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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., Competing Interests: The authors declare that they have no competing interests., (© 2024 Beeston et al.)

Dinosaurs dominated Mesozoic terrestrial ecosystems globally. However, whereas a pole-to-pole geographic distribution characterized ornithischians and theropods, sauropods were restricted to lower latitudes. Here, we evaluate the role of climate in shaping these biogeographic patterns through the Jurassic-Cretaceous (201-66 mya), combining dinosaur fossil occurrences, past climate data from Earth System models, and habitat suitability modeling. Results show that, uniquely among dinosaurs, sauropods occupied climatic niches characterized by high temperatures and strongly bounded by minimum cold temperatures. This constrained the distribution and dispersal pathways of sauropods to tropical areas, excluding them from latitudinal extremes, especially in the Northern Hemisphere. The greater availability of suitable habitat in the southern continents, particularly in the Late Cretaceous, might be key to explaining the high diversity of sauropods there, relative to northern landmasses. Given that ornithischians and theropods show a flattened or bimodal latitudinal biodiversity gradient, with peaks at higher latitudes, the closer correspondence of sauropods to a subtropical concentration could hint at fundamental thermophysiological differences to the other two clades., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The Cretaceous/Paleogene mass extinction, 66 Ma, included the demise of non-avian dinosaurs. Intense debate has focused on the relative roles of Deccan volcanism and the Chicxulub asteroid impact as kill mechanisms for this event. Here, we combine fossil-occurrence data with paleoclimate and habitat suitability models to evaluate dinosaur habitability in the wake of various asteroid impact and Deccan volcanism scenarios. Asteroid impact models generate a prolonged cold winter that suppresses potential global dinosaur habitats. Conversely, long-term forcing from Deccan volcanism (carbon dioxide [CO 2 ]-induced warming) leads to increased habitat suitability. Short-term (aerosol cooling) volcanism still allows equatorial habitability. These results support the asteroid impact as the main driver of the non-avian dinosaur extinction. By contrast, induced warming from volcanism mitigated the most extreme effects of asteroid impact, potentially reducing the extinction severity., Competing Interests: The authors declare no competing interest., (Copyright © 2020 the Author(s). Published by PNAS.)

In the lead-up to the Cretaceous/Paleogene mass extinction, dinosaur diversity is argued to have been either in long-term decline, or thriving until their sudden demise. The latest Cretaceous (Campanian-Maastrichtian [83-66 Ma]) of North America provides the best record to address this debate, but even here diversity reconstructions are biased by uneven sampling. Here we combine fossil occurrences with climatic and environmental modelling to quantify latest Cretaceous North American dinosaur habitat. Ecological niche modelling shows a Campanian-to-Maastrichtian habitability decrease in areas with present-day rock-outcrop. However, a continent-wide projection demonstrates habitat stability, or even a Campanian-to-Maastrichtian increase, that is not preserved. This reduction of the spatial sampling window resulted from formation of the proto-Rocky Mountains and sea-level regression. We suggest that Maastrichtian North American dinosaur diversity is therefore likely to be underestimated, with the apparent decline a product of sampling bias, and not due to a climatically-driven decrease in habitability as previously hypothesised.

The fragmentation of the supercontinent Pangaea has been suggested to have had a profound impact on Mesozoic terrestrial vertebrate distributions. One current paradigm is that geographic isolation produced an endemic biota in East Asia during the Jurassic, while simultaneously preventing diplodocoid sauropod dinosaurs and several other tetrapod groups from reaching this region. Here we report the discovery of the earliest diplodocoid, and the first from East Asia, to our knowledge, based on fossil material comprising multiple individuals and most parts of the skeleton of an early Middle Jurassic dicraeosaurid. The new discovery challenges conventional biogeographical ideas, and suggests that dispersal into East Asia occurred much earlier than expected. Moreover, the age of this new taxon indicates that many advanced sauropod lineages originated at least 15 million years earlier than previously realised, achieving a global distribution while Pangaea was still a coherent landmass.

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 sauropod dinosaur "Pelorosaurus" becklesii was named in 1852 on the basis of an associated left humerus, ulna, radius and skin impression from the Early Cretaceous (Berriasian-Valanginian) Hastings Beds Group, near Hastings, East Sussex, southeast England, United Kingdom. The taxonomy and nomenclature of this specimen have a complex history, but most recent workers have agreed that "P." becklesii represents a distinct somphospondylan (or at least a titanosauriform) and is potentially the earliest titanosaur body fossil from Europe or even globally. The Hastings specimen is distinct from the approximately contemporaneous Pelorosaurus conybeari from Tilgate Forest, West Sussex. "P." becklesii can be diagnosed on the basis of five autapomorphies, such as: a prominent anteriorly directed process projecting from the anteromedial corner of the distal humerus; the proximal end of the radius is widest anteroposteriorly along its lateral margin; and the unique combination of a robust ulna and slender radius. The new generic name Haestasaurus is therefore erected for "P." becklesii. Three revised and six new fore limb characters (e.g. the presence/absence of condyle-like projections on the posterodistal margin of the radius) are discussed and added to three cladistic data sets for Sauropoda. Phylogenetic analysis confirms that Haestasaurus becklesii is a macronarian, but different data sets place this species either as a non-titanosauriform macronarian, or within a derived clade of titanosaurs that includes Malawisaurus and Saltasauridae. This uncertainty is probably caused by several factors, including the incompleteness of the Haestasaurus holotype and rampant homoplasy in fore limb characters. Haestasaurus most probably represents a basal macronarian that independently acquired the robust ulna, enlarged olecranon, and other states that have previously been regarded as synapomorphies of clades within Titanosauria. There is growing evidence that basal macronarian taxa survived into the Early Cretaceous of Europe and North America.

