Papers by Leonardo Salgado
Salgado, Leonardo, Gasparini, Zulma (2006): Reappraisal of an ankylosaurian dinosaur from the Upp... more Salgado, Leonardo, Gasparini, Zulma (2006): Reappraisal of an ankylosaurian dinosaur from the Upper Cretaceous of James Ross Island (Antarctica). Geodiversitas 28 (1): 119-135
Exceptionally well−preserved embryonic skulls of Upper Cretaceous (Campanian Anacleto Formation) ... more Exceptionally well−preserved embryonic skulls of Upper Cretaceous (Campanian Anacleto Formation) sauropods from Auca Mahuevo (Neuquén Province, Argentina) provide important insights into the ontogeny and evolution of titanosaurian neosauropods. The most important cranial modifications occurring during titanosaurian ontogeny appear to be centered on the infraorbital and narial regions, which exhibit a substantial degree of “mosaic ” evolution. On one hand, the Auca Mahuevo embryos show a large jugal that forms part of the lower margin of the skull and unretracted external nares, as indi− cated by the position and orientation of the lacrimals as well as the anterior extension of the frontals. Both of these features are ancestral for neosauropods, being present in prosauropods. On the other hand, the embryonic skull exhibits a large ven− tral notch, tentatively interpreted as homologous to the neosauropod preantorbital fenestra, that opens ventral to the jugal and between the maxilla a...
Ameghiniana, 2007
Resumen. Los huesos de dos plesiosaurios elamosauridos (uno subadulto y otro adulto) del Cretacic... more Resumen. Los huesos de dos plesiosaurios elamosauridos (uno subadulto y otro adulto) del Cretacico Superior de Patagonia (Argentina), y los de un mosasaurio adulto del Cretacico Superior de Antartida, son descriptos histologicamente, con el objeto de obtener informacion relacionada con su estilo de vida. Los huesos del elasmosaurido subadulto de Lago Pellegrini (Rio Negro, Argentina), muestran una compactacion endosteal bien desarrollada u osteosclerosis, siendo mayor el grado de desarrollo de este tejido en la vertebra que en el humero o en la cintura pelvica. Por el contrario, los huesos del elasmosaurido analizado (cf. Mauisaurus del area de Salinas de Trapalco, Rio Negro), muestran vacuidades internas que suponen un aligeramiento del hueso (estructura osea de tipo-osteoporotica). La distribucion de la estructura osea osteosclerotica en plesiosaurios juveniles y osteoporotica en adultos es similar a la descripta en plesiosaurios de Nueva Zelanda, y podria encontrarse relacionada ...
Geologica Acta, 2011
This paper presents a new titanosaur sauropod, collected from levels of reddish clays assigned to... more This paper presents a new titanosaur sauropod, collected from levels of reddish clays assigned to the Plottier Formation (Coniacian-Santonian). The holotype of Petrobrasaurus puestohernandezi gen. et. sp. nov. is a disarticulated specimen, from which teeth, cervical, dorsal and caudal vertebrae, sternal plates, metacarpals, femora, tibia, a fragment of ilium, pubis, haemal arches, and cervical and dorsal ribs have been preserved. This period is of particular interest because it saw the definitive isolation of the vertebrate faunas of Patagonia, with the separation of South America from the rest of Gondwana, a process that had begun during the Early Cretaceous. Although some of the characters observed in Petrobrasaurus gen. nov. suggest a relationship with the South American clade Lognkosauria, this new sauropod is regarded as Titanosauria incertae sedis until a more profound analysis of the Titanosauria that in which it is included is undertaken.
