Titanosaurid Sauropods Research Articles

First record of abelisaurid theropods and a peirosaurid crocodyliform from the Upper Cretaceous of Precordillera of La Rioja, NW Argentina

Extra-Patagonian records of Cretaceous theropod dinosaurs in Argentina are limited. When it comes to the Northwest of Argentina, most of the records come from the Cretaceous rocks of Salta Province, which yielded ceratosaurian abelisauroids like Noasaurus and Guemesia. Preliminary studies of the Los Llanos Formation at Eastern La Rioja Province recognized bone remains of Upper Cretaceous undetermined Abelisauridae and Coelurosauria. Recent surveys in the Northwest of the same province, in the outcrops of the Upper Cretaceous Ciénaga del Río Huaco Formation, at Quebrada Santo Domingo (Precordillera), resulted in the discovery of six isolated shed tooth crowns of putative abelisaurid theropods and crocodyliforms. They were found in association with partial skeletons of titanosaurid sauropod dinosaurs from two quarry sites, in the lower and upper sections of the same unit. Here we corroborate the taxonomic assignment of these specimens and their phylogenetic relationships. Five out of six teeth were assigned to Abelisauridae, whereas the remaining is considered to belong to a peirosaurid crocodyliform. Thus, the first occurrence of abelisaurid theropods and peirosaurid crocodyliforms in the Upper Cretaceous of the Precordillera of La Rioja is confirmed. Even though the teeth cannot be assigned to a less inclusive taxon, the difference in their stratigraphic position might indicate the presence of more than a single abelisaurid species in this region. The new results offer an optimistic perspective for future expeditions in this area, which intend to recover more skeletal elements.

What is the most giant sauropod from Argentina? Diversity of large titanosaurs from Patagonia

This work’s intent is to establish which was the most giant titanosaurid sauropod from Argentina. The evidence is scarce; however, we have tried to select the largest bones of the nine most giant titanosaurids. Argentinosaurus has been proposed as the largest titanosaurid, but recently a new king has been erected: the Patagotitan. In this review, we will see that there are some inconsistences and difficulties to define which is the largest. In other words, giant titanosaurids were a group of sauropods with a variable morphology and probably the overall shape was different. Among the largest titanosaurids, we have included Argyrosaurus superbus, Antarctosaurus giganteus, Argentinosaurus huinculensis, Puertasaurus reuili, Futalognkosaurus dukei, Traukutitan eocaudata, Dreadnoughtus schrani, Notocolossus gonzalezparejasi, and Patagotitan mayorum.

Insights into paleoecology of the Bajo Barreal Formation (Upper Cretaceous), Patagonia, Argentina

We present the first integrate paleoecological study which includes both previous and new sedimentological, paleoclimate, fauna and flora analyses in the Bajo Barreal Formation (Upper Cretaceous), Golfo San Jorge Basin, Patagonia, Argentina. The study was carried out principally at the Estancia (=Ranch) Ocho Hermanos Locality, although other significant paleontological localities of the Bajo Barreal Formation are included. In the Estancia Ocho Hermanos Locality, the paleoenvironment is characterized by low sinuosity single-channelized fluvial systems, with well-developed proximal floodplains. Paleoclimate was interpreted as warm and humid with marked seasonality. This locality was dominated by dinosaurs, including sauropods (titanosaurs and rebbachisaurids) and theropods (abelisaurids and megaraptorids), but other vertebrates, such as pterosaurs, crocodyliforms, turtles and fishes were also part of the paleoecosystem. In addition, the first stable isotope analysis on Mesozoic teeth (dinosaurs and crocodyliforms) from the Golfo San Jorge Basin was conducted. This new information revealed different sources of water utilized by theropod and sauropod dinosaurs, allowed to infer preliminary modes of life for crocodyliforms, and provided information about diet of these Mesozoic organisms. Ground-level and mid-height feeding are interpreted for rebbachisaurid and titanosaurid sauropods, respectively. Ferns are considered the main non-arboreal component of this ecosystem and possibly an important source of the diet of sauropods, whereas angiosperms (eudicots and monocots) would have been present as well. On the other hand, gymnosperms, mainly Araucariaceae, and in a minor proportion Podocarpaceae, and Cheirolepidiaceae, would encompass the arboreal component of this environment. Abelisaurids could be recognized as one of the top predators of this paleoecosystem, in part due to their relative abundance, in relation to other carnivores. Finally, in a broad context, this study augments our understanding of Cretaceous terrestrial ecosystems of south-central Patagonia and contributes for future comparisons with other chronologically equivalent localities, principally, from the Southern Hemisphere.