Non-avian dinosaurs went extinct 66 million years ago, geologically coincident with the impact of a large bolide (comet or asteroid) during an interval of massive volcanic eruptions and changes in temperature and sea level. There has long been fervent debate about how these events affected dinosaurs. We review a wealth of new data accumulated over the past two decades, provide updated and novel analyses of long-term dinosaur diversity trends during the latest Cretaceous, and discuss an emerging consensus on the extinction's tempo and causes. Little support exists for a global, long-term decline across non-avian dinosaur diversity prior to their extinction at the end of the Cretaceous. However, restructuring of latest Cretaceous dinosaur faunas in North America led to reduced diversity of large-bodied herbivores, perhaps making communities more susceptible to cascading extinctions. The abruptness of the dinosaur extinction suggests a key role for the bolide impact, although the coarseness of the fossil record makes testing the effects of Deccan volcanism difficult., (© 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.)

Large-scale adaptive radiations might explain the runaway success of a minority of extant vertebrate clades. This hypothesis predicts, among other things, rapid rates of morphological evolution during the early history of major groups, as lineages invade disparate ecological niches. However, few studies of adaptive radiation have included deep time data, so the links between extant diversity and major extinct radiations are unclear. The intensively studied Mesozoic dinosaur record provides a model system for such investigation, representing an ecologically diverse group that dominated terrestrial ecosystems for 170 million years. Furthermore, with 10,000 species, extant dinosaurs (birds) are the most speciose living tetrapod clade. We assembled composite trees of 614-622 Mesozoic dinosaurs/birds, and a comprehensive body mass dataset using the scaling relationship of limb bone robustness. Maximum-likelihood modelling and the node height test reveal rapid evolutionary rates and a predominance of rapid shifts among size classes in early (Triassic) dinosaurs. This indicates an early burst niche-filling pattern and contrasts with previous studies that favoured gradualistic rates. Subsequently, rates declined in most lineages, which rarely exploited new ecological niches. However, feathered maniraptoran dinosaurs (including Mesozoic birds) sustained rapid evolution from at least the Middle Jurassic, suggesting that these taxa evaded the effects of niche saturation. This indicates that a long evolutionary history of continuing ecological innovation paved the way for a second great radiation of dinosaurs, in birds. We therefore demonstrate links between the predominantly extinct deep time adaptive radiation of non-avian dinosaurs and the phenomenal diversification of birds, via continuing rapid rates of evolution along the phylogenetic stem lineage. This raises the possibility that the uneven distribution of biodiversity results not just from large-scale extrapolation of the process of adaptive radiation in a few extant clades, but also from the maintenance of evolvability on vast time scales across the history of life, in key lineages., Competing Interests: The authors have declared that no competing interests exist.

Background: The Late Cretaceous titanosauriform sauropod Huabeisaurus allocotus Pang and Cheng is known from teeth and much of the postcranial skeleton. Its completeness makes it an important taxon for integrating and interpreting anatomical observations from more fragmentary Cretaceous East Asian sauropods and for understanding titanosauriform evolution in general., Methodology/principal Findings: We present a detailed redescription of Huabeisaurus allocotus and a suite of anatomical comparisons with other titanosauriforms that demonstrate its validity via autapomorphies (e.g., division of some presacral vertebral laminae, reduced development of caudal ribs, the development of fossae relative to one another in caudal vertebral neural arches, high tibia-to-femur ratio). Huabeisaurus shares many features with other Cretaceous East Asian sauropods (e.g., pendant cervical ribs, anterior-middle caudal vertebrae with a nearly flat anterior centrum face and a concave posterior centrum face) that are absent in sauropods from other landmasses and strata, suggesting a close relationship among many of these forms within the clade Somphospondyli., Conclusions/significance: Restudy of Huabeisaurus provides further evidence for the existence of a clade of somphospondylans--Euhelopodidae--mainly found in the Cretaceous of East Asia. Euhelopodidae represents a fourth example of the evolution of narrow crowns within Sauropoda, along with diplodocoids, brachiosaurids, and advanced titanosaurs (lithostrotians). Despite being known from fewer species than Diplodocoidea, Brachiosauridae, or Lithostrotia, euhelopodids possessed a broader range of tooth shapes than any of these clades, suggesting that euhelopodids exemplified a comparably broad range of feeding strategies and perhaps diets.

Statistical models are helping palaeontologists to elucidate the history of biodiversity. Sampling standardization has been extensively applied to remedy the effects of uneven sampling in large datasets of fossil invertebrates. However, many vertebrate datasets are smaller, and the issue of uneven sampling has commonly been ignored, or approached using pairwise comparisons with a numerical proxy for sampling effort. Although most authors find a strong correlation between palaeodiversity and sampling proxies, weak correlation is recorded in some datasets. This has led several authors to conclude that uneven sampling does not influence our view of vertebrate macroevolution. We demonstrate that multi-variate regression models incorporating a model of underlying biological diversification, as well as a sampling proxy, fit observed sauropodomorph dinosaur palaeodiversity best. This bivariate model is a better fit than separate univariate models, and illustrates that observed palaeodiversity is a composite pattern, representing a biological signal overprinted by variation in sampling effort. Multi-variate models and other approaches that consider sampling as an essential component of palaeodiversity are central to gaining a more complete understanding of deep time vertebrate diversification.