Acta Palaeontologica Polonica, 2021
The discovery of theropod shed teeth associated with sauropod remains is relatively common in Cre... more The discovery of theropod shed teeth associated with sauropod remains is relatively common in Cretaceous deposits of Patagonia. However, only a handful of studies have thoroughly explored the phylogenetic affinities of the theropod dental material. Here, we describe and identify twelve theropod shed teeth associated with a partially complete skeleton of a titanosaur sauropod from the Allen Formation (middle Campanian-lower Maastrichtian; Upper Cretaceous) of Paso Córdoba, Río Negro, Argentina. Using three methods, namely a cladistic analysis performed on a dentition-based data matrix, and a discriminant and cluster analyses conducted on a large dataset of theropod teeth measurements, we identify three dental morphotypes which are confidently referred to abelisaurid theropods. Whether the morphotypes represent different abelisaurid subclades or different positional entities within the jaw of the same abelisaurid species, is unknown. Such an identification, nevertheless, provides additional evidence of abelisaurids feeding on sauropod carcasses. This study highlights the importance of using combined qualitative and quantitative methodologies to identify isolated theropod teeth, especially those that can provide direct information on feeding ecology.
Ameghiniana, 2007
Resumen. Se describe el basicraneo de un dinosaurio sauropodo, proveniente del Cretacico Superior... more Resumen. Se describe el basicraneo de un dinosaurio sauropodo, proveniente del Cretacico Superior de Rio Negro, Argentina. El material se asigna al clado Titanosauria, y se discuten algunos caracteres que recuerdan la condicion presente en el genero Antarctosaurus tales como frontales y parietales cortos y anchos, protuberancia supraoccipital sin un surco medial, fenestra supratemporal reducida y orientada dorsalmente, frontales fusionados en la linea media y presencia de una sola prominencia medial interfrontal. Estos caracteres no son diagnosticos y se encuentran en otros titanosaurios como Rapetosaurus, Nemegtosaurus, Saltasaurus y Bonatitan. El basicraneo, aunque incompleto, esta bien preservado permitiendo el examen de ciertas estructuras internas delicadas, como el oido interno que ha quedado expuesto a traves de fracturas. El oido interno de un titanosaurio es aqui descrito por primera vez; este es morfologicamente similar al de otros sauropodos como Diplodocus y Brachiosauru...
Ameghiniana, 2018
Jaw musculature and biomechanical analysis suggest high bite force and scavenger feeding habits f... more Jaw musculature and biomechanical analysis suggest high bite force and scavenger feeding habits for ornithosuchids. Cupressaceae and Podocarpaceae in a diverse assemblage of conifers and bennettitales from the Early Cretaceous of India.
In this paper we describe the only specimens of sauropod dinosaur known in the Rayoso Formation (... more In this paper we describe the only specimens of sauropod dinosaur known in the Rayoso Formation (Albian, Patagonia, Argentina). We found a partially articulated adult specimen and remains of two juveniles in the same site. The adult is represented by most of the skull, neck and much of tail articulated. The juvenile specimens retain much of the appendicular skeleton and scapula, high systematic importance. The morphological features of the teeth, caudal vertebrae and scapula place the collected specimens among the rebbachisaurids, though with clear differences with other taxa described for the Lower Cretaceous of Argentina, so it could be a new species.
Acta Palaeontologica Polonica, 2005
Exceptionally well−preserved embryonic skulls of Upper Cretaceous (Campanian Anacleto Formation) ... more Exceptionally well−preserved embryonic skulls of Upper Cretaceous (Campanian Anacleto Formation) sauropods from Auca Mahuevo (Neuquén Province, Argentina) provide important insights into the ontogeny and evolution of titanosaurian neosauropods. The most important cranial modifications occurring during titanosaurian ontogeny appear to be centered on the infraorbital and narial regions, which exhibit a substantial degree of “mosaic” evolution. On one hand, the Auca Mahuevo embryos show a large jugal that forms part of the lower margin of the skull and unretracted external nares, as indi− cated by the position and orientation of the lacrimals as well as the anterior extension of the frontals. Both of these features are ancestral for neosauropods, being present in prosauropods. On the other hand, the embryonic skull exhibits a large ven− tral notch, tentatively interpreted as homologous to the neosauropod preantorbital fenestra, that opens ventral to the jugal and between the maxilla an...
