3) humerus with divided lateral distal condyle on anterior surface. New remains demonstrate that the presacral vertebrae of Mendozasaurus were not unusually short anteroposteriorly, with this compression instead resulting from taphonomic crushing. Comparative studies of articulated pedes of other taxa allow us to interpret that the pedal formula of Mendozasaurus was 2-2-2-2-0, based on disarticulated bones that form a right hind foot. Mendozasaurus was incorporated into an expanded version of a titanosauriform-focussed phylogenetic data matrix, along with several other contemporaneous South American titanosaurs. The resultant data matrix comprises 84 taxa scored for 423 characters, and our phylogenetic analysis recovers Mendozasaurus as the most basal member of a diverse Lognkosauria, including Futalognkosaurus and the gigantic titanosaurs Argentinosaurus, Notocolossus, Patagotitan and Puertasaurus. Lognkosauria forms a clade with Rinconsauria (Muyelensaurus + Rinconsaurus), with Epachthosaurus and Pitekunsaurus recovered at the base of this grouping. A basal lithostrotian position for this South American clade is well supported, contrasting with some analyses that have placed these taxa outside of Lithostrotia or closer to Saltasauridae. The sister clade to this South American group is composed of an array of near-global taxa and supports the hypothesis that most titanosaurian clades were widespread by the Early–middle Cretaceous

Hallazgo de tiburones cretácicos (Chondrichthyes) en la provincia de Mendoza (Argentina): aspectos estratigráficos y paleoambientales

Se comunica el hallazgo de dientes de tiburones cretácicos en la provincia de Mendoza, región septentrional de la Cuenca Neuquina, Argentina. Los restos, colectados entre los años 2001-2009, provienen de los niveles basales de la Formación Jagüel aflorantes en el anticlinal de Ranquil-Có, Sierra de Palauco, sur del Departamento de Malargüe. En ese sector los estratos cretácicos de los Grupos Neuquén y Malargüe afloran completos desde su base a techo y se encuentran plegados formando un anticlinal asimétrico. Desde la base de la Formación Loncoche (Campaniano superior-?Maastrichtiano inferior) hasta los niveles superiores de la suprayente Formación Jagüel (Maastrichtiano superior), el registro de vertebrados e invertebrados fósiles, como así también los análisis sedimentológicos, muestran una progresiva influencia marina vinculada con una ingresión procedente del Atlántico. Los dientes encontrados se asignan a los géneros Squalicorax Whitley y Serratolamna Landemaine (Elasmobranchii, Lamniformes). El género Squalicorax es típico del Cretácico Superior y no se conoce en el Cenozoico. Las facies portadoras de los dientes son margas y pelitas gris amarillentas. El estudio palinológico de cinco niveles de estas facies dio como resultado una asociación dominada casi exclusivamente por ficomas de algas prasinofíceas principalmente pertenecientes a los géneros: Pterospermella Eisenack, Cymatiosphaera Wetzel ex Deflandre y Tasmanites Newton, junto a escasos quistes de dinoflagelados y ausencia de palinomorfos terrestres. Estas algas son más frecuentes en ambientes marinos de reducida salinidad, como la zona proximal de plataforma y son abundantes en aguas preferentemente frías. El hallazgo aquí descripto amplía el escaso registro de condrictios del Cretácico de América del Sur austral y confirma el carácter marino de estas facies, lo que es congruente con el registro palinológico.Sesiones libresFacultad de Ciencias Naturales y Muse

A basal lithostrotian titanosaur (Dinosauria: Sauropoda) with a complete skull: Implications for the evolution and paleobiology of titanosauria