The fossil record is our primary window onto the diversification of ancient life, but there are widespread concerns that sampling biases may distort observed palaeodiversity counts. Such concerns have been reinforced by numerous studies that found correlations between measures of sampling intensity and observed diversity. However, correlation does not necessarily mean that sampling controls observed diversity: an alternative view is that both sampling and diversity may be driven by some common factor (e.g. variation in continental flooding driven by sea level). The latter is known as the 'common cause' hypothesis. Here, we present quantitative analyses of the relationships between dinosaur diversity, sampling of the dinosaur fossil record, and changes in continental flooding and sea level, providing new insights into terrestrial common cause. Although raw data show significant correlations between continental flooding/sea level and both observed diversity and sampling, these correlations do not survive detrending or removal of short-term autocorrelation. By contrast, the strong correlation between diversity and sampling is robust to various data transformations. Correlations between continental flooding/sea level and taxic diversity/sampling result from a shared upward trend in all data series, and short-term changes in continental flooding/sea level and diversity/sampling do not correlate. The hypothesis that global dinosaur diversity is tied to sea-level fluctuations is poorly supported, and terrestrial common cause is unsubstantiated as currently conceived. Instead, we consider variation in sampling to be the preferred null hypothesis for short-term diversity variation in the Mesozoic terrestrial realm.

The accurate reconstruction of palaeobiodiversity patterns is central to a detailed understanding of the macroevolutionary history of a group of organisms. However, there is increasing evidence that diversity patterns observed directly from the fossil record are strongly influenced by fluctuations in the quality of our sampling of the rock record; thus, any patterns we see may reflect sampling biases, rather than genuine biological signals. Previous dinosaur diversity studies have suggested that fluctuations in sauropodomorph palaeobiodiversity reflect genuine biological signals, in comparison to theropods and ornithischians whose diversity seems to be largely controlled by the rock record. Most previous diversity analyses that have attempted to take into account the effects of sampling biases have used only a single method or proxy: here we use a number of techniques in order to elucidate diversity. A global database of all known sauropodomorph body fossil occurrences (2024) was constructed. A taxic diversity curve for all valid sauropodomorph genera was extracted from this database and compared statistically with several sampling proxies (rock outcrop area and dinosaur-bearing formations and collections), each of which captures a different aspect of fossil record sampling. Phylogenetic diversity estimates, residuals and sample-based rarefaction (including the first attempt to capture 'cryptic' diversity in dinosaurs) were implemented to investigate further the effects of sampling. After 'removal' of biases, sauropodomorph diversity appears to be genuinely high in the Norian, Pliensbachian-Toarcian, Bathonian-Callovian and Kimmeridgian-Tithonian (with a small peak in the Aptian), whereas low diversity levels are recorded for the Oxfordian and Berriasian-Barremian, with the Jurassic/Cretaceous boundary seemingly representing a real diversity trough. Observed diversity in the remaining Triassic-Jurassic stages appears to be largely driven by sampling effort. Late Cretaceous diversity is difficult to elucidate and it is possible that this interval remains relatively under-sampled. Despite its distortion by sampling biases, much of sauropodomorph palaeobiodiversity can be interpreted as a reflection of genuine biological signals, and fluctuations in sea level may account for some of these diversity patterns., (© 2010 The Authors. Biological Reviews © 2010 Cambridge Philosophical Society.)

Hudiesaurus sinojapanorum is a Late Jurassic sauropod from northwestern China that was erected on the basis of a cervicodorsal vertebra, four teeth, and a nearly complete forelimb. However, re-evaluation of this material, and comparisons with other taxa, indicate that there are few grounds for regarding these specimens as congeneric. Consequently, although we retain the vertebra as the holotype specimen of Hudiesaurus, the forelimb is assigned to a new taxon—Rhomaleopakhus turpanensis, gen. et sp. nov. The teeth previously referred to Hudiesaurus are poorly preserved but resemble those of several other 'core Mamenchisaurus-like taxa' (CMTs) from East Asia, such as Mamenchisaurus sinocanadorum. Phylogenetic analyses confirm that Hudiesaurus is a CMT and the sister taxon of Xinjiangtitan. Despite some uniquely shared features, their large size, and close geographic provenance, Hudiesaurus and Xinjiangtitan are retained as distinct genera based on their stratigraphic separation and numerous anatomical differences. Rhomaleopakhus is also shown to be a CMT in all analyses, being most closely related to Chuanjiesaurus and Analong. We link the convergent evolution of robust antebrachia and an enlarged olecranon in CMTs, titanosaurs, and some ornithischians (e.g., ceratopsids) to a more flexed orientation of the forearm, an enhanced role for the forelimb in locomotion, and an anterior shift in the whole-body center of mass. CMTs and titanosaurs potentially converged on a feeding strategy in which the ability to increase browse height via bipedal rearing was sacrificed in return for more efficient locomotion that improved travel between patchily distributed food sources. [ABSTRACT FROM AUTHOR]

The titanosaurian sauropod dinosaur Diamantinasaurus matildae is represented by two individuals from the Cenomanian–lower Turonian 'upper' Winton Formation of central Queensland, north-eastern Australia. The type specimen has been described in detail, whereas the referred specimen, which includes several elements not present in the type series (partial skull, atlas, axis and postaxial cervical vertebrae), has only been described briefly. Herein, we provide a comprehensive description of this referred specimen, including a thorough assessment of the external and internal anatomy of the braincase, and identify several new autapomorphies of D. matildae. Via an expanded data matrix consisting of 125 taxa scored for 552 characters, we recover a close, well-supported relationship between Diamantinasaurus and its contemporary, Savannasaurus elliottorum. Unlike previous iterations of this data matrix, under a parsimony framework we consistently recover Diamantinasaurus and Savannasaurus as early-diverging members of Titanosauria using both equal weighting and extended implied weighting, with the overall topology largely consistent between analyses. We erect a new clade, named Diamantinasauria herein, that also includes the contemporaneous Sarmientosaurus musacchioi from southern Argentina, which shares several cranial features with the referred Diamantinasaurus specimen. Thus, Diamantinasauria is represented in the mid-Cretaceous of both South America and Australia, supporting the hypothesis that some titanosaurians, in addition to megaraptoran theropods and possibly some ornithopods, were able to disperse between these two continents via Antarctica. Conversely, there is no evidence for rebbachisaurids in Australia, which might indicate that they were unable to expand into high latitudes before their extinction in the Cenomanian–Turonian. Likewise, there is no evidence for titanosaurs with procoelous caudal vertebrae in the mid-Cretaceous Australian record, despite scarce but compelling evidence for their presence in both Antarctica and New Zealand during the Campanian–Maastrichtian. These later titanosaurs presumably dispersed into these landmasses from South America before the Campanian (~85 Mya), when seafloor spreading between Zealandia and Australia commenced. Although Australian mid-Cretaceous dinosaur faunas appear to be cosmopolitan at higher taxonomic levels, closer affinities with South America at finer scales are becoming better supported for sauropods, theropods and ornithopods. [ABSTRACT FROM AUTHOR]

Spatiotemporal changes in fossil specimen completeness can bias our understanding of a group's evolutionary history. The quality of the sauropodomorph fossil record was assessed a decade ago, but the number of valid species has since increased by 60%, and 17% of the taxa from that study have since undergone taxonomic revision. Here, we assess how 10 years of additional research has changed our outlook on the group's fossil record. We quantified the completeness of all 307 sauropodomorph species currently considered valid using the skeletal completeness metric, which calculates the proportion of a complete skeleton preserved for each taxon. Taxonomic and stratigraphic age revisions, rather than new species, are the drivers of the most significant differences between the current results and those of the previous assessment. No statistical differences appeared when we use our new dataset to generate temporal completeness curves based solely on taxa known in 2009 or 1999. We now observe a severe drop in mean completeness values across the Jurassic–Cretaceous boundary that never recovers to pre‐Cretaceous levels. Explaining this pattern is difficult, as we find no convincing evidence that it is related to environmental preferences or body size changes. Instead, it might result from: (1) reduction of terrestrial fossil preservation space due to sea level rise; (2) ecological specificities and relatively high diagnosability of Cretaceous species; and/or (3) increased sampling of newly explored sites with many previously unknown taxa. Revisiting patterns in this manner allows us to test the longevity of conclusions made in previous quantitative studies. [ABSTRACT FROM AUTHOR]

The titanosaurian sauropod dinosaur Savannasaurus elliottorum is represented by a partial postcranial skeleton from the lower Upper Cretaceous (Cenomanian–lowermost Turonian) Winton Formation of Queensland, northeast Australia. Here, we present a detailed description of this specimen, as well as an emended diagnosis for this titanosaur. Savannasaurus elliottorum displays numerous character states that are generally regarded as plesiomorphic for Titanosauria, as well as several traits that are often regarded as apomorphic of that clade or a less inclusive subset thereof. Several features of Savannasaurus support a close relationship with the coeval Diamantinasaurus matildae, and this clade appears to occupy an early-branching position within Titanosauria. Relative to body size, the thoracic and abdominal breadth of Savannasaurus is greater than that seen in giant titanosaurs such as the contemporaneous South American lognkosaurians; however, this relative breadth is not quite as extreme as that of the small-bodied latest Cretaceous saltasaurines, or Opisthocoelicaudia skarzynskii. The possible advantages engendered by the barrel-shaped thorax, robust limbs, wide-gauge gait, and lack of hyposphene-hypantrum articulations are explored, and it is hypothesized that these traits were positively selected by the wet, temperate floodplain environment in which Savannasaurus lived. Greater stability and flexibility might have reduced the risk of bogging, and/or facilitated more expedient self-extraction from muddy waterholes. Similar environmental pressures acting upon other titanosaurian taxa or clades elsewhere might have led to the repeated independent development, or accentuation, of the bauplan regarded as 'typical' for the clade Titanosauria. This would explain the many observed convergences between Savannasaurus and Diamantinasaurus, and Saltasauridae. [ABSTRACT FROM AUTHOR]

There is no consensus about how terrestrial biodiversity was assembled through deep time, and in particular whether it has risen exponentially over the Phanerozoic. Using a database of 60 859 fossil occurrences, we show that the spatial extent of the worldwide terrestrial tetrapod fossil record itself expands exponentially through the Phanerozoic. Changes in spatial sampling explain up to 67% of the change in known fossil species counts, and these changes are decoupled from variation in habitable land area that existed through time. Spatial sampling therefore represents a real and profound sampling bias that cannot be explained as redundancy. To address this bias, we estimate terrestrial tetrapod diversity for palaeogeographical regions of approximately equal size. We find that regional-scale diversity was constrained over timespans of tens to hundreds of millions of years, and similar patterns are recovered for major subgroups, such as dinosaurs, mammals and squamates. Although the Cretaceous/Palaeogene mass extinction catalysed an abrupt two- to three-fold increase in regional diversity 66 million years ago, no further increases occurred, and recent levels of regional diversity do not exceed those of the Palaeogene. These results parallel those recovered in analyses of local community-level richness. Taken together, our findings strongly contradict past studies that suggested unbounded diversity increases at local and regional scales over the last 100 million years. [ABSTRACT FROM AUTHOR]

The Late Jurassic Tendaguru Formation of Tanzania, southeastern Africa, records a rich sauropod fauna, including the diplodocoids Dicraeosaurus and Tornieria, and the brachiosaurid titanosauriform Giraffatitan. However, the taxonomic affinities of other sympatric sauropod taxa are poorly understood. Here, we critically reassess and redescribe these problematic taxa, and present the largest phylogenetic analysis for sauropods (117 taxa scored for 542 characters) to explore their placement in Eusauropoda. Janenschia robusta has played a prominent role in discussions of titanosaur origins, with various authors referring at least some remains to Titanosauria, a clade otherwise known only from the Cretaceous. Redescription of the holotype of Janenschia, and all referable remains, supports its validity and placement as a non-neosauropod eusauropod. It forms a clade with Haestasaurus from the earliest Cretaceous of the UK, and the Middle/Late Jurassic Chinese sauropod Bellusaurus. Phylogenetic analysis and CT scans of the internal pneumatic tissue structure of Australodocus bohetii tentatively support a non-titanosaurian somphospondylan identification, making it the only known pre-Cretaceous representative of that clade. New information on the internal pneumatic tissue structure of the dorsal vertebrae of the enigmatic Tendaguria tanzaniensis, coupled with a full redescription, results in its novel placement as a turiasaur. Tendaguria is the sister taxon of Moabosaurus, from the Early Cretaceous of North America, and is the first turiasaur recognized from Gondwana. A previously referred caudal sequence cannot be assigned to Janenschia and displays several features that indicate a close relationship with Middle–Late Jurassic East Asian mamenchisaurids. It can be diagnosed by six autapomorphies, so we erect the new taxon Wamweracaudia keranjei gen. et sp. nov. The presence of a mamenchisaurid in the Late Jurassic of southern Gondwana indicates an earlier and more widespread diversification of this clade than previously realized, prior to the geographic isolation of East Asia. Our revised phylogenetic dataset sheds light on the evolutionary history of Eusauropoda, including supporting a basal diplodocoid placement for Haplocanthosaurus, and elucidating the interrelationships of rebbachisaurids. The Tendaguru Formation shares representatives of nearly all sauropod lineages with Middle Jurassic–earliest Cretaceous global faunas, but displays a greater range of diversity than any of those faunas considered individually. Biogeographic analysis indicates that the Tendaguru sauropod fauna was assembled as a result of three main phenomena during the late Early and/or Middle Jurassic: (1) invasions from Euramerica (brachiosaurids, turiasaurs); (2) endemism in west Gondwana (dicraeosaurids, diplodocids); and (3) regional extinctions that restricted the ranges of once widespread groups (mamenchisaurids, the Janenschia lineage). Multiple dispersals across the Central Gondwanan Desert are required to explain the distributions of Jurassic sauropods, suggesting that this geographic feature was at most a filter barrier that became easier to cross during the late Middle Jurassic. [ABSTRACT FROM AUTHOR]

The Jurassic/Cretaceous (J/K) boundary, 145 million years ago, has long been recognised as an extinction event or faunal turnover for sauropod dinosaurs, with many 'basal' lineages disappearing. However, recently, a number of 'extinct' groups have been recognised in the Early Cretaceous, including diplodocids in Gondwana, and non-titanosauriform macronarians in Laurasia. Turiasauria, a clade of non-neosauropod eusauropods, was originally thought to have been restricted to the Late Jurassic of western Europe. However, its distribution has recently been extended to the Late Jurassic of Tanzania (Tendaguria tanzaniensis), as well as to the Early Cretaceous of the USA (Mierasaurus bobyoungi and Moabosaurus utahensis), demonstrating the survival of another 'basal' clade across the J/K boundary. Teeth from the Middle Jurassic-Early Cretaceous of western Europe and North Africa have also tentatively been attributed to turiasaurs, whilst recent phylogenetic analyses recovered Late Jurassic taxa from Argentina and China as further members of Turiasauria. Here, an anterior dorsal centrum and neural arch (both NHMUK 1871) from the Early Cretaceous Wealden Supergroup of the UK are described for the first time. NHMUK 1871 shares several synapomorphies with Turiasauria, especially the turiasaurs Moabosaurus and Tendaguria, including: (1) a strongly dorsoventrally compressed centrum; (2) the retention of prominent epipophyses; and (3) an extremely low, non-bifid neural spine. NHMUK 1871 therefore represents the first postcranial evidence for Turiasauria from European deposits of Early Cretaceous age. Although turiasaurs show clear heterodont dentition, only broad, characteristically 'heart'-shaped teeth can currently be attributed to Turiasauria with confidence. As such, several putative turiasaur occurrences based on isolated teeth from Europe, as well as the Middle Jurassic and Early Cretaceous of Africa, cannot be confidently referred to Turiasauria. Unequivocal evidence for turiasaurs is therefore restricted to the late Middle Jurassic-Early Cretaceous of western Europe, the Late Jurassic of Tanzania, and the late Early Cretaceous of the USA, although remains from elsewhere might ultimately demonstrate that the group had a near-global distribution. [ABSTRACT FROM AUTHOR]

Despite being globally widespread and abundant throughout much of the Mesozoic, the early record of sauropod dinosaur evolution is extremely poor. As such, any new remains can provide significant additions to our understanding of this important radiation. Here, we describe two sauropod middle cervical vertebrae from a new Early Jurassic locality in the Haute Moulouya Basin, Central High Atlas of Morocco. The possession of opisthocoelous centra, a well-developed system of centrodiapophyseal laminae, and the higher elevation of the postzygapophyses relative to the prezygapophyses, all provide strong support for a placement within Sauropoda. Absence of pneumaticity indicates non-neosauropod affinities, and several other features, including a tubercle on the dorsal margin of the prezygapophyses and an anteriorly slanting neural spine, suggest close relationships with various basal eusauropods, such as the Middle Jurassic taxa Jobaria tiguidensis and Patagosaurus fariasi. Phylogenetic analyses also support a position close to the base of Eusauropoda. The vertebrae differ from the only other Early Jurassic African sauropod dinosaurs preserving overlapping remains (the Moroccan Tazoudasaurus naimi and South African Pulanesaura eocollum), as well as stratigraphically younger taxa, although we refrain from erecting a new taxon due to the limited nature of the material. These new specimens represent one of the earliest eusauropod taxa and are an important additional data point for elucidating the early evolution of the clade. [ABSTRACT FROM AUTHOR]

ABSTRACT The Late Jurassic to Early Cretaceous interval represents a time of environmental upheaval and cataclysmic events, combined with disruptions to terrestrial and marine ecosystems. Historically, the Jurassic/ Cretaceous ( J/ K) boundary was classified as one of eight mass extinctions. However, more recent research has largely overturned this view, revealing a much more complex pattern of biotic and abiotic dynamics than has previously been appreciated. Here, we present a synthesis of our current knowledge of Late Jurassic-Early Cretaceous events, focusing particularly on events closest to the J/ K boundary. We find evidence for a combination of short-term catastrophic events, large-scale tectonic processes and environmental perturbations, and major clade interactions that led to a seemingly dramatic faunal and ecological turnover in both the marine and terrestrial realms. This is coupled with a great reduction in global biodiversity which might in part be explained by poor sampling. Very few groups appear to have been entirely resilient to this J/ K boundary 'event', which hints at a 'cascade model' of ecosystem changes driving faunal dynamics. Within terrestrial ecosystems, larger, more-specialised organisms, such as saurischian dinosaurs, appear to have suffered the most. Medium-sized tetanuran theropods declined, and were replaced by larger-bodied groups, and basal eusauropods were replaced by neosauropod faunas. The ascent of paravian theropods is emphasised by escalated competition with contemporary pterosaur groups, culminating in the explosive radiation of birds, although the timing of this is obfuscated by biases in sampling. Smaller, more ecologically diverse terrestrial non-archosaurs, such as lissamphibians and mammaliaforms, were comparatively resilient to extinctions, instead documenting the origination of many extant groups around the J/ K boundary. In the marine realm, extinctions were focused on low-latitude, shallow marine shelf-dwelling faunas, corresponding to a significant eustatic sea-level fall in the latest Jurassic. More mobile and ecologically plastic marine groups, such as ichthyosaurs, survived the boundary relatively unscathed. High rates of extinction and turnover in other macropredaceous marine groups, including plesiosaurs, are accompanied by the origin of most major lineages of extant sharks. Groups which occupied both marine and terrestrial ecosystems, including crocodylomorphs, document a selective extinction in shallow marine forms, whereas turtles appear to have diversified. These patterns suggest that different extinction selectivity and ecological processes were operating between marine and terrestrial ecosystems, which were ultimately important in determining the fates of many key groups, as well as the origins of many major extant lineages. We identify a series of potential abiotic candidates for driving these patterns, including multiple bolide impacts, several episodes of flood basalt eruptions, dramatic climate change, and major disruptions to oceanic systems. The J/ K transition therefore, although not a mass extinction, represents an important transitional period in the co-evolutionary history of life on Earth. [ABSTRACT FROM AUTHOR]

Highlights: [•] The latitudinal biodiversity gradient has not been a persistent feature through time. [•] The modern pattern might only have originated 30 million years ago. [•] A temperate diversity peak is recorded during warmer intervals. [•] A tropical diversity peak might characterise icehouse worlds. [ABSTRACT FROM AUTHOR]

Abstract: We use newly compiled data on global occurrences of Cretaceous lepidosaurs, mammals and crocodylomorphs, and existing data on dinosaurs, to investigate faunal turnover and fossil record heterogeneity. Statistically significant relationships between many clade-specific fossil record sampling proxies within major continental areas (e.g. European mammal-bearing formations) suggest that temporal patterns of fossil record sampling intensity of the most abundant tetrapod clades are similar to each other, with a few exceptions that might reflect clade-specific facies preferences or differences in worker effort (especially in poorly-sampled regions such as Gondwana). However, the absence of strong statistical relationships between tetrapod sampling proxies from different continental areas suggests that there is no unified ‘global’ sampling signal for terrestrial tetrapods. The Cretaceous witnessed substantial faunal turnover and the rise of many ‘advanced’ clades that today dominate terrestrial faunas. Despite strong spatiotemporal heterogeneity in sampling of the Cretaceous tetrapod record, it is clear that this transition occurred in a spatiotemporally staggered fashion. Thus, it cannot be attributed to a temporally localised early Late Cretaceous (Cenomanian–Turonian) extinction event. Many advanced clades, including eutherian mammals, iguanian and gekkotan squamates, and the main cryptodiran turtle crown clades first appeared, or first attained high fossil diversities, in Asia. However, relatively poor sampling and dating of ‘middle’ Cretaceous terrestrial deposits means that hypotheses of Asian, rather than Laurasian, diversifications remain tentative. Differences between Gondwanan and Laurasian faunas became progressively greater during the Cretaceous, and although many Gondwanan clades survived the end-Cretaceous extinction event, these only survive to the present as relictual populations with narrow geographic ranges (e.g. monotremes and rhynchocephalians). [Copyright &y& Elsevier]

Many palaeobiological analyses have concluded that modern birds (Neornithes) radiated no earlier than the Maastrichtian, whereas molecular clock studies have argued for a much earlier origination. Here, we assess the quality of the fossil record of Mesozoic avian species, using a recently proposed character completeness metric which calculates the percentage of phylogenetic characters that can be scored for each taxon. Estimates of fossil record quality are plotted against geological time and compared to estimates of species level diversity, sea level, and depositional environment. Geographical controls on the avian fossil record are investigated by comparing the completeness scores of species in different continental regions and latitudinal bins. Avian fossil record quality varies greatly with peaks during the Tithonian-early Berriasian, Aptian, and Coniacian-Santonian, and troughs during the Albian-Turonian and the Maastrichtian. The completeness metric correlates more strongly with a 'sampling corrected' residual diversity curve of avian species than with the raw taxic diversity curve, suggesting that the abundance and diversity of birds might influence the probability of high quality specimens being preserved. There is no correlation between avian completeness and sea level, the number of fluviolacustrine localities or a recently constructed character completeness metric of sauropodomorph dinosaurs. Comparisons between the completeness of Mesozoic birds and sauropodomorphs suggest that small delicate vertebrate skeletons are more easily destroyed by taphonomic processes, but more easily preserved whole. Lagerstätten deposits might therefore have a stronger impact on reconstructions of diversity of smaller organisms relative to more robust forms. The relatively poor quality of the avian fossil record in the Late Cretaceous combined with very patchy regional sampling means that it is possible neornithine lineages were present throughout this interval but have not yet been sampled or are difficult to identify because of the fragmentary nature of the specimens. [ABSTRACT FROM AUTHOR]

Abstract: Rebbachisauridae is a poorly understood clade of diplodocoid sauropod dinosaurs, currently known only from the Cretaceous of Africa, Europe and South America. European representatives are particularly rare and fragmentary. Here, we report an anterior caudal vertebra from the Barremian (Early Cretaceous) Wessex Formation of the Isle of Wight, off the southern coast of England. This specimen possesses several features known only in rebbachisaurids and shares two synapomorphies with the Afro-European taxa Demandasaurus darwini and Nigersaurus taqueti, both pertaining to the morphology of the neural spine. These features are the development of triangular lateral processes and the presence of an elliptical fossa on the lateral surface, bounded by the lateral lamina and postspinal rugosity. The Isle of Wight specimen also shares several features solely with Demandasaurus, indicating a close relationship with the Spanish taxon. These include the presence of a hyposphenal ridge, as well as an anteriorly excavated caudal rib that is restricted almost entirely to the neural arch. However, it differs from Demandasaurus in a number of ways, including the lack of excavation on the posterior surface of the caudal rib, the orientation of the neural spine, and the composition and morphology of the lateral lamina. In addition, the Isle of Wight vertebra possesses one potential autapomorphy: bifurcation of the elliptical fossa on the neural spine. However, because of the fragmentary nature of the material, a new name is not erected. Along with Demandasaurus and Histriasaurus boscarollii, this caudal vertebra indicates the presence of at least three European rebbachisaurid taxa and provides new anatomical information on this enigmatic clade of sauropod dinosaurs. [Copyright &y& Elsevier]

Titanosauria is a taxonomically and morphologically diverse clade of sauropod dinosaurs that appeared in the Middle Jurassic and radiated in the mid-Late Cretaceous; however, its intrarelationships are poorly understood. The mid-Cretaceous Argentinean sauropod Andesaurus delgadoi has repeatedly been recovered at the base of Titanosauria, and thus represents a crucial taxon for determining the evolutionary history of this clade; yet it has only received a brief description. Here, we re-describe the holotype, comprising dorsal, sacral, and caudal vertebrae, as well as limb and pelvic elements. Detailed comparisons are made with a global array of titanosauriforms. Andesaurus is a valid genus and can be diagnosed by five autapomorphies: (1) posterior dorsal neural spine height greater than twice centrum height (autapomorphic within Macronaria); (2) square-shaped anterior-middle caudal centra in lateral view; (3) anteroposteriorly elongate fossa present on the anterodorsal corner of the lateral surface of middle-posterior caudal centra; (4) ridge along the midshaft of the ventral surface of metacarpal I, close to the ventromedial margin; (5) prominent ventromedial ridge along the distal half of metacarpal V. Other remains previously attributed to Andesaurus cannot be referred to this genus. Sixteen putative titanosaur synapomorphies can be recognized in Andesaurus, including: (1) lateral pneumatic foramina in dorsal vertebrae situated within fossae; (2) anterior-middle caudal vertebrae with ventrolateral ridges either side of a ventral midline hollow; and (3) lateral bowing of metacarpal I. This revision provides an important foundation for future phylogenetic analyses of titanosaurs, and adds to our growing understanding of this enigmatic clade. Lastly, we recommend the disuse of the coordinated suprageneric rank taxa of Andesaurus (Andesaurinae, Andesauridae, and Andesauroidea), at least until titanosaur intrarelationships are better elucidated. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011. [ABSTRACT FROM AUTHOR]

The sauropod dinosaur ‘ Bothriospondylus’, originally named on the basis of Late Jurassic remains from England, is demonstrated to be invalid, and the characters used to diagnose it are shown to be obsolescent features which are widespread throughout Sauropoda. Material referred to this genus spans a temporal range from the Middle Jurassic until the early Late Cretaceous and has been described from five different countries, across three continents. These remains represent a wide array of sauropod groups, comprising non-neosauropod eusauropods, a macronarian, titanosauriforms (including at least one definite brachiosaurid) and a rebbachisaurid. The type material of the Middle Jurassic ‘ B. madagascariensis’ represents a derived non-neosauropod eusauropod and possesses two potential autapomorphies. However, as a result of the fragmentary nature of the material and the uncertainty surrounding its association, a new taxon is not erected. Of the numerous specimens referred to ‘ Bothriospondylus’, however, several remains are considered diagnostic: Ornithopsis hulkei (Early Cretaceous, UK), Lapparentosaurus madagascariensis (Middle Jurassic, Madagascar) and Nopcsaspondylus alarconensis (early Late Cretaceous, Argentina). At least three types of sauropod were present in the Bathonian (Middle Jurassic) of north-west Madagascar, with a basal eusauropod ( Archaeodontosaurus), a more derived eusauropod (‘ B. madagascariensis’) and a titanosauriform ( Lapparentosaurus) all approximately contemporaneous. Palaeocontinental reconstructions suggest that Middle Jurassic Madagascan sauropods would still have been capable of global biotic interchange, and this is perhaps reflected in their diverse assemblage. Re-evaluation of these Malagasy forms has shed new light on this important time period in sauropod evolution. [ABSTRACT FROM AUTHOR]

An isolated anterior caudal vertebra from the Qingshan (= Ch'ing shan) Formation (Early Cretaceous) of Shandong Province, China, is redescribed and shown to be an advanced diplodocid sauropod. This specimen possesses several derived character states that are typically observed in advanced diplodocoids or diplodocids, including the following: a mildly procoelous centrum; a deep pit-like pneumatic fossa immediately below the caudal rib; wing- or fan-shaped caudal ribs; and complex lamination of the neural spine. The neural spine is apomorphically short and the centrum is short relative to its height compared to those of other diplodocids, which, when coupled with the specimen’s unique geographical location and stratigraphical age, suggests that it probably represents a new taxon. This caudal vertebra provides the first convincing evidence that diplodocids were present in Asia, perhaps as a result of the dispersal of neosauropod lineages from Europe and/or North America during the Early Cretaceous. The discovery of a member of the Diplodocidae in the Early Cretaceous also indicates that this clade did not become extinct at the Jurassic/Cretaceous boundary as previously supposed. [ABSTRACT FROM AUTHOR]

Although sauropod dinosaur bones are the most abundant vertebrate fossils found in the Upper Cretaceous Winton Formation of northeast Australia, only subadult and adult specimens have been described to date. Herein, we describe the first juvenile sauropod from Australia, derived from the Winton Formation (Cenomanian–lower Turonian). The preserved material belongs to a single individual and is sufficiently diagnostic to classify as a juvenile Diamantinasaurus matildae—the third specimen to be referred to the species. It also enables the identification of a new local autapomorphy for Diamantinasaurus: a distinct tuberosity on the medial surface of the scapula, posterior to the junction of the acromion and the distal blade. Nevertheless, several morphological changes are observable between the juvenile and the two adult skeletons of Diamantinasaurus matildae. These include less well-defined or entirely absent muscle attachment sites on the juvenile bones relative to the heavily scarred and rugose adult specimens. Overlapping elements between the juvenile and the two adult skeletons indicate allometric changes for Diamantinasaurus matildae throughout ontogeny, with limb bones growing at a more rapid proportional rate than other skeletal elements. Finally, we review the global record of juvenile sauropod remains, demonstrating that the growth patterns of sauropods vary greatly between taxa. Although titanosaurs display a range of isometry and allometry in the growth of individual bones, it appears that allometric growth was the primary pattern for this group. [ABSTRACT FROM AUTHOR]