THE GENUS AEOLOSAURUS (SAUROPODA, TITANOSAURIDAE) IN THE ALLEN FORMATION (CAMPANIAN-MAASTRICHTIAN... more THE GENUS AEOLOSAURUS (SAUROPODA, TITANOSAURIDAE) IN THE ALLEN FORMATION (CAMPANIAN-MAASTRICHTIAN) OF RIO NEGRO PROVINCE, ARGENTINA. Remains assigned to Aeolosaurus Powell, 1986 from the Allen Formation are described. The specimen differs from the holotype of Aeolosaurus rionegrinus Powell, 1986 in the length of the prezigapophyses, relative position of the postzigapophyses, and radius and ischium morphology. Considerations on a specimen tentatively assigned to the type species, and modified diagnosis of genus are included. Association of dermal plates to the specimen here described is commented.
Resumen. Se describen vertebras de un plesiosaurio halladas en la Formacion Allen (Campaniano tar... more Resumen. Se describen vertebras de un plesiosaurio halladas en la Formacion Allen (Campaniano tardio Maastrichtiano temprano; Cretacico Superior), en la localidad de Loma Puntuda, Salitral de Santa Rosa, Provincia de Rio Negro, Argentina. Una serie de caracteristicas anatomicas, tales como los centros vertebrales anficelicos mas altos que largos, la presencia de un anillo rodeando la cara articular posterior de las vertebras cervicales, la existencia de una quilla ventral en las vertebras cervicales, las espinas neurales cervicales expandidas distalmente y posiblemente inclinadas hacia atras, asi como las caras laterales de los cuerpos dorsales fuertemente comprimidas, justifican la asignacion a los Polycotylidae, un grupo de plesiosauroideos de cuello corto relativamente comun en el Cretacico Superior de Norteamerica. Este es el primer hallazgo de restos postcraneanos de un policotilido en Sudamerica, en donde estos plesiosaurios eran conocidos hasta hoy a partir de fragmentos cran...
Spanish Journal of Palaeontology
Ameghiniana
This taxon was only briefly described when it was named and most of its originally proposed autap... more This taxon was only briefly described when it was named and most of its originally proposed autapomorphies are now recognized as having a more widespread distribution amongst titanosaurs. Herein we present a detailed osteological description of the axial skeleton, and revised diagnosis for this taxon that firmly establish its validity. Based on comparisons with other titanosaurs, we found three new possible autapomorphies for the axial skeleton of Rinconsaurus, which added to its original combination of characters, endorsing this taxon as a valid genus. Besides, this revision of Rinconsaurus provides additional osteological data that will contribute to a better resolution of titanosaur phylogeny, contributing at the same time to our understanding of the clade Rinconsauria.
Revista del Museo Argentino de Ciencias Naturales
The first fossil remains of vertebrates, invertebrates, plants and palynomorphs of the Chorrillo ... more The first fossil remains of vertebrates, invertebrates, plants and palynomorphs of the Chorrillo Formation (Austral Basin), about 30km to the SW of the town of El Calafate (Province of Santa Cruz), are described. Fossils include the elasmarian (basal Iguanodontia) Isasicursor santacrucensis gen. et sp. nov., the large titanosaur Nullotitan glaciaris gen. et sp. nov., both large and small Megaraptoridae indet., and fragments of sauropod and theropod eggshells. The list of vertebrates is also composed by the Neognathae Kookne yeutensis gen. et sp. nov., two isolated caudal vertebrae of Mammalia indet., and isolated teeth of a large mosasaur. Remains of fishes, anurans, turtles, and snakes are represented by fragmentary material of low taxonomical value, with the exception of remains belonging to Calyptocephalellidae. On the other hand, a remarkable diversity of terrestrial and freshwater gastropods has been documented, as well as fossil woods and palinological assemblages. The Chorrillo Formation continues south, in the Las Chinas River valley, southern Chile, where it is called Dorotea Formation. Both units share in their lower two thirds abundant materials of titanosaurs, whose remains cease to appear in the upper third, registering only elasmarians (Chorrillo Formation) and hadrosaurs (Dorotea Formation). Above both units there are levels with remains of invertebrates and marine reptiles. It is striking that the dinosaurs of the lower two thirds of the Chorrillo and Dorotea formations are represented by large basal titanosaurs and Megaraptoridae coelurosaurs, being the Saltasaurinae and Aeolosaurinae sauropods and Abelisauridae theropods totally absent. In contrast, these taxa are dominant components in sedimentary units of central and northern Patagonia (e.g., Allen, Los Alamitos, La Colonia formations). Such differences could reflect, in part, a greater antiquity (i.e., late Campanian-early Maastrichtian) for the Chorrillo fossils, or, more probably, different environmental conditions. Thus, knowledge of the biota of the southern tip of Patagonia is expanded, particularly those temporarily close to the K-Pg boundary.
