Reappraisal of sauropod dinosaur diversity in the Upper Cretaceous Winton Formation of Queensland, Australia, through 3D digitisation and description of new specimens.

Skeletal remains of sauropod dinosaurs have been known from Australia for over 100 years. Unfortunately, the classification of the majority of these specimens to species level has historically been impeded by their incompleteness. This has begun to change in the last 15 years, primarily through the discovery and description of several partial skeletons from the Cenomanian-lower Turonian (lower Upper Cretaceous) Winton Formation in central Queensland, with four species erected to date: Australotitan cooperensis, Diamantinasaurus matildae, Savannasaurus elliottorum, and Wintonotitan wattsi. The first three of these appear to form a clade (Diamantinasauria) of early diverging titanosaurs (or close relatives of titanosaurs), whereas Wintonotitan wattsi is typically recovered as a distantly related non-titanosaurian somphospondylan. Through the use of 3D scanning, we digitised numerous specimens of Winton Formation sauropods, facilitating enhanced comparison between type and referred specimens, and heretofore undescribed specimens. We present new anatomical information on the holotype specimen of Diamantinasaurus matildae, and describe new remains pertaining to twelve sauropod individuals. Firsthand observations and digital analysis enabled previously proposed autapomorphic features of all four named Winton Formation sauropod species to be identified in the newly described specimens, with some specimens exhibiting putative autapomorphies of more than one species, prompting a reassessment of their taxonomic validity. Supported by a specimen-level phylogenetic analysis, we suggest that Australotitan cooperensis is probably a junior synonym of Diamantinasaurus matildae, but conservatively regard it herein as an indeterminate diamantinasaurian, meaning that the Winton Formation sauropod fauna now comprises three (rather than four) valid diamantinasaurian species: Diamantinasaurus matildae, Savannasaurus elliottorum, and Wintonotitan wattsi, with the latter robustly supported as a member of the clade for the first time. We refer some of the newly described specimens to these three species and provide revised diagnoses, with some previously proposed autapomorphies now regarded as diamantinasaurian synapomorphies. Our newly presented anatomical data and critical reappraisal of the Winton Formation sauropods facilitates a more comprehensive understanding of the mid-Cretaceous sauropod palaeobiota of central Queensland.

Microbially mediated fossil concretions and their characterization by the latest methodologies: a review.

The study of well-preserved organic matter (OM) within mineral concretions has provided key insights into depositional and environmental conditions in deep time. Concretions of varied compositions, including carbonate, phosphate, and iron-based minerals, have been found to host exceptionally preserved fossils. Organic geochemical characterization of concretion-encapsulated OM promises valuable new information of fossil preservation, paleoenvironments, and even direct taxonomic information to further illuminate the evolutionary dynamics of our planet and its biota. Full exploitation of this largely untapped geochemical archive, however, requires a sophisticated understanding of the prevalence, formation controls and OM sequestration properties of mineral concretions. Past research has led to the proposal of different models of concretion formation and OM preservation. Nevertheless, the formation mechanisms and controls on OM preservation in concretions remain poorly understood. Here we provide a detailed review of the main types of concretions and formation pathways with a focus on the role of microbes and their metabolic activities. In addition, we provide a comprehensive account of organic geochemical, and complimentary inorganic geochemical, morphological, microbial and paleontological, analytical methods, including recent advancements, relevant to the characterization of concretions and sequestered OM. The application and outcome of several early organic geochemical studies of concretion-impregnated OM are included to demonstrate how this underexploited geo-biological record can provide new insights into the Earth's evolutionary record. This paper also attempts to shed light on the current status of this research and major challenges that lie ahead in the further application of geo-paleo-microbial and organic geochemical research of concretions and their host fossils. Recent efforts to bridge the knowledge and communication gaps in this multidisciplinary research area are also discussed, with particular emphasis on research with significance for interpreting the molecular record in extraordinarily preserved fossils.

A nearly complete skull of the sauropod dinosaur Diamantinasaurus matildae from the Upper Cretaceous Winton Formation of Australia and implications for the early evolution of titanosaurs.