Dinosaur Eggs and Babies in the UNESCO GGN Hateg Country Dinosaurs Geopark (Romania)

In 1898, when the first dinosaur eggs were discovered in Hațeg Country (which in 2005 became part of the UNESCO Global Geopark Network), not one dinosaur egg had ever been unearthed either in the vicinity or anywhere in Romania. Twenty years later, tens of sites bearing remnants of dinosaur eggs – of which at least eight are dinosaur incubation sites – had been mapped in Hațeg Country and across Southern Transylvania as a whole. The most famous is the site at Tuștea, situated in the north-western part of the Hațeg Basin, especially well known because of the so-called “Tuștea Puzzle” whereby spherical megaloolithid eggs, almost universally seen as those of titanosaurid sauropods, are associated with hadrosaurid neonates. Tuștea is the only site in Europe to feature the remains of dinosaur neonates alongside eggs and eggshells from the Upper Cretaceous. Research here and in other areas of the Hațeg Basin highlighted the climates and sedimentology of the areas where the eggs were laid roughly 68–70 million years ago, and revealed aspects of nest building and the behavior of dinosaur neonates after hatching. The site’s scientific importance is strengthened by the great diversity of vertebrate fossil discoveries: frogs, lizards, snakes, saurischian and ornithischian dinosaurs, pterosaurs and mammals – 21 taxa in total, ranking Tuștea among the richest paleontological sites in Europe. After 24 years of continuous research primarily by professors and students from the University of Bucharest, the current owner of the land, making use of legislative inconsistencies governing the right to land ownership, forbade further investigation. During this time, the research site has degraded substantially and today requires urgent restorative and conservation measures lest it be lost forever.

The Late Cretaceous dinosaur track record of Bolivia – Review and perspective

We present an update and a review of the Late Cretaceous dinosaur tracksites of Bolivia. The Puca Group (Coniacian – Late Maastrichtian) records the tracks and trackways of two different titanosaurid sauropods, ankylosaurs, hadrosaurs and different theropod groups from the Central Andean lacustrine back arc basin. We review the sites from the Maragua syncline (Chuquisaca) and present new data on the famous Toro Toro site (Potosi).Furthermore, the first complete map of the world's largest dinosaur tracksite, Cal Orck'o (El Molino Formation, Sucre) gives an insight into behavior and movement patterns. Parallel trackways of subadult ankylosaurs provide the first unequivocal evidence of social behavior amongst these dinosaurs worldwide. The El Molino Formation and the coeval deposits of Southern Peru and Northern Argentina form a megatracksite with a size of around 100,000 km2. The paleogeographic position of the main sites within the basin suggests that they are part of a seasonal migration route along the shoreline and deltas of an ancient lake system.

New lower jaw and teeth referred to Maxakalisaurus topai (Titanosauria: Aeolosaurini) and their implications for the phylogeny of titanosaurid sauropods.

Sauropod dinosaurs compose a diversified, well known, and worldwide distributed clade, with a stereotyped body plan: deep trunk, elongated neck and tail, columnar limbs and very small skull. In Brazil, the group is represented by ten formally described Cretaceous species, mostly titanosaurs. This is the case of Maxakalisaurus topai, known based on an incomplete and disarticulated skeleton, unearthed from deposits of the Adamantina Formation in Minas Gerais. Here, we report a partial right dentary, including five isolated teeth, collected from the same site as the type-series of M. topai and tentatively referred to that taxon. The bone is gently curved medially, the functional teeth are set on an anterolingual position, and two replacement teeth are seen per alveoli. New morphological data gathered from that specimen was employed to conduct a comprehensive phylogenetic analysis of Titanosauria (with 42 taxa and 253 characters), based on previous studies. The Aeolosaurini clade was recovered, with Gondwanatitan and Aelosaurus as sister taxa, and Maxakalisaurus, Panamericansaurus, and Rinconsaurus forming a basal polytomy.

Oxygen and carbon isotope compositions of middle Cretaceous vertebrates from North Africa and Brazil: Ecological and environmental significance