Acta Palaeontologica Polonica
Rebbachisaurids are a group of basal diplodocimorph sauropods that diversified in Gondwana at the... more Rebbachisaurids are a group of basal diplodocimorph sauropods that diversified in Gondwana at the end of the Early Cretaceous and the beginning of the Late Cretaceous. It is a group of great palaeobiogeographical interest, for it clearly illustrates various processes of dispersal throughout Gondwana and to Laurasia prior to the breakup of Africa and South America. However, the relationships within the group are still under discussion owing to the scarcity of cranial material that would help clarify them. In the present paper we describe the new rebbachisaurid Lavocatisaurus agrioensis gen. et sp. nov. from the Aptian-Albian (Lower Cretaceous) of Neuquén (Argentina). Remains have been recovered belonging to an adult specimen (holotype) and two immature specimens (paratypes). Taken together, almost all the bones of the taxon are represented, including most of the cranium. Lavocatisaurus agrioensis gen. et sp. nov. is the first rebbachisaurid from Argentina with an almost complete cranium, making it possible to recognize differences with respect to other rebbachisaurids, such as the highly derived Nigersaurus. Among its most notable characters are the presences of a large preantorbital fenestra and maxillary teeth that are significantly larger than those of the dentary. Our phylogenetic study places Lavocatisaurus amongst basal rebbachisaurids, as the sister lineage to Khebbashia (the clade formed by Limaysaurinae + Rebbachisaurinae). This position, which is somewhat more derived than that previously suggested for Comahuesaurus and Zapalasaurus (the Argentinean rebbachisaurids closest in geographical and geological terms), reaffirms the presence of different basal rebbachisaurid lineages in the Early Cretaceous of Patagonia.
Palaeogeography, Palaeoclimatology, Palaeoecology
Abstract Histological studies have proven to be a powerful tool for addressing sauropod paleobiol... more Abstract Histological studies have proven to be a powerful tool for addressing sauropod paleobiology, with most focus on adult and subadult individuals. The aim of this study is to describe long bone histology (femur) in early juvenile titanosaur sauropods, to expand our knowledge about early stages of development. The material consists of two small femora of indeterminate titanosaurs from the Upper Cretaceous Bajo de la Carpa and Allen formations of Argentina. Both femora from juvenile specimens show predominant fibrolamellar bone tissue with plexiform vascularization pattern, suggesting a fast growth rate. Despite the early stage of development of the studied specimens, secondary remodelling is evident in one of them. In the other sample, a growth mark is observed, which suggests unexpected cyclical growth and a possible departure from the typical growth strategy of sauropod dinosaurs. In addition, we examine indeterminate long bones of titanosaur embryos from the Anacleto Formation of Argentina. The embryos shows poor development of cortical bone, high density of large simple canals and presence of Kastschenko's line suggest that these individuals died during an early stage of ossification. This study reveals that the early growth of at least some titanosaurs departs from the reported in neosauropod dinosaurs.
En este trabajo se discute la biología de los titanosáuridos (Sauropoda), tomando como referencia... more En este trabajo se discute la biología de los titanosáuridos (Sauropoda), tomando como referencia principalmente su histología ósea y la biología de la reproducción. La evolución del grupo es abordada teniendo como marco los resultados obtenidos en un análisis filogenético de caracteres. Los titanosáuridos son defínidos como titanosaurios más relacionados a Saltasaurus que a Andesaurus. Los caracteres que diagnostican a este grupo son: caudales anteriores y medias con láminas pre y postespinales; ulna con proceso olécranon prominente; seis vértebras sacras; ausencia de hipósfeno-hipantro en las vértebras dorsales posteriores; caudales medias y posteriores procélicas; placas estemalesde contorno semilunar; falanges de la mano ausentes; lóbulo preacetabular del ileón casi horizontal y fuértemente proyectado hacia afuera. Dentro de los titanosáuridos, Titanosaurus colberti y los Opisthocoelisacralia (N.Taxon) presentan las siguientes sinapornorfias: lámina prespinal formada hasta la ba...