We describe Sarmientosaurus musacchioi gen. et sp. nov., a titanosaurian sauropod dinosaur from the Upper Cretaceous (Cenomanian - Turonian) Lower Member of the Bajo Barreal Formation of southern Chubut Province in central Patagonia, Argentina. The holotypic and only known specimen consists of an articulated, virtually complete skull and part of the cranial and middle cervical series. Sarmientosaurus exhibits the following distinctive features that we interpret as autapomorphies: (1) maximum diameter of orbit nearly 40% rostrocaudal length of cranium; (2) complex maxilla - lacrimal articulation, in which the lacrimal clasps the ascending ramus of the maxilla; (3) medial edge of caudal sector of maxillary ascending ramus bordering bony nasal aperture with low but distinct ridge; (4) ´tongue-like´ ventral process of quadratojugal that overlaps quadrate caudally; (5) separate foramina for all three branches of the trigeminal nerve; (6) absence of median venous canal connecting infundibular region to ventral part of brainstem; (7) subvertical premaxillary, procumbent maxillary, and recumbent dentary teeth; (8) cervical vertebrae with ´strut-like´ centroprezygapophyseal laminae; (9) extremely elongate and slender ossified tendon positioned ventrolateral to cervical vertebrae and ribs. The cranial endocast of Sarmientosaurus preserves some of the most complete information obtained to date regarding the brain and sensory systems of sauropods. Phylogenetic analysis recovers the new taxon as a basal member of Lithostrotia, as the most plesiomorphic titanosaurian to be preserved with a complete skull. Sarmientosaurus provides a wealth of new cranial evidence that reaffirms the close relationship of titanosaurs to Brachiosauridae. Moreover, the presence of the relatively derived lithostrotian Tapuiasaurus in Aptian deposits indicates that the new Patagonian genus represents a ´ghost lineage´ with a comparatively plesiomorphic craniodental form, the evolutionary history of which is missing for at least 13 million years of the Cretaceous. The skull anatomy of Sarmientosaurus suggests that multiple titanosaurian species with dissimilar cranial structures coexisted in the early Late Cretaceous of southern South America. Furthermore, the new taxon possesses a number of distinctive morphologies - such as the ossified cervical tendon, extremely pneumatized cervical vertebrae, and a habitually downward- facing snout - that have rarely, if ever, been documented in other titanosaurs, thus broadening our understanding of the anatomical diversity of this remarkable sauropod clade. The latter two features were convergently acquired by at least one penecontemporaneous diplodocoid, and may represent mutual specializations for consuming low-growing vegetation.Fil: Martínez, Rubén Darío. Universidad Nacional de la Patagonia; ArgentinaFil: Lamanna, Matthew C.. Carnegie Museum Of Natural History; Estados UnidosFil: Novas, Fernando Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "bernardino Rivadavia"; ArgentinaFil: Ridgely, Ryan C.. Ohio University College Of Osteopathic Medicine; Estados UnidosFil: Casal, Gabriel. Universidad Nacional de la Patagonia; ArgentinaFil: Martínez, Javier E.. Hospital Regional de Comodoro Rivadavia; ArgentinaFil: Vita, Javier R.. Resonancia Magnética Borelli; ArgentinaFil: Witmer, Lawrence M.. Ohio University College Of Osteopathic Medicine; Estados Unido

A Nomenclature for Vertebral Fossae in Sauropods and Other Saurischian Dinosaurs

The axial skeleton of extinct saurischian dinosaurs (i.e., theropods, sauropodomorphs), like living birds, was pneumatized by epithelial outpocketings of the respiratory system. Pneumatic signatures in the vertebral column of fossil saurischians include complex branching chambers within the bone (internal pneumaticity) and large chambers visible externally that are bounded by neural arch laminae (external pneumaticity). Although general aspects of internal pneumaticity are synapomorphic for saurischian subgroups, the individual internal pneumatic spaces cannot be homologized across species or even along the vertebral column, due to their variability and absence of topographical landmarks. External pneumatic structures, in contrast, are defined by ready topological landmarks (vertebral laminae), but no consistent nomenclatural system exists. This deficiency has fostered confusion and limited their use as character data in phylogenetic analysis.We present a simple system for naming external neural arch fossae that parallels the one developed for the vertebral laminae that bound them. The nomenclatural system identifies fossae by pointing to reference landmarks (e.g., neural spine, centrum, costal articulations, zygapophyses). We standardize the naming process by creating tripartite names from “primary landmarks,” which form the zygodiapophyseal table, “secondary landmarks,” which orient with respect to that table, and “tertiary landmarks,” which further delineate a given fossa.The proposed nomenclatural system for lamina-bounded fossae adds clarity to descriptions of complex vertebrae and allows these structures to be sourced as character data for phylogenetic analyses. These anatomical terms denote potentially homologous pneumatic structures within Saurischia, but they could be applied to any vertebrate with vertebral laminae that enclose spaces, regardless of their developmental origin or phylogenetic distribution

Paleobiology of titanosaurs: reproduction, development, histology, pneumaticity, locomotion and neuroanatomy from the South American fossil record

Fil: García, Rodolfo A.. Instituto de Investigación en Paleobiología y Geología. Museo Provincial Carlos Ameghino. Cipolletti; ArgentinaFil: Salgado, Leonardo. Instituto de Investigación en Paleobiología y Geología. General Roca. Río Negro; ArgentinaFil: Fernández, Mariela. Inibioma-Centro Regional Universitario Bariloche. Bariloche. Río Negro; ArgentinaFil: Cerda, Ignacio A.. Instituto de Investigación en Paleobiología y Geología. Museo Provincial Carlos Ameghino. Cipolletti; ArgentinaFil: Carabajal, Ariana Paulina. Museo Carmen Funes. Plaza Huincul. Neuquén; ArgentinaFil: Otero, Alejandro. Museo de La Plata. Universidad Nacional de La Plata; ArgentinaFil: Coria, Rodolfo A.. Instituto de Paleobiología y Geología. Universidad Nacional de Río Negro. Neuquén; ArgentinaFil: Fiorelli, Lucas E.. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica. Anillaco. La Rioja; Argentin

Supplemental Information 5: Detail of the excavation of the scapula MDS-OTII,14.