In order to investigate mid-Cretaceous terrestrial climates of low paleolatitudes, Moroccan, Tunisian and Brazilian vertebrate apatites have been analyzed for their oxygen and carbon isotope compositions of phosphates (δ 18O p) and carbonates (δ 18O c, δ 13C c). At each site, coexisting theropod dinosaurs, titanosaurid sauropods, pterosaurs, crocodilians, turtles and fish have distinct δ 18O p and δ 13C c values reflecting their ecologies, diets and foraging environments. Oxygen isotope compositions of surface waters (δ 18O w) estimated from turtle and crocodile δ 18O p values range from − 5.0 ± 1.0‰ to − 2.4 ± 1.0‰, which do not differ from mean annual rainwater values occurring today under inter-tropical sub-arid to arid climates. High water temperatures ranging from 21 ± 6 °C to 34 ± 2 °C deduced from fish δ 18O p values are in agreement with those published for mid-Cretaceous low latitudes. Temporary or seasonal droughts are inferred from high δ 18O p values of lungfish teeth, even though lower reptile δ 18O p values suggest the use of distinct and most likely larger or regularly renewed bodies of water. Environmental conditions of the studied low latitude regions during the Aptian–Cenomanian interval were somewhat similar to those experienced today under semi-arid to arid tropical or equatorial climates, but with higher mean surface temperatures than present-day ones.

Overview of the Late Cretaceous Biota of the western São Paulo State, Brazil, Bauru Group

Abstract The Turonian–Maastrichtian beds of the Bauru Group, western Sao Paulo State (Brazil), have yielded a diverse biota. The nine species of mesoecrocodilians are all mesosuchians. There is a single frog, a Neubatrachia. The vertebrates include, four types of fishes, a neobatrachian frog, an anilioid snake, two lizard, six species of podocnemid turtles, nine species of mesosuchian mesoecrocodilians three theropods, two birds, five titanosaurid sauropods, and one mammalian. The invertebrates include one cyclo, one cyclophoroid and eight pulmonates. Plants are represented by only two carophyte species. The biota from western Sao Paulo State is one the most diverse of the Late Cretaceous in Brazil. The biota from this area confirms that Bauru Group was connected to Patagonia and other Gondwanan areas during the Late Cretaceous.

Los Cayos S y D: dos afloramientos con icnitas de saurópodos, terópodos y ornitópodos en el Cretácico inferior del área de Los Cayos (Cornago, La Rioja, España)

Although most part of the Los Cayos area track-bearing layers have yielded almost non-avian theropod footprints, Los Cayos S and D have revealed the presence of fossil prints belonging to sauropods and ornithopods respectively. Los Cayos S contains ten track-bearing layers, but the most significant one shows a short sauropod trackway that, based on manus print morphology, it is identified with the ichnogenus Titanosaurimanus . This trackway was caused by a titanosaurid sauropod or at least by a titanosauriform. On the contrary, Los Cayos D has yielded abundant footprints —most of them isolated— that have been produced by relatively big ornithopod dinosaurs. We identify these tracks with the ichnogenus Iguanodontipus . The existence of both footprint morphotypes is very interesting for the Los Cayos area due to it represents the presence of large herbivorous dinosaurs in those Cretaceous ecosystems that produced the sediments of the Enciso Group.

THREE‐DIMENSIONAL MODELLING AND ANALYSIS OF DINOSAUR TRACKWAYS

Abstract: Light Detection And Range (LiDAR) imaging provides a means to model the 3D geometry of fossil tracks in the field with high accuracy. This represents a considerable advance for the science of vertebrate ichnology in which traditional field methods suffer from a significant degree of abstraction and lack the resolution required to interpret tracks quantitatively. Three‐dimensional LiDAR models provide additional morphometric information and allow the application of new analytical tools unique to the digital environment. The method will enable fossil track morphometrics to develop into an iterative process that combines 3D visualization and multivariate statistical methods, blending qualitative and quantitative approaches and allowing track morphologies to be compared holistically. Modelling of trackways from Fumanya (south‐east Pyrenees) using LiDAR has enabled variation in linear track dimensions to be explained by the varied contribution of different modes of shear with increasing depth below the foot/sediment interface. Features in the relief of pes traces indicate that subsurface zones within their track volumes are defined by the interaction of puncture and local shear, below a surface zone of liquefaction failure now lost to erosion. This model of mechanical failure enables a preliminary review of the pedal kinematics of titanosaurid sauropod dinosaurs and suggests multiphase loading of the sediment by the titanosaurid pes. However, from inspection of these 3D surfaces alone it is not possible to differentiate between the possibility of one or two discrete phases of pedal motion preceding the toe‐off event at the maximum height of the support phase. By integrating LiDAR models with analogue modelling within a 3D digital environment it will be possible to clarify such interpretations of fossil tracks and the locomotor mechanics of extinct animals.