Zootaxa
A new Late Cretaceous titanosaurian sauropod from the Sierra Barrosa locality (Anacleto Formation... more A new Late Cretaceous titanosaurian sauropod from the Sierra Barrosa locality (Anacleto Formation, Late Cretaceous, early Campanian) of Neuquén Province, Argentina, Barrosasaurus casamiquelai gen. et sp. nov., is described. The holotype of this species consists of three large and incomplete, although well-preserved, dorsal vertebrae (one probably the third, the next the seventh or eighth, and the last the ninth or tenth). The arrangement of neural arch laminae in the dorsal vertebrae of this titanosaur differs from that present in other genera in the following ways: the spinoprezygapophyseal laminae are well developed in the third vertebra, and relictual in the seventh or eighth vertebra; two spinodiapophyseal laminae are present in the seventh or eighth and in the ninth or tenth vertebrae, the anterior spinodiapophyseal lamina being more strongly developed than the posterior spinodiapophyseal lamina in the ninth or tenth vertebra. These characters, among others, allow the recogniti...
revista PH
El área natural protegida Paso Córdoba, creada por ordenanza 2583 de septiembre de 1997, posee un... more El área natural protegida Paso Córdoba, creada por ordenanza 2583 de septiembre de 1997, posee unas 17.000 ha de superficie. Allí afloran sedimentos del Cretácico Superior y del Mioceno-Plioceno. l área posee varios puntos de especial interés geológico y paleontológico, entre ellos, los llamados valles de la luna Rojo (Cretácico) y Amarillo (Mio-Plioceno). Originalmente, el objeto de conservación era el ambiente natural (art. 1 de la ordenanza 2583). Sin embargo, con el correr de los años, y a raíz de las investigaciones paleontológicas llevadas a cabo por distintos grupos de investigación, lo paleontológico fue tomando un mayor relieve entre los objetivos de conservación
Cretaceous Research
The Paso C ordoba fossiliferous site (Río Negro, Northern Patagonia) is one of the first Mesozoic... more The Paso C ordoba fossiliferous site (Río Negro, Northern Patagonia) is one of the first Mesozoic fossiliferous localities studied in Argentina. There, turtle, crocodile and dinosaur remains as well as dinosaur and bird tracks have been recorded. Recently, a new locality with vertebrate tracks, the Cañad on del Desvío, has been discovered in Paso C ordoba. Six track-bearing layers were located in outcrops belonging to the Anacleto (lower to middle Campanian, Neuqu en Group) and Allen (middle Campanian-lower Maastrichtian, Malargüe Group) formations. The Cañad on del Desvío locality reveals that vertebrate trace fossils are distributed in two distinct environments, floodplains of a meandering fluvial to shallow lacustrine system and a wet interdune deposit that is associated to an aeolian setting. Also, in the logged section several soft sediment deformation structures were found. In regard of this, a sedimentary facies analysis is provided in order to assess the palaeoenvironmental implications of this new record. The analysed tracks are preserved in cross-sections, on bedding-planes and as natural casts. When it is possible, the tracking surface, true tracks, undertracks and overtracks/natural casts have been identified and the track preservation and the formation history of the tracksite are discussed. Only two tracks preserve enough anatomical details to relate them with their trackmakers, in this case hadrosaurid dinosaurs. The stratigraphical, facial and palaeoenvironmental data of this study support the idea of a transitional passage between the Anacleto and Allen Formation in Paso C ordoba. The presence of hadrosaurid dinosaur tracks suggests that the upper part of the log, where this kind of tracks were found, likely belong to Allen Formation due to this dinosaurs appear in the Southern Hemisphere in this epoch. The sum of osteological and ichnological remains improve the Paso C ordoba palaeofaunistic knowledge. The presence of six different levels in which the trackmakers walked reflects the abundance of vertebrates in the transition between Anacleto and Allen formations.
Uploads
Papers by Leonardo Salgado