Titanosaurian sauropod dinosaurs were diverse and abundant throughout the Cretaceous, with a global distribution. However, few titanosaurian taxa are represented by multiple skeletons, let alone skulls. Diamantinasaurus matildae, from the lower Upper Cretaceous Winton Formation of Queensland, Australia, was heretofore represented by three specimens, including one that preserves a braincase and several other cranial elements. Herein, we describe a fourth specimen of Diamantinasaurus matildae that preserves a more complete skull-including numerous cranial elements not previously known for this taxon-as well as a partial postcranial skeleton. The skull of Diamantinasaurus matildae shows many similarities to that of the coeval Sarmientosaurus musacchioi from Argentina (e.g. quadratojugal with posterior tongue-like process; braincase with more than one ossified exit for cranial nerve V; compressed-cone-chisel-like teeth), providing further support for the inclusion of both taxa within the clade Diamantinasauria. The replacement teeth within the premaxilla of the new specimen are morphologically congruent with teeth previously attributed to Diamantinasaurus matildae, and Diamantinasauria more broadly, corroborating those referrals. Plesiomorphic characters of the new specimen include a sacrum comprising five vertebrae (also newly demonstrated in the holotype of Diamantinasaurus matildae), rather than the six or more that typify other titanosaurs. However, we demonstrate that there have been a number of independent acquisitions of a six-vertebrae sacrum among Somphospondyli and/or that there have been numerous reversals to a five-vertebrae sacrum, suggesting that sacral count is relatively plastic. Other newly identified plesiomorphic features include: the overall skull shape, which is more similar to brachiosaurids than 'derived' titanosaurs; anterior caudal centra that are amphicoelous, rather than procoelous; and a pedal phalangeal formula estimated as 2-2-3-2-0. These features are consistent with either an early-branching position within Titanosauria, or a position just outside the titanosaurian radiation, for Diamantinasauria, as indicated by alternative character weighting approaches applied in our phylogenetic analyses, and help to shed light on the early assembly of titanosaurian anatomy that has until now been obscured by a poor fossil record.

Sauropod dinosaur teeth from the lower Upper Cretaceous Winton Formation of Queensland, Australia and the global record of early titanosauriforms.

The Upper Cretaceous Winton Formation of Queensland, Australia, has produced several partial sauropod skeletons, but cranial remains-including teeth-remain rare. Herein, we present the first description of sauropod teeth from this formation, based on specimens from three separate sites. An isolated tooth and a dentary fragment from the Diamantinasaurus matildae type locality are considered to be referable to that titanosaurian taxon. A single tooth from the D. matildae referred specimen site is similarly regarded as being part of that individual. Seventeen teeth from a new site that are morphologically uniform, and similar to the teeth from the two Diamantinasaurus sites, are assigned to Diamantinasauria. All sauropod teeth recovered from the Winton Formation to date are compressed-cone-chisel-shaped, have low slenderness index values (2.00-2.88), are lingually curved at their apices, mesiodistally convex on their lingual surfaces, and lack prominent carinae and denticles. They are markedly different from the chisel-like teeth of derived titanosaurs, more closely resembling the teeth of early branching members of the titanosauriform radiation. This provides further support for a 'basal' titanosaurian position for Diamantinasauria. Scanning electron microscope microwear analysis of the wear facets of several teeth reveals more scratches than pits, implying that diamantinasaurians were mid-height (1-10 m) feeders. With a view to assessing the spatio-temporal distribution of sauropod tooth morphotypes before and after deposition of the Winton Formation, we provide a comprehensive continent-by-continent review of the early titanosauriform global record (Early to early Late Cretaceous). This indicates that throughout the Early-early Late Cretaceous, sauropod faunas transitioned from being quite diverse at higher phylogenetic levels and encompassing a range of tooth morphologies at the start of the Berriasian, to faunas comprising solely titanosaurs with limited dental variability by the end-Turonian. Furthermore, this review highlights the different ways in which this transition unfolded on each continent, including the earliest records of titanosaurs with narrow-crowned teeth on each continent.

A diverse Late Cretaceous vertebrate tracksite from the Winton Formation of Queensland, Australia.

The Upper Cretaceous 'upper' Winton Formation of Queensland, Australia is world famous for hosting Dinosaur Stampede National Monument at Lark Quarry Conservation Park, a somewhat controversial tracksite that preserves thousands of tridactyl dinosaur tracks attributed to ornithopods and theropods. Herein, we describe the Snake Creek Tracksite, a new vertebrate ichnoassemblage from the 'upper' Winton Formation, originally situated on Karoola Station but now relocated to the Australian Age of Dinosaurs Museum of Natural History. This site preserves the first sauropod tracks reported from eastern Australia, a small number of theropod and ornithopod tracks, the first fossilised crocodyliform and ?turtle tracks reported from Australia, and possible lungfish and actinopterygian feeding traces. The sauropod trackways are wide-gauge, with manus tracks bearing an ungual impression on digit I, and anteriorly tapered pes tracks with straight or concave forward posterior margins. These tracks support the hypothesis that at least one sauropod taxon from the 'upper' Winton Formation retained a pollex claw (previously hypothesised for Diamantinasaurus matildae based on body fossils). Many of the crocodyliform trackways indicate underwater walking. The Snake Creek Tracksite reconciles the sauropod-, crocodyliform-, turtle-, and lungfish-dominated body fossil record of the 'upper' Winton Formation with its heretofore ornithopod- and theropod-dominated ichnofossil record.