The sauropod of El Oterillo II is a specimen that was excavated from the Castrillo de la Reina Formation (Burgos, Spain), late Barremian–early Aptian, in the 2000s but initially remained undescribed. A tooth and elements of the axial skeleton, and the scapular and pelvic girdle, represent it. It is one of the most complete titanosauriform sauropods from the Early Cretaceous of Europe and presents an opportunity to deepen our understanding of the radiation of this clade in the Early Cretaceous and study the paleobiogeographical relationships of Iberia with Gondwana and with other parts of Laurasia. The late Barremian–early Aptian is the time interval in the Cretaceous with the greatest diversity of sauropod taxa described in Iberia: two titanosauriforms, Tastavinsaurus and Europatitan; and a rebbachisaurid, Demandasaurus. The new sauropod Europatitan eastwoodi n. gen. n. sp. presents a series of autapomorphic characters in the presacral vertebrae and scapula that distinguish it from the other sauropods of the Early Cretaceous of Iberia. Our phylogenetic study locates Europatitan as the basalmost member of the Somphospondyli, clearly differentiated from other clades such as Brachiosauridae and Titanosauria, and distantly related to the contemporaneous Tastavinsaurus. Europatitan could be a representative of a Eurogondwanan fauna like Demandasaurus, the other sauropod described from the Castrillo de la Reina Formation. The presence of a sauropod fauna with marked Gondwananan affinities in the Aptian of Iberia reinforces the idea of faunal exchanges between this continental masses during the Early Cretaceous. Further specimens and more detailed analysis are needed to elucidate if this Aptian fauna is caused by the presence of previously unnoticed Aptian land bridges, or it represents a relict fauna from an earlier dispersal event

Speeds and stance of titanosaur sauropods: analysis of Titanopodus tracks from the Late Cretaceous of Mendoza, Argentina

Speed estimations from trackways of Titanopodus mendozensis González Riga and Calvo provide information about the locomotion of titanosaurian sauropods that lived in South America during the Late Cretaceous. Titanopodus ichnites were found at Agua del Choique, a newly discovered track site in the Loncoche Formation, Late Campanian-Early Maastrichtian of Mendoza, Argentina. This speed study follows the hypothesis of dynamic similarity proposed by Alexander. As a refinement of this method, a complementary equation is presented here based on an articulated titanosaurian specimen collected in strata that are regarded as correlative to those that have yielded Titanopodus tracks (Allen Formation, Neuquén Basin). This analysis indicates that hip height can be estimated as 4.586 times the length of the pes track in derived titanosaurs. With an estimation of the hip height and the stride measurements, the speed is calculated. The study of two wide-gauge trackways indicates that Titanopodus ichnites were produced by mediumsized titanosaurs (hip height of 211-229 cm) that walked at 4.7-4.9 km/h towards the south and southwest, following, in part, a sinuous pathway. These speeds and some taphonomic features of tracks (prominent rims, distorted elongated shapes)indicate the capacity of derived titanosaurs for walking effectively over a very wet and slippery substrate. In the ichnological record, the walking speeds of Titanopodustrackmakers are somewhat faster than those previously inferred for most sauropods.Estimativas de velocidade a partir de trilhas de Titanopodus mendozensis González Riga e Calvo fornecem informações a respeito da locomoção de saurópodes titanossaurianos que viveram na América do Sul durante o Cretáceo Superior.Icnitos de Titanopodus foram encontrados em Agua del Choique, sendo este um sítio de pegadas recentemente descoberto na Formação Loncoche, Campaniano Superior-Maastrichiano Inferior de Mendonza, Argentina. Este estudo de velocidade segue a hipótese de similaridade dinâmica proposta por Alexander. Como um refinamento deste método, uma equação complementar é aqui apresentada tomando como base um espécime titanossauriano articulado coletado em estratos que são tidos como correlativos àqueles que forneceram as pegadas de Titanopodus (Formação Allen, Bacia Neuquén). Esta análise indica que a altura da bacia pode ser estimada como tendo 4,586 vezes o comprimento da pegada do pé em titanossauros derivados. A velocidade é calculada com uma estimativa da altura da bacia e as medidas da passada. O estudo de duas trilhas de medidas amplas indica que os icnitos de Titanopodus foram produzidos por titanossauros de tamanho mediano (altura da bacia de 211-229 cm) que caminhavam a 4,7-4,9 km/hem direção ao sul e sudeste, seguindo, em parte, um caminho sinuoso. Estas velocidades e algumas características tafonômicas das pegadas (margens proeminentes, formatos alongados distorcidos) apontam para a capacidade de titanossauros derivados de caminhar efetivamente sobre um substrato muito úmido e escorregadio. No registro icnológico, as velocidades de caminhada dos geradores de Titanopodus são um pouco mais rápidas do que aquelas previamente inferidas para a maioriados saurópodes