First abelisaurid bone remains from the Maastrichtian Marília Formation, Bauru Basin, Brazil

Bones of abelisaurid theropods from the Upper Cretaceous (Maastrichtian) Marília Formation, Bauru Basin, Brazil, are here described. They are a dorsal vertebra, the distal part of a femur, and a pedal phalanx corresponding to three specimens found in different fossil sites of Uberaba County, Minas Gerais State. These specimens are the first abelisaurid bones from Uberaba County and thus verify the presence of these theropods, previously indicated only by isolated teeth. The new discoveries, together with that of the abelisaurid Pycnonemosaurus found elsewhere in the Bauru Basin, indicate that these theropods were the most common large predatory dinosaurs in South America during the Cretaceous. The assemblage of abelisaurid theropods and titanosaurid sauropods in the Maastrichtian beds of Brazil is congruent with that documented in same-aged beds of Patagonia.

Description of a sauropod dinosaur braincase (Titanosauridae) from the Late Cretaceous Rio Colorado Subgroup, Patagonia

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.

Eggs of titanosaurid sauropods from the Upper Cretaceous of Auca Mahuevo (Argentina)

We provide a detailed description of the sauropod eggs from the Late Cretaceous nesting site of Auca Mahuevo (Neuquén Province, Argentina), the only eggs that are unequivocally associated with titanosaurid dinosaurs. These eggs are subspherical averaging 132 by 115 mm. Well-preserved specimens display a pronounced eggshell ornamentation that consists mostly of single nodes averaging 0.58 mm in diameter and 0.28 mm in height (base to apex) with internodular values of 0.52 to 0.87 mm. The pore canal network consists of vertical and horizontal canals intersecting at the bases of eggshell units. Vertical canals may fork defining a "Y" pattern and their diameters vary between 0.08 and 0.2 mm. Their surficial apertures of 0.15 to 0.29 mm are funnel like and located between the surficial nodes. In pristine specimens, the eggshell thickness equals 1.31 mm, and radial sections exhibit a single structural horizontal layer composed of juxtaposed shell units consisting of acicular calcite crystals radiating from an organic core. Relying only on taxonomically identified oological material, we regard this character also shared in the innermost layer (layer 1) of Deinonychus antirrhopus, oviraptorid theropods, and observed during an early oogenetic stage in extant bird as primitive for saurischians. The eggshell morphology advocates that these eggs were likely incubated in moist nesting environments, perhaps such as nests covered with vegetal matter. Examination of the South American megaloolithid eggshells reveals that the titanosaurid eggs from Auca Mahuevo are mostly similar to those described as Megaloolithus patagonicus and Megaloolithus pseudomamillare.

Nest Structure for Sauropods: Sedimentary Criteria for Recognition of Dinosaur Nesting Traces

Abstract Six egg-filled depressions discovered in the Upper Cretaceous Anacleto Formation (Campanian) of Patagonia, Argentina, and interpreted as dinosaur nests, provide the only known evidence of titanosaurid sauropod nest construction. These nest trace fossils show truncation of sedimentary structures as well as differences in texture between the host substrate and in-filling sediment. Titanosaurid sauropods excavated and laid eggs in open nests rather than burying clutches in sediment. In addition, this paper establishes criteria for definitive recognition of excavated nests in the stratigraphic record.

A JUVENILE SPECIMEN OF THE SAUROPOD DINOSAUR ALAMOSAURUS SANJUANENSIS FROM THE UPPER CRETACEOUS OF BIG BEND NATIONAL PARK, TEXAS

A juvenile specimen of the titanosaurid sauropod Alamosaurus sanjuanensis, recovered from just below the Cretaceous/Tertiary boundary horizon in Big Bend National Park, Texas, is from an individual less than half the size of adult specimens referred to this species. The disarticulated skeleton was preserved in deposits of a shallow flood-plain pond and includes elements not previously described, allowing for an improved diagnosis for this species. The elongate opisthocoelous cervical vertebrae have non-bifid posteriorly deflected neural spines with deep postspinal fossae. The dorsal vertebrae have wide spatulate neural spines with strong prespinal laminae, and lack hyposphene-hypantrum articulations. Alamosaurus sanjuanensis exhibits a unique morphology of the ischium, evident even in this juvenile specimen. Comparison with other titanosaurid species suggests that A. sanjuanensis is most closely related to an unnamed titanosaur from Peiropolis, Brazil and Neuquensaurus australis from Argentina.

A juvenile specimen of the sauropod dinosaur Alamosaurus sanjuanensis from the Upper Cretaceous of Big Bend National Park, Texas

A juvenile specimen of the titanosaurid sauropod Alamosaurus sanjuanensis, recovered from just below the Cretaceous/Tertiary boundary horizon in Big Bend National Park, Texas, is from an individual less than half the size of adult specimens referred to this species. The disarticulated skeleton was preserved in deposits of a shallow flood-plain pond and includes elements not previously described, allowing for an improved diagnosis for this species. The elongate opisthocoelous cervical vertebrae have non-bifid posteriorly deflected neural spines with deep postspinal fossae. The dorsal vertebrae have wide spatulate neural spines with strong prespinal laminae, and lack hyposphene-hypantrum articulations. Alamosaurus sanjuanensis exhibits a unique morphology of the ischium, evident even in this juvenile specimen. Comparison with other titanosaurid species suggests that A. sanjuanensis is most closely related to an unnamed titanosaur from Peiropolis, Brazil and Neuquensaurus australis from Argentina.

A giant sauropod dinosaur from an Upper Cretaceous mangrove deposit in Egypt.

We describe a giant titanosaurid sauropod dinosaur discovered in coastal deposits in the Upper Cretaceous Bahariya Formation of Egypt, a unit that has produced three Tyrannosaurus-sized theropods and numerous other vertebrate taxa. Paralititan stromeri is the first tetrapod reported from Bahariya since 1935. Its 1.69-meter-long humerus is longer than that of any known Cretaceous sauropod. The autochthonous scavenged skeleton was preserved in mangrove deposits, raising the possibility that titanosaurids and their predators habitually entered such environments.

The smallest of the largest: a new look at possible dwarfing in sauropod dinosaurs

Franz Baron Nopcsa recognised that the Late Cretaceous titanosaurid sauropod from Transylvania, Magyarosaurus dacus, was much smaller than the better known sauropods from the Upper Jurassic of the United States and even from Late Cretaceous deposits elsewhere in the world. In keeping with his biogeographic interpretations, Nopcsa viewed this difference as a consequence of body-size effects via island habitation. We present a preliminary re-evaluation of Nopcsa's claims and their heterochronic consequences using two approaches, viz. (1) regression analysis of humeral data as a means of establishing patterns in body size among titanosaurids, and (2) optimisation of humeral data onto titanosaurid cladograms to evaluate evolutionary trends within the clade. Our regression analysis is based on twenty species distributed among fourteen genera of neosauropods and uses length and mid-shaft mediolateral width of the humerus of presumed fully adult forms, and of growth samples that consist of postnatal to adult individuals. Linear regression analysis suggests that, among adult neosauropods, M. dacus appears to be represented by the smallest individuals; that M. dacus humeri appear to be more similar to those of subadults than to adults of other taxa; and that this ‘juvenile’ morphology may constitute dwarfing in M. dacus by paedomorphosis. In order for these regressions to reflect their evolutionary context more fully, we also present optimisation analyses of humeral form within Titanosauroidea. Although many aspects of the phylogeny of this clade are relatively poorly resolved, preliminary results of our analyses are consistent with the conclusion that M. dacus was a heterochronic dwarf.

Titanosaurid (Sauropoda) osteoderms from the Late Cretaceous of Madagascar

ABSTRACT In 1896 Charles Depéret described a fauna of dinosaurs from the Upper Cretaceous (?Campanian) Maevarano Formation from the Mahajanga Basin of northwest Madagascar. Among the dinosaurs was a titanosaurid sauropod that he named Titanosaurus madagascariensis. He attributed to the titanosaurid a large, thick circular osteoderm. His referral of an osteoderm to a sauropod was widely doubted until 1980 when Bonaparte and Powell described Saltasaurus loricatus, an armored titanosaurid from Argentina. Since then titanosaurid osteoderms have been recognized from Spain, France and Malawi. In 1996, we collected three isolated and eight associated osteoderms from the Maevarano Formation, confirming Depéret's prescient observation. They range in length from 3 cm to 17 cm, and in thickness up to 6.5 cm. At least one of the two titanosaurids we now recognize from Madagascar was covered with a sparse armor, and that the skin was in places nearly 7 cm thick.

The last stages of dinosaur faunal history in Europe: a succession of Maastrichtian dinosaur assemblages from the Corbières (southern France)

AbstractWe report the discovery of a dinosaur assemblage in the non-marine Late Maastrichtian of the Corbieres region of southern France; this allows the reconstruction of the succession of dinosaur faunas during the Maastrichtian in western Europe. An Early Maastrichtian fauna dominated by titanosaurid sauropods was replaced by a Late Maastrichtian assemblage dominated by hadrosaurs. This important faunal replacement seems to coincide with environmental changes (documented by sedimentological and palynological evidence) which have been linked to a marine regression during the Maastrichtian. This suggests that sea-level changes influenced the evolution of dinosaur faunas in Europe during the Late Cretaceous, but were not sufficient to cause the final extinction of dinosaurs, for which other causes must be sought.