New theropod remains and implications for megaraptorid diversity in the Winton Formation (lower Upper Cretaceous), Queensland, Australia.

The holotype specimen of the megaraptorid Australovenator wintonensis, from the Upper Cretaceous Winton Formation (Rolling Downs Group, Eromanga Basin) of central Queensland, is the most complete non-avian theropod found in Australia to date. In fact, the holotype of A. wintonensis and isolated megaraptorid teeth (possibly referable to Australovenator) constitute the only theropod body fossils reported from the Winton Formation. Herein, we describe a new fragmentary megaraptorid specimen from the Winton Formation, found near the type locality of A. wintonensis. The new specimen comprises parts of two vertebrae, two metatarsals, a pedal phalanx and multiple unidentifiable bone fragments. Although the new megaraptorid specimen is poorly preserved, it includes the only megaraptorid vertebrae known from Queensland. The presence of pleurocoels and highly pneumatic caudal centra with camerate and camellate internal structures permit the assignment of these remains to Megaraptora gen. et sp. indet. A morphological comparison revealed that the distal end of metatarsal II and the partial pedal phalanx II-1 of the new specimen are morphologically divergent from Australovenator. This might indicate the presence of a second megaraptorid taxon in the Winton Formation, or possibly intraspecific variation.

Ferrodraco lentoni gen. et sp. nov., a new ornithocheirid pterosaur from the Winton Formation (Cenomanian-lower Turonian) of Queensland, Australia.

The Australian pterosaur record is poor by world standards, comprising fewer than 20 fragmentary specimens. Herein, we describe the new genus and species Ferrodraco lentoni gen. et sp. nov., based on the most complete pterosaur specimen ever found in Australia, and the first reported from the Winton Formation (Cenomanian-lower Turonian). The presence of premaxillary and mandibular crests, and spike-shaped teeth with subcircular bases, enable Ferrodraco to be referred to Anhangueria. Ferrodraco can be distinguished from all other anhanguerian pterosaurs based on two dental characters: the first premaxillary and mandibular tooth pairs are small; and the fourth-seventh tooth pairs are smaller than the third and eighth ones. Ferrodraco was included in a phylogenetic analysis of Pterosauria and resolved as the sister taxon to Mythunga camara (upper Albian Toolebuc Formation, Australia), with that clade occupying the most derived position within Ornithocheiridae. Ornithocheirus simus (Albian Cambridge Greensand, England), Coloborhynchus clavirostris (Valanginian Hastings Sands, England), and Tropeognathus mesembrinus (upper Aptian-lower Albian Romualdo Formation, Brazil) were resolved as successive sister taxa, which suggests that ornithocheirids were cosmopolitan during the Albian-Cenomanian. Furthermore, the stratigraphic age of Ferrodraco lentoni (Cenomanian-lower Turonian) implies that anhanguerians might have survived later in Australia than elsewhere.

Comparative Three-Dimensional Moment Arm Analysis of the Sauropod Forelimb: Implications for the Transition to a Wide-Gauge Stance in Titanosaurs.

The evolution of extraordinarily large size among Sauropoda was associated with a number of biomechanical adaptations. Changes in muscle moment arms undoubtedly accompanied these adaptations, but since muscles rarely fossilize, our ability to understand them has been restricted. Here, we use three-dimensional (3D) musculoskeletal modeling to reconstruct and quantitatively assess leverage of forelimb muscles in the transition from the narrow-gauge stance of basal sauropods to a wide-gauge stance in titanosaurs. A comparative analysis is conducted on three neosauropods: the narrow-gauge diplodocid Apatosaurus louisae, the intermediate-gauge titanosariform Giraffatitan brancai, and the wide-gauge titanosaur Diamantinasaurus matildae. In this study, moment arm magnitudes and corresponding morphological evidence indicates multiple changes across the narrow-gauge to wide-gauge transition in sauropods. High shoulder adduction was found in Diamantinasaurus, suggesting functional changes for supporting a wider stance and a limb less aligned with ground reaction force. High leverage in shoulder extension of Diamantinasaurus and Giraffatitan is possibly related to the increased use of the forelimb in forward propulsion with an anterior shift in center of mass. In addition, the prominence of the olecranon process in Diamantinasaurus produced high moment arm leverage in elbow flexion and extension, suggesting titanosaurs might have maintained a more flexed forelimb posture and displayed an increased degree of maneuverability. Other results are more variable between taxa but still indicate smaller scale changes. A sensitivity analysis was also conducted to measure the reliability of our models and test specific uncertainties within the modeling process, as well as other uncertainties uncovered during analysis. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 302:794-817, 2019. © 2018 Wiley Periodicals, Inc.

Three-Dimensional Musculoskeletal Modeling of the Sauropodomorph Hind Limb: The Effect of Postural Change on Muscle Leverage.

The biomechanical constraints for life at massive size can be directly observed in the evolutionary history of sauropodomorph dinosaurs. Members of this lineage underwent a number of major postural transitions as they increased in size from relatively small bipedal dinosaurs to massive titanosaurs that include the largest terrestrial animals of all time. To better understand the impact of gigantic size on the biomechanics of sauropods, we used three-dimensional musculoskeletal modeling to investigate how hind limb musculature was affected, first by the development of a quadrupedal stance from a bipedal one, and later in the transition from a narrow-gauge to a wide-gauge stance. Muscle moment arms were measured in four sauropodomorph taxa: the bipedal basal sauropodomorph Plateosaurus engelhardti, the narrow-gauge diplodocid Diplodocus carnegii, the titanosauriform Giraffatitan brancai, and the wide-gauge titanosaur Diamantinasaurus matildae. In Plateosaurus, low moment arm leverage in the hip extensors and knee flexors and extensors was observed suggesting high-velocity movement for fast locomotion. A reduction in hip extensor leverage in Diamantinasaurus was found which suggests a reduced role for the hind limb in forward propulsion in titanosaurs. An increase in overall hip adductor leverage and leverage of adductors 1 and 2 in Diamantinasaurus, compared with other taxa studied, might relate to the development of a wide-gauge stance. High knee flexor-extensor leverage in Giraffatitan but not Diamantinasaurus partially refutes the idea that broader femoral condyles in titanosauriforms increased knee torque production capabilities. Sauropodomorph postural changes clearly had an impact on the function and leverage of hind limb muscles. Anat Rec, 301:2145-2163, 2018. © 2018 Wiley Periodicals, Inc.

New Australian sauropods shed light on Cretaceous dinosaur palaeobiogeography.

Australian dinosaurs have played a rare but controversial role in the debate surrounding the effect of Gondwanan break-up on Cretaceous dinosaur distribution. Major spatiotemporal gaps in the Gondwanan Cretaceous fossil record, coupled with taxon incompleteness, have hindered research on this effect, especially in Australia. Here we report on two new sauropod specimens from the early Late Cretaceous of Queensland, Australia, that have important implications for Cretaceous dinosaur palaeobiogeography. Savannasaurus elliottorum gen. et sp. nov. comprises one of the most complete Cretaceous sauropod skeletons ever found in Australia, whereas a new specimen of Diamantinasaurus matildae includes the first ever cranial remains of an Australian sauropod. The results of a new phylogenetic analysis, in which both Savannasaurus and Diamantinasaurus are recovered within Titanosauria, were used as the basis for a quantitative palaeobiogeographical analysis of macronarian sauropods. Titanosaurs achieved a worldwide distribution by at least 125 million years ago, suggesting that mid-Cretaceous Australian sauropods represent remnants of clades which were widespread during the Early Cretaceous. These lineages would have entered Australasia via dispersal from South America, presumably across Antarctica. High latitude sauropod dispersal might have been facilitated by Albian-Turonian warming that lifted a palaeoclimatic dispersal barrier between Antarctica and South America.

The dentary of Australovenator wintonensis (Theropoda, Megaraptoridae); implications for megaraptorid dentition.

Megaraptorid theropods were an enigmatic group of medium-sized predatory dinosaurs, infamous for the hypertrophied claw on the first manual digit. Megaraptorid dentition is largely restricted to isolated teeth found in association with skeletal parts; however, the in situ maxillary dentition of Megaraptor was recently described. A newly discovered right dentary pertaining to the Australovenator holotype preserves in situ dentition, permitting unambiguous characterisation of the dentary tooth morphology. The new jaw is virtually complete, with an overall elongate, shallow profile, and fifteen visible in situ teeth at varying stages of eruption. In situ teeth confirm Australovenator exhibited modest pseudoheterodonty, recurved lateral teeth with a serrate distal carina and reduced mesial carina, similar to other megaraptorids. Australovenator also combines of figure-of-eight basal cross-section with a lanceolate shape due to the presence of labial and lingual depressions and the lingual twist of the distal carina. Computed tomography and three-dimensional imagery provided superior characterisation of the dentary morphology and enabled an accurate reconstruction to a pre-fossilised state. The newly established dental morphology also afforded re-evaluation of isolated theropod teeth discovered at the Australovenator holotype locality and from several additional Winton Formation localities. The isolated Winton teeth are qualitatively and quantitatively similar to the in situ dentary teeth of Australovenator, but are also morphometrically similar to Abelisauridae, Allosauridae, Coelophysoidea, Megalosauridae and basal Tyrannosauroidea. Qualitative characters, however, clearly distinguish the teeth of Australovenator and the isolated Winton teeth from all other theropods. Evidence from teeth suggests megaraptorids were the dominant predators in the Winton Formation, which contrasts with other penecontemporaneous Gondwanan ecosystems.

Photographic Atlas and three-dimensional reconstruction of the holotype skull of Euhelopus zdanskyi with description of additional cranial elements.

BACKGROUND: Euhelopus zdanskyi is one of relatively few sauropod taxa known from an almost complete skull and mandible. Recent phylogenetic analyses suggest that Euhelopus is a somphospondylan titanosauriform, and that it is a member of the clade (Euhelopodidae) which is the sister taxon to the hugely successful, dominantly Cretaceous sauropod group Titanosauria. METHODOLOGY/PRINCIPAL FINDINGS: The skull elements of Euhelopus were CT scanned at Uppsala Akademiska Sjukhuset. Three-dimensional models of the elements were constructed from the DICOM data using Mimics 14.0, InVesalius 3.0, and GeoMagic Studio 2012, the skull was rearticulated in Rhinoceros 4.0, and the final version was rendered in GeoMagic Studio 2012. CONCLUSIONS/SIGNIFICANCE: The fact that relatively complete sauropod skulls are so rare in the fossil record, particularly among titanosauriforms, means that the skulls that are known should be as thoroughly described and well-illustrated as possible. This contribution supplements previous descriptions of the cranial elements of Euhelopus, one of the few euhelopodid taxa for which cranial material is known, by presenting a comprehensive photographic atlas of the skull elements to facilitate a better understanding of their morphology. We describe several elements which have been overlooked in past studies of Euhelopus, and also provide as accurate a reconstruction of the skull as possible (in the absence of the braincase), the most significant components of which are the articulations of the palate and the mandible.

New Australovenator hind limb elements pertaining to the holotype reveal the most complete Neovenatorid leg.

We report new skeletal elements pertaining to the same individual which represents the holotype of Australovenator wintonensis, from the 'Matilda Site' in the Winton Formation (Upper Cretaceous) of western Queensland. The discovery of these new elements means that the hind limb of Australovenator is now the most completely understood hind limb among Neovenatoridae. The new hind limb elements include: the left fibula; left metatarsal IV; left pedal phalanges I-2, II-1, III-4, IV-2, IV-3; and right pedal phalanges, II-2 and III-1. The detailed descriptions are supported with three dimensional figures. These coupled with the completeness of the hind limb will increase the utility of Australovenator in comparisons with less complete neovenatorid genera. These specimens and the previously described hind limb elements of Australovenator are compared with other theropods classified as neovenatorids (including Neovenator, Chilantaisaurus, Fukuiraptor, Orkoraptor and Megaraptor). Hind limb length proportion comparisons indicate that the smaller neovenatorids Australovenator and Fukuiraptor possess more elongate and gracile hind limb elements than the larger Neovenator and Chilantaisaurus. Greater stride lengths to body size exist in both Fukuiraptor and Australovenator with the femur discovered to be proportionally shorter the rest of the hind limb length. Additionally Australovenator is identified as possessing the most elongate metatarsus. The metatarsus morphology varies with body size. The larger neoventorids possess a metatarsus with greater width but shorter length compared to smaller forms.