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  • JOURNAL ARTICLE
    Tennant JP, Mannion PD, Upchurch P, Sutton MD, Price GD, Tennant JP, Mannion PD, Upchurch P, Sutton MD, Price GD, Tennant JP, Mannion PD, Upchurch P, Sutton MD, Price GD, Tennant JP, Mannion PD, Upchurch P, Sutton MD, Price GD, Tennant JP, Mannion PD, Upchurch P, Sutton M, Price Get al., 2017,

    Biotic and environmental dynamics through the Late Jurassic-Early Cretaceous transition: evidence for protracted faunal and ecological turnover

    , BIOLOGICAL REVIEWS, Vol: 92, Pages: 776-814, ISSN: 1464-7931

    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, correspondi

  • JOURNAL ARTICLE
    Bates KT, Mannion PD, Falkingham PL, Brusatte SL, Hutchinson JR, Otero A, Sellers WI, Sullivan C, Stevens KA, Allen V, Bates KT, Mannion PD, Falkingham PL, Brusatte SL, Hutchinson JR, Otero A, Sellers WI, Sullivan C, Stevens KA, Allen V, Bates KT, Mannion PD, Falkingham PL, Brusatte SL, Hutchinson JR, Otero A, Sellers WI, Sullivan C, Stevens KA, Allen V, Bates KT, Mannion PD, Falkingham PL, Brusatte SL, Hutchinson JR, Otero A, Sellers WI, Sullivan C, Stevens KA, Allen V, Bates KT, Mannion PD, Falkingham PL, Brusatte SL, Hutchinson JR, Otero A, Sellers WI, Sullivan C, Stevens KA, Allen Vet al., 2016,

    Temporal and phylogenetic evolution of the sauropod dinosaur body plan

    , ROYAL SOCIETY OPEN SCIENCE, Vol: 3, Pages: 150636-150636, ISSN: 2054-5703

    The colossal size and body plan of sauropod dinosaurs are unparalleled in terrestrial vertebrates. However, to date, there have been only limited attempts to examine temporal and phylogenetic patterns in the sauropod bauplan. Here, we combine three-dimensional computational models with phylogenetic reconstructions to quantify the evolution of whole-body shape and body segment properties across the sauropod radiation. Limitations associated with the absence of soft tissue preservation in fossils result in large error bars about mean absolute body shape predictions. However, applying any consistent skeleton : body volume ratio to all taxa does yield changes in body shape that appear concurrent with major macroevolutionary events in sauropod history. A caudad shift in centre-of-mass (CoM) in Middle Triassic Saurischia, associated with the evolution of bipedalism in various dinosaur lineages, was reversed in Late Triassic sauropodomorphs. A craniad CoM shift coincided with the evolution of quadrupedalism in the Late Triassic, followed by a more striking craniad shift in Late Jurassic-Cretaceous titanosauriforms, which included the largest sauropods. These craniad CoM shifts are strongly correlated with neck enlargement, a key innovation in sauropod evolution and pivotal to their gigantism. By creating a much larger feeding envelope, neck elongation is thought to have increased feeding efficiency and opened up trophic niches that were inaccessible to other herbivores. However, we find that relative neck size and CoM position are not strongly correlated with inferred feeding habits. Instead the craniad CoM positions of titanosauriforms appear closely linked with locomotion and environmental distributions, potentially contributing to the continued success of this group until the end-Cretaceous, with all other sauropods having gone extinct by the early Late Cretaceous.

  • JOURNAL ARTICLE
    Benson RBJ, Butler RJ, Alroy J, Mannion PD, Carrano MT, Lloyd GT, Benson RBJ, Butler RJ, Alroy J, Mannion PD, Carrano MT, Lloyd GT, Benson RBJ, Butler RJ, Alroy J, Mannion PD, Carrano MT, Lloyd GT, Benson RBJ, Butler RJ, Alroy J, Mannion PD, Carrano MT, Lloyd GT, Benson RBJ, Butler RJ, Alroy J, Mannion PD, Carrano MT, Lloyd GTet al., 2016,

    Near-Stasis in the Long-Term Diversification of Mesozoic Tetrapods

    , PLOS BIOLOGY, Vol: 14, Pages: e1002359-e1002359, ISSN: 1545-7885

    How did evolution generate the extraordinary diversity of vertebrates on land? Zero species are known prior to ~380 million years ago, and more than 30,000 are present today. An expansionist model suggests this was achieved by large and unbounded increases, leading to substantially greater diversity in the present than at any time in the geological past. This model contrasts starkly with empirical support for constrained diversification in marine animals, suggesting different macroevolutionary processes on land and in the sea. We quantify patterns of vertebrate standing diversity on land during the Mesozoic-early Paleogene interval, applying sample-standardization to a global fossil dataset containing 27,260 occurrences of 4,898 non-marine tetrapod species. Our results show a highly stable pattern of Mesozoic tetrapod diversity at regional and local levels, underpinned by a weakly positive, but near-zero, long-term net diversification rate over 190 million years. Species diversity of non-flying terrestrial tetrapods less than doubled over this interval, despite the origins of exceptionally diverse extant groups within mammals, squamates, amphibians, and dinosaurs. Therefore, although speciose groups of modern tetrapods have Mesozoic origins, rates of Mesozoic diversification inferred from the fossil record are slow compared to those inferred from molecular phylogenies. If high speciation rates did occur in the Mesozoic, then they seem to have been balanced by extinctions among older clades. An apparent 4-fold expansion of species richness after the Cretaceous/Paleogene (K/Pg) boundary deserves further examination in light of potential taxonomic biases, but is consistent with the hypothesis that global environmental disturbances such as mass extinction events can rapidly adjust limits to diversity by restructuring ecosystems, and suggests that the gradualistic evolutionary diversification of tetrapods was punctuated by brief but dramatic episodes of radiation.

  • JOURNAL ARTICLE
    Chiarenza AA, Cau A, Chiarenza AA, Cau A, Chiarenza AA, Cau A, Chiarenza AA, Cau A, Chiarenza AA, Cau A, Chiarenza AA, Cau Aet al., 2016,

    A large abelisaurid (Dinosauria, Theropoda) from Morocco and comments on the Cenomanian theropods from North Africa

    , PEERJ, Vol: 4, Pages: e1754-e1754, ISSN: 2167-8359

    We describe the partially preserved femur of a large-bodied theropod dinosaur from the Cenomanian "Kem Kem Compound Assemblage" (KKCA) of Morocco. The fossil is housed in the Museo Geologico e Paleontologico "Gaetano Giorgio Gemmellaro" in Palermo (Italy). The specimen is compared with the theropod fossil record from the KKCA and coeval assemblages from North Africa. The combination of a distally reclined head, a not prominent trochanteric shelf, distally placed lesser trochanter of stout, alariform shape, a stocky shaft with the fourth trochanter placed proximally, and rugose muscular insertion areas in the specimen distinguishes it from Carcharodontosaurus, Deltadromeus and Spinosaurus and supports referral to an abelisaurid. The estimated body size for the individual from which this femur was derived is comparable to Carnotaurus and Ekrixinatosaurus (up to 9 meters in length and 2 tons in body mass). This find confirms that abelisaurids had reached their largest body size in the "middle Cretaceous," and that large abelisaurids coexisted with other giant theropods in Africa. We review the taxonomic status of the theropods from the Cenomanian of North Africa, and provisionally restrict the Linnean binomina Carcharodontosaurus iguidensis and Spinosaurus aegyptiacus to the type specimens. Based on comparisons among the theropod records from the Aptian-Cenomanian of South America and Africa, a partial explanation for the so-called "Stromer's riddle" (namely, the coexistence of many large predatory dinosaurs in the "middle Cretaceous" record from North Africa) is offered in term of taphonomic artifacts among lineage records that were ecologically and environmentally non-overlapping. Although morphofunctional and stratigraphic evidence supports an ecological segregation between spinosaurids and the other lineages, the co-occurrence of abelisaurids and carcharodontosaurids, two groups showing several craniodental converge

  • JOURNAL ARTICLE
    Dean CD, Mannion PD, Butler RJ, Dean CD, Mannion PD, Butler RJ, Dean CD, Mannion PD, Butler RJ, Dean CD, Mannion PD, Butler RJ, Dean D, Mannion PD, Butler RJet al., 2016,

    Preservational bias controls the fossil record of pterosaurs

    , PALAEONTOLOGY, Vol: 59, Pages: 225-247, ISSN: 0031-0239

    Pterosaurs, a Mesozoic group of flying archosaurs, have become a focal point for debates pertaining to the impact of sampling biases on our reading of the fossil record, as well as the utility of sampling proxies in palaeodiversity reconstructions. The completeness of the pterosaur fossil specimens themselves potentially provides additional information that is not captured in existing sampling proxies, and might shed new light on the group's evolutionary history. Here we assess the quality of the pterosaur fossil record via a character completeness metric based on the number of phylogenetic characters that can be scored for all known skeletons of 172 valid species, with averaged completeness values calculated for each geological stage. The fossil record of pterosaurs is observed to be strongly influenced by the occurrence and distribution of Lagerstätten. Peaks in completeness correlate with Lagerstätten deposits, and a recovered correlation between completeness and observed diversity is rendered non-significant when Lagerstätten species are excluded. Intervals previously regarded as potential extinction events are shown to lack Lagerstätten and exhibit low completeness values: as such, the apparent low diversity in these intervals might be at least partly the result of poor fossil record quality. A positive correlation between temporal patterns in completeness of Cretaceous pterosaurs and birds further demonstrates the prominent role that Lagerstätten deposits have on the preservation of smaller bodied organisms, contrasting with a lack of correlation with the completeness of large-bodied sauropodomorphs. However, we unexpectedly find a strong correlation between sauropodomorph and pterosaur completeness within the Triassic-Jurassic, but not the Cretaceous, potentially relating to a shared shift in environmental preference and thus preservation style through time. This study highlights the importance of understanding the relationship betwee

  • JOURNAL ARTICLE
    McPhee BW, Mannion PD, de Klerk WJ, Choiniere JN, McPhee BW, Mannion PD, de Klerk WJ, Choiniere JN, McPhee BW, Mannion PD, de Klerk WJ, Choiniere JNet al., 2016,

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

    , CRETACEOUS RESEARCH, Vol: 59, Pages: 228-248, ISSN: 0195-6671

    The Kirkwood Formation of South Africa has long been recognised 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.

  • JOURNAL ARTICLE
    Tennant JP, Mannion PD, Upchurch P, Tennant JP, Mannion PD, Upchurch P, Tennant JP, Mannion PD, Upchurch Pet al., 2016,

    Evolutionary relationships and systematics of Atoposauridae (Crocodylomorpha: Neosuchia): implications for the rise of Eusuchia

    , ZOOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Vol: 177, Pages: 854-936, ISSN: 0024-4082

    Atoposaurids are a group of small-bodied, extinct crocodyliforms, regarded as an important component of Jurassic and Cretaceous Laurasian semi-aquatic ecosystems. Despite the group being known for over 150 years, the taxonomic composition of Atoposauridae and its position within Crocodyliformes are unresolved. Uncertainty revolves around their placement within Neosuchia, in which they have been found to occupy a range of positions from the most basal neosuchian clade to more crownward eusuchians. This problem stems from a lack of adequate taxonomic treatment of specimens assigned to Atoposauridae, and key taxa such as Theriosuchus have become taxonomic ‘waste baskets’. Here, we incorporate all putative atoposaurid species into a new phylogenetic data matrix comprising 24 taxa scored for 329 characters. Many of our characters are heavily revised or novel to this study, and several ingroup taxa have never previously been included in a phylogenetic analysis. Parsimony and Bayesian approaches both recover Atoposauridae as a basal clade within Neosuchia, more stemward than coelognathosuchians, bernissartiids, and paralligatorids. Atoposauridae is a much more exclusive clade than previously recognized, comprising just three genera (Alligatorellus, Alligatorium, and Atoposaurus) that were restricted to the Late Jurassic of western Europe, and went extinct at the Jurassic/Cretaceous boundary. A putative Gondwanan atoposaurid (Brillanceausuchus) is recovered as a paralligatorid. Our results exclude both Montsecosuchus and Theriosuchus from Atoposauridae. Theriosuchus is polyphyletic, forming two groupings of advanced neosuchians. Theriosuchus (restricted to Theriosuchus pusillus, Theriosuchus guimarotae, and Theriosuchus grandinaris) spanned the Middle Jurassic to early Late Cretaceous, and is known from Eurasia and North Africa. Two Cretaceous species previously assigned to Theriosuchus (‘Theriosuchus’ ibericus and ‘Theriosuchus’ sympiest

  • JOURNAL ARTICLE
    Tennant JP, Mannion PD, Upchurch P, Tennant JP, Mannion PD, Upchurch P, Tennant JP, Mannion PD, Upchurch P, Tennant JP, Mannion PD, Upchurch P, Tennant JP, Mannion PD, Upchurch Pet al., 2016,

    Environmental drivers of crocodyliform extinction across the Jurassic/Cretaceous transition

    , PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 283, Pages: 20152840-20152840, ISSN: 0962-8452

    Crocodyliforms have a much richer evolutionary history than represented by their extant descendants, including several independent marine and terrestrial radiations during the Mesozoic. However, heterogeneous sampling of their fossil record has obscured their macroevolutionary dynamics, and obfuscated attempts to reconcile external drivers of these patterns. Here, we present a comprehensive analysis of crocodyliform biodiversity through the Jurassic/Cretaceous (J/K) transition using subsampling and phylogenetic approaches and apply maximum-likelihood methods to fit models of extrinsic variables to assess what mediated these patterns. A combination of fluctuations in sea-level and episodic perturbations to the carbon and sulfur cycles was primarily responsible for both a marine and non-marine crocodyliform biodiversity decline through the J/K boundary, primarily documented in Europe. This was tracked by high extinction rates at the boundary and suppressed origination rates throughout the Early Cretaceous. The diversification of Eusuchia and Notosuchia likely emanated from the easing of ecological pressure resulting from the biodiversity decline, which also culminated in the extinction of the marine thalattosuchians in the late Early Cretaceous. Through application of rigorous techniques for estimating biodiversity, our results demonstrate that it is possible to tease apart the complex array of controls on diversification patterns in major archosaur clades.

  • BOOK CHAPTER
    Anderson RM, Di Fatta G, Liotta A, Agoulmine N, Agrawal G, Berthold MR, Bordini RH, Borgelt C, Boutaba R, Calzarossa MC, Cannataro M, Choudhary A, Cortes U, Dagiuklas T, De Turck F, De Vleeschauwer B, Demestichas P, Dhoedt B, Festor O, Fortino G, Friderikos V, Giunchiglia F, Gravier C, Guo Y, Hunter D, Karypis G, Krishnaswamy S, Limam N, Medhi D, Merani ML, Nürnberger A, Pardede E, Parthasarathy S, Gaspary LP, Ranc D, Sivakumar K, Stadler R, Stiller B, Strassner J, Syed A, Talia D, Urso MA, Van Der Meer S, Wolff R, Granville LZ, Allison PA, Briggs DEGet al., 2015,

    Preface

    , Taphonomy:releasing the data locked in the fossil record, Editors: Allison, Briggs, New York, Publisher: ROYAL SOC, Pages: Vii-x, ISBN: 9780769544090
  • CONFERENCE PAPER
    Balikova D, Maidment S, Muxworthy AR, 2015,

    The age of the Morrison Formation (Western Interior, USA): A Magnetostratigraphic Approach (poster)

    , Magnetic Interactions 2015
  • JOURNAL ARTICLE
    Bertazzo S, Maidment SCR, Kallepitis C, Fearn S, Stevens MM, Xie H-N, Bertazzo S, Maidment SCR, Kallepitis C, Fearn S, Stevens MM, Xie H-N, Bertazzo S, Maidment SCR, Kallepitis C, Fearn S, Stevens MM, Xie HN, Bertazzo S, Maidment SC, Kallepitis C, Fearn S, Stevens MM, Xie HN, Bertazzo S, Maidment SCR, Kallepitis C, Fearn S, Stevens MM, Xie H-N, Bertazzo S, Maidment S, Kallepitis C, Fearn S, Stevens MM, Xie HN, Maidment SCR, Bertazzo S, Kallepitis C, Fearn S, Stevens MM, Xie HNet al., 2015,

    Fibres and cellular structures preserved in 75-million-year-old dinosaur specimens (vol 6, 7352, 2015)

    , NATURE COMMUNICATIONS, Vol: 6, Pages: 7352-7352, ISSN: 2041-1723

    Exceptionally preserved organic remains are known throughout the vertebrate fossil record, and recently, evidence has emerged that such soft tissue might contain original components. We examined samples from eight Cretaceous dinosaur bones using nano-analytical techniques; the bones are not exceptionally preserved and show no external indication of soft tissue. In one sample, we observe structures consistent with endogenous collagen fibre remains displaying ∼ 67 nm banding, indicating the possible preservation of the original quaternary structure. Using ToF-SIMS, we identify amino-acid fragments typical of collagen fibrils. Furthermore, we observe structures consistent with putative erythrocyte remains that exhibit mass spectra similar to emu whole blood. Using advanced material characterization approaches, we find that these putative biological structures can be well preserved over geological timescales, and their preservation is more common than previously thought. The preservation of protein over geological timescales offers the opportunity to investigate relationships, physiology and behaviour of long extinct animals.

  • JOURNAL ARTICLE
    Brusatte SL, Butler RJ, Barrett PM, Carrano MT, Evans DC, Lloyd GT, Mannion PD, Norell MA, Peppe DJ, Upchurch P, Williamson TE, Brusatte SL, Butler RJ, Barrett PM, Carrano MT, Evans DC, Lloyd GT, Mannion PD, Norell MA, Peppe DJ, Upchurch P, Williamson TE, Brusatte SL, Butler RJ, Barrett PM, Carrano MT, Evans DC, Lloyd GT, Mannion PD, Norell MA, Peppe DJ, Upchurch P, Williamson TE, Brusatte SL, Butler RJ, Barrett PM, Carrano MT, Evans DC, Lloyd GT, Mannion PD, Norell MA, Peppe DJ, Upchurch P, Williamson TE, Brusatte SL, Butler RJ, Barrett PM, Carrano MT, Evans DC, Lloyd GT, Mannion PD, Norell MA, Peppe DJ, Williamson TEet al., 2015,

    The extinction of the dinosaurs

    , BIOLOGICAL REVIEWS, Vol: 90, Pages: 628-642, ISSN: 1464-7931

    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.

  • JOURNAL ARTICLE
    Chiarenza AA, Foffa D, Young MT, Insacco G, Cau A, Carnevale G, Catanzariti R, Chiarenza AA, Foffa D, Young MT, Insacco G, Cau A, Carnevale G, Catanzariti Ret al., 2015,

    The youngest record of metriorhynchid crocodylomorphs, with implications for the extinction of Thalattosuchia

    , Cretaceous Research, Vol: 56, Pages: 608-616, ISSN: 0195-6671

    © 2015 Elsevier Ltd. Here we describe an isolated tooth of a metriorhynchid crocodylomorph from the Hybla Formation (Aptian, Lower Cretaceous) of Rocca Chi Parra quarry (Montagna Grande, Calatafimi, Trapani Province), Sicily, Italy. The specimen shares with the Upper Jurassic taxon Plesiosuchus manselii a mediolaterally compressed conical tooth crown, noticeable lingual curvature, mesial and distal carinae with microscopic, rectangular contiguous denticles, strong distal curvature of the mesial margin, and the presence of weak 'carinal flanges' on the labial and lingual surfaces (which are preeminent at the mid-crown). This suite of morphologies is also present in an unnamed Valanginian (Lower Cretaceous) plesiosuchinan from France. However, the Sicilian tooth differs from these taxa in having more pronounced carinae, and faint apicobasally aligned enamel ridges. It also differs from P.manselii in having more extensive 'carinal flanges' on the labial surface. The specimen extends the known geological range of Metriorhynchidae and Thalattosuchia by approximately 7-8 million years. This overturns previous hypotheses of Metriorhynchidae becoming extinct early in the Early Cretaceous.

  • JOURNAL ARTICLE
    Dean CD, Sutton MD, Siveter DJ, Siveter DJ, Dean CD, Sutton MD, Siveter DJ, Siveter DJet al., 2015,

    A novel respiratory architecture in the Silurian mollusc Acaenoplax

    , PALAEONTOLOGY, Vol: 58, Pages: 839-847, ISSN: 0031-0239
  • JOURNAL ARTICLE
    Jacobs CT, Goldin TJ, Collins GS, Piggott MD, Kramer SC, Melosh HJ, Wilson CRG, Allison PA, Jacobs CT, Goldin TJ, Collins GS, Piggott MD, Kramer SC, Melosh HJ, Wilson CRG, Allison PA, Jacobs CT, Goldin TJ, Collins GS, Piggott MD, Kramer SC, Melosh HJ, Wilson CRG, Allison PAet al., 2015,

    An improved quantitative measure of the tendency for volcanic ash plumes to form in water: implications for the deposition of marine ash beds

    , JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, Vol: 290, Pages: 114-124, ISSN: 0377-0273

    © 2014. Laboratory experiments and numerical simulations have shown that volcanic ash particles immersed in water can either settle slowly and individually, or rapidly and collectively as particle-laden plumes. The ratio of timescales for individual and collective settling, in the form of analytical expressions, provides a dimensionless quantitative measure of the tendency for such plumes to grow and persist which has important implications for determining particle residence times and deposition rates. However, existing measures in the literature assume that collective settling obeys Stokes' law and is therefore controlled by the balance between gravitational forces and viscous drag, despite plume development actually being controlled by the balance between gravitational forces and inertial drag even in the absence of turbulence during early times. This paper presents a new measure for plume onset which takes into account the inertial drag-controlled (rather than viscous drag-controlled) nature of plume growth and descent. A parameter study comprising a set of numerical simulations of small-scale volcanic ash particle settling experiments highlights the effectiveness of the new measure and, by comparison with an existing measure in the literature, also demonstrates that the timescale of collective settling is grossly under-estimated when assuming that plume development is slowed by viscous drag. Furthermore, the formulation of the new measure means that the tendency for plumes to form can be estimated from the thickness and concentration of the final deposit; the magnitude and duration of particle flux across the water's surface do not need to be known. The measure therefore permits the residence times of particles in a large body of water to be more accurately and practically determined, and allows the improved interpretation of layers of volcaniclastic material deposited at the seabed.

  • JOURNAL ARTICLE
    Jordan N, Allison PA, Hill J, Sutton MD, Jordan N, Allison PA, Hill J, Sutton MD, Jordan N, Allison PA, Hill J, Sutton MDet al., 2015,

    Not all aragonitic molluscs are missing: taphonomy and significance of a unique shelly lagerstatte from the Jurassic of SW Britain

    , LETHAIA, Vol: 48, Pages: 540-548, ISSN: 0024-1164

    The Blue Lias Formation at Lyme Regis (Dorset, UK) includes an exceptional pavement of abundant large ammonites that accumulated during a period of profound sedimentary condensation. Ammonites were originally composed of aragonite, an unstable polymorph of calcium carbonate, and such fossils are typically prone to dissolution; the occurrence of a rich association of aragonitic shells in a condensed bed is highly unusual. Aragonite dissolution occurs when pore-water pH is reduced by the oxidization of hydrogen sulphide close to the sediment-water interface. Evidence suggests that, in this case, the oxygen concentrations in the overlying water column were low during deposition. This inhibited the oxidation of sulphides and the associated lowering of pH, allowing aragonite to survive long enough for the shell to be neomorphosed to calcite. The loss of aragonite impacts upon estimates of past biodiversity and carbonate accumulation rates. The preservational model presented here implies that diagenetic loss of aragonite will be greatest in those areas where dysoxic-anoxic sediment lies beneath an oxic waterbody but least where the sediment and overlying water are oxygen depleted. Unfortunately, this implies that preservational bias through aragonite loss will be greatest in those biotopes which are typically most diverse and least where biodiversity is lowest due to oxygen restriction.

  • JOURNAL ARTICLE
    Mannion PD, Benson RBJ, Carrano MT, Tennant JP, Judd J, Butler RJ, Mannion PD, Benson RBJ, Carrano MT, Tennant JP, