Amargatitanis macni is Really a Dicraeosaurid Sauropod

Reappraisal of the Early Cretaceous sauropod dinosaur Amargatitanis macni (Apesteguía, 2007), from northwestern Patagonia, Argentina

Authors:

Gallina et al

Abstract:

Amargatitanis macni Apesteguía, 2007 was described as a purported titanosaur sauropod. That referral is significant because Amargatitanis would represent one of the oldest known members of Titanosauria. However, this referral and even the systematic validity of the taxon were questioned. Here, all the available remains of the taxon are evaluated including a description of unpublished elements. The identity of the type material is discussed based on a first-hand examination of the specimens and evaluation of the original field notes as reliable evidence for bone association. The original holotype of Amargatitanis is a chimaera, as pointed out by previous authors. Herein a new, modified holotype for Amargatitanis is proposed. This analysis presents a revised diagnosis for Amargatitanis macni as a valid taxon, and description of unpublished material clarifies the anatomy of this sauropod dinosaur. The inclusion of Amargatitanis macni in an updated phylogenetic analysis revealed the presence of a second species of the family Dicraeosauridae in the La Amarga Formation, suggesting that, at present, there is no record of titanosaur body fossils in Patagonia prior to Cenomanian times.

Turns out Sauropods Liked Pasta

First sauropod bones from Italy offer new insights on the radiation of Titanosauria between Africa and Europe

Authors:

Dal Sasso et al

Abstract:

Here we describe the first sauropod skeletal remains from the Italian peninsula that also represent the earliest record of titanosaurs in Southern Europe. Scattered bones, including an almost complete anterior caudal vertebra, were found in Cretaceous (Aptian–Albian) marine deposits, some 50 km East of Rome. The vertebra shows a bizarre and perhaps unique orientation of the zygapophyseal articular facets that renders their interpretation problematic. Phylogenetic retrofitting tests support the placement of the Italian titanosaur among basal lithostrotians. Palaeobiogeographic analysis based on the resulting phyletic relationships suggests an Afro-Eurasian route for the ancestors of the Italian titanosaur, a scenario compatible with the palaeogeographic evolution of the Italian microplates during the Cretaceous. Together with previously recorded titanosaurian-like ichnites from a Cenomanian locality in Latium, this new find suggests a quite long emersion for the Apenninic carbonate platform. We suggest that the Italian titanosaur was member of a population that crossed the western Tethys Sea through a “filtering bridge” composed of a chain of ephemeral islands and peninsulae, known as Periadriatic (Adria) carbonate platforms, that connected sporadically Africa and Europe since the Early Cretaceous.

A Rapetosaurus Titanosaur Sauropod Lived Fast, Died Young in Cretaceous Madagascar

Precocity in a tiny titanosaur from the Cretaceous of Madagascar

Authors:

Rogers et al

Abstract:

Sauropod dinosaurs exhibit the largest ontogenetic size range among terrestrial vertebrates, but a dearth of very young individuals has hindered understanding of the beginning of their growth trajectory. A new specimen of Rapetosaurus krausei sheds light on early life in the smallest stage of one of the largest dinosaurs. Bones record rapid growth rates and hatching lines, indicating that this individual weighed ~3.4 kilograms at hatching. Just several weeks later, when it likely succumbed to starvation in a drought-stressed ecosystem, it had reached a mass of ~40 kilograms and was ~35 centimeters tall at the hip. Unexpectedly, Rapetosaurus limb bones grew isometrically throughout their development. Cortical remodeling, limb isometry, and thin calcified hypertrophic metaphyseal cartilages indicate an active, precocial growth strategy.

A Highly Diverse Sauropod Fauna in the Earliest Cretaceous South Africa

High diversity in the sauropod dinosaur fauna of the Lower Cretaceous Kirkwood Formation of South Africa: Implications for the Jurassic–Cretaceous transition

Authors:

McPhee et al

Abstract:

The Kirkwood Formation of South Africa has long been recognized as having the potential to fill an important gap in the Mesozoic terrestrial fossil record. As one of the few fossil-bearing deposits from the lowermost Cretaceous, the Kirkwood Formation provides critical information on terrestrial ecosystems at the local, subcontinental (southern Gondwana), and global scale during this poorly sampled time interval. However, until recently, the dinosaurian fauna of the Kirkwood Formation, especially that pertaining to Sauropoda, has remained essentially unknown. Here we present comprehensive descriptions of several relatively well-preserved sauropod vertebrae collected from exposures throughout the formation. We identify at least four taxonomically distinct groups of sauropod, comprising representatives of Diplodocidae, Dicraeosauridae, Brachiosauridae, and a eusauropod that belongs to neither Diplodocoidea nor Titanosauriformes. This represents the first unequivocal evidence of these groups having survived into the earliest Cretaceous of Africa. The taxonomic composition of the Kirkwood Formation shows strong similarities to Upper Jurassic deposits, and raises questions regarding the taxonomic decline across the Jurassic/Cretaceous boundary that has been previously inferred for Sauropoda. Investigation of the sauropod fossil record of the first three geological stages of the Cretaceous suggests that reconstruction of sauropod macroevolutionary patterns is complicated by a combination of sampling bias, an uneven and poorly dated rock record, and spatiotemporal disparity in the global disappearance of certain sauropod groups. Nonetheless, the close ecological relationship consistently observed between Brachiosauridae and Diplodocidae, as well as their approximately synchronous decline, suggests some equivalence in response to the changing faunal dynamics of the Early Cretaceous.

Exploring the Paleobiodiversity of Sauropods in Cretaceous South America

Cretaceous sauropod diversity and taxonomic succession in South America

Authors:

de Jesus Faria et al

Abstract:

The South American sauropod dinosaurs fossil record is one of the world’s most relevant for their abundance (51 taxa) and biogeographical implications. Their historical biogeography was influenced by the continental fragmentation of Gondwana. The scenery of biogeographic and stratigraphic distributions can provide new insight into the causes of the evolution of the sauropods in South America. One of the most important events of the sauropods evolution is the progressive replacement of Diplodocimorpha by the Titanosauriformes during the early Late Cretaceous. The fluctuation of the sea levels is frequently related to the diversity of sauropods, but it is necessary to take into account the geological context in each continent. During the Maastrichthian, a global sea level drop has been described; in contrast, in South America there was a significant rise in sea level (named ‘Atlantic transgression’) which is confirmed by sedimentary sequences and the fossil record of marine vertebrates. This process occurred during the Maastrichtian, when the hadrosaurs arrived from North America. The titanosaurs were amazingly diverse during the Late Cretaceous, both in size and morphology, but they declined prior to their final extinction in the Cretaceous/Paleocene boundary (65.5Yrs).

How Species Rich Were the Titanosaur Sauropods of South America During the Campanian/Maastrichtian Cretaceous?

Species Richness and Evidence of Random Patterns in Assemblages of South American Titanosauria during the Late Cretaceous (Campanian–Maastrichtian)

Authors:

Silva Viera et al

Abstract:

The Titanosauria were much diversified during the Late Cretaceous, but paleobiological information concerning these sauropods continues to be scarce and no studies have been conducted utilizing modern methods of community analysis to infer possible structural patterns of extinct assemblages. The present study sought to estimate species richness and to investigate the existence of structures in assemblages of the South American Titanosauria during the Late Cretaceous. Estimates of species richness were made utilizing a nonparametric estimator and null models of species co-occurrences and overlapping body sizes were applied to determine the occurrence of structuring in this assemblages. The high estimate of species richness (n = 57) may have been influenced by ecological processes associated with extinction events of sauropod groups and with the structures of the habitats that provided abundant support to the maintenance of large numbers of species. The pseudocommunity analysis did not differ from that expected by chance, indicating the lack of structure in these assemblages. It is possible that these processes originated from phylogenetic inertia, associated with the occurrence of stabilized selection. Additionally, stochastic extinction events and historical factors may also have influenced the formation of the titanosaurian assemblages, in detriment to ecological factors during the Late Cretaceous. However, diagenetic and biostratinomic processes, influenced by the nature of the sedimentary paleoenvironment, could have rendered a random arrangement that would make assemblage structure undetectable.

Rukwatitan bisepultus: a new Endemic Titanosaurian Sauropod from Albian/Cenomanian Cretaceous Tanzania

Ohio University paleontologists have identified a new species of titanosaurian, a member of the large-bodied sauropods that thrived during the final period of the dinosaur age, in Tanzania. Although many fossils of titanosaurians have been discovered around the globe, especially in South America, few have been recovered from the continent of Africa.

The new species, named Rukwatitan bisepultus, was first spotted by scientists embedded in a cliff wall in the Rukwa Rift Basin of southwestern Tanzania. Using the help of professional excavators and coal miners, the team unearthed vertebrae, ribs, limbs and pelvic bones over the course of two field seasons.

CT scans of the fossils, combined with detailed comparisons with other sauropods, revealed unique features that suggested an animal that was different from previous finds—including those from elsewhere in Africa, according to a study the team published today in the Journal of Vertebrate Paleontology.

"Using both traditional and new computational approaches, we were able to place the new species within the family tree of sauropod dinosaurs and determine both its uniqueness as a species and to delineate others species with which it is most closely related," said lead author Eric Gorscak, a doctoral student in biological sciences at Ohio University.

Rukwatitan bisepultus lived approximately 100 million years ago during the middle of the Cretaceous Period. Titanosaurian sauropods, the group that includes Rukwatitan, were herbivorous dinosaurs known for their iconic large body sizes, long necks and wide stance. Although not among the largest of titanosaurians, Rukwatitan is estimated to have a forelimb reaching 2 meters and may have weighed as much as several elephants.

The dinosaur's bones exhibit similarities with another titanosaurian, Malawisaurus dixeyi, previously recovered in Malawi. But the two southern African dinosaurs are distinctly different from one another, and, most notably, from titanosaurians known from northern Africa, said co-author Patrick O'Connor, a professor of anatomy in the Ohio University Heritage College of Osteopathic Medicine.

The fossils of middle Cretaceous crocodile relatives from the Rukwa Rift Basin also exhibit distinctive features when compared to forms from elsewhere on the continent.

"There may have been certain environmental features, such as deserts, large waterways and/or mountain ranges, that would have limited the movement of animals and promoted the evolution of regionally distinct faunas," O'Connor said. "Only additional data on the faunas and paleo environments from around the continent will let us further test such hypotheses."

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Dreadnoughtus schrani: The new MASSIVE Titanosaur from Campanian/Maastrichtian Cretaceous Patagonia

A Gigantic, Exceptionally Complete Titanosaurian Sauropod Dinosaur from Southern Patagonia, Argentina

Authors:

Lacovara et al

Abstract:

Titanosaurian sauropod dinosaurs were the most diverse and abundant large-bodied herbivores in the southern continents during the final 30 million years of the Mesozoic Era. Several titanosaur species are regarded as the most massive land-living animals yet discovered; nevertheless, nearly all of these giant titanosaurs are known only from very incomplete fossils, hindering a detailed understanding of their anatomy. Here we describe a new and gigantic titanosaur, Dreadnoughtus schrani, from Upper Cretaceous sediments in southern Patagonia, Argentina. Represented by approximately 70% of the postcranial skeleton, plus craniodental remains, Dreadnoughtus is the most complete giant titanosaur yet discovered, and provides new insight into the morphology and evolutionary history of these colossal animals. Furthermore, despite its estimated mass of about 59.3 metric tons, the bone histology of the Dreadnoughtus type specimen reveals that this individual was still growing at the time of death.

A Titanosaur Sauropod From Maastrichtian Cretaceous Texas

New specimens of a titanosaur sauropod from the Maastrichtian of Big Bend National Park, Texas

Authors:

Fronimos et al

Abstract:

New specimens of a titanosaur sauropod from Maastrichtian strata in Big Bend National Park, Texas, include well-preserved dorsal vertebrae in association with pelvic elements. Anterior dorsal vertebrae are characterized by postspinal and centroprezygapophyseal laminae, with spinodiapophyseal laminae convergent on the anterior base of the neural spine. Posterior dorsal vertebrae are characterized by postzygodiapophyseal laminae and divided spinodiapophyseal laminae, with spinoprezygapophyseal laminae contributing to the prespinal lamina. The ilium and pubis differ from specimens previously collected, indicating a greater morphological disparity among titanosaurs in the Maastrichtian of West Texas than previously recognized. This disparity may be attributable to intraspecific variation or to the presence of multiple taxa. The new material is compatible with the only presently known North American titanosaur, Alamosaurus sanjuanensis, but is not formally referred due to lack of overlap with the hypodigm of that species. Comparison with other derived titanosaurs finds the closest affinities to Trigonosaurus pricei, Uberabatitan riberoi, and Baurutitan britoi of the Upper Cretaceous Brazilian Bauru Group, consistent with a South American immigration event at the end of the North American sauropod hiatus.

Reconstructing Titanosaur Sauropod Feeding Grounds From Maastrichtian Cretaceous Spain

Reconstructing the foraging environment of the latest titanosaurs (Fumanya dinosaur tracksite, Catalonia)

Authors:

Marmi et al

Abstract:

The analysis of depositional environments associated with sauropod dinosaurs has been revealed as a key element for assessing their palaeoecology. A detailed study of the sedimentology, plant taphofacies and titanosaur ichnology at the Fumanya localities (early Maastrichtian, Catalonia) reveals that two distinct palaeoenvironments existed within the coastal wetlands. These settings are correlated with the occurrence of two distinct track and plant remains distributions, which correspond to a) a marginal brackish lagoon environment where no vegetation grew and titanosaurs roamed, during a short time span, without apparently any preferential purpose, and b) a freshwater swamp area around charophyte lakes with evidence of vegetation growth (charophytes, palms, and probably ferns and cheirolepidiacean conifers) where titanosaurs congregated and fed actively during a long time span. These data indicate that titanosaurs trampled the muddy substrates of freshwater wetlands in order to forage according to the availability of plants.

Yongjinglong datangi: a new, Very Derived Titanosaur Sauropod From Albian/Cenomanian Cretaceous China

A team led by University of Pennsylvania paleontologists has characterized a new dinosaur based on fossil remains found in northwestern China. The species, a plant-eating sauropod named Yongjinglong datangi, roamed during the Early Cretaceous period, more than 100 million years ago. This sauropod belonged to a group known as Titanosauria, members of which were among the largest living creatures to ever walk the earth.

At roughly 50-60 feet long, the Yongjinglong individual discovered was a medium-sized Titanosaur. Anatomical evidence, however, points to it being a juvenile; adults may have been larger.

The find, reported in the journal PLOS ONE, helps clarify relationships among several sauropod species that have been found in the last few decades in China and elsewhere. Its features suggest that Yongjinglong is among the most derived, or evolutionarily advanced, of the Titanosaurs yet discovered from Asia.

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First Dinosaurs from Saudi Arabia Herald From Campanian-Maastrichtian Cretaceous

First Dinosaurs from Saudi Arabia

Authors:

Kear et al

Abstract:

Dinosaur remains from the Arabian subcontinent are exceedingly rare, and those that have been documented manifest indeterminate affinities. Consequently the discovery of a small, but diagnostic, accumulation of elements from Campanian-Maastrichtian (~75 Ma) deposits in northwestern Saudi Arabia is significant because it constitutes the first taxonomically identifiable dinosaur material described from the Arabian Peninsula. The fossils include a series of possible lithostrotian titanosaur caudal vertebrae, and some isolated theropod marginal teeth that share unique character states and metric parameters (analyzed using multivariate statistical methods) with derived abelisaurids – this is the first justifiable example of a non-avian carnivorous dinosaur clade from Arabia. The recognition of titanosaurians and abelisaurids from Saudi Arabia extends the palaeogeographical range of these groups along the entire northern Gondwanan margin during the latest Cretaceous. Moreover, given the extreme paucity of coeval occurrences elsewhere, the Saudi Arabian fossils provide a tantalizing glimpse into dinosaurian assemblage diversity within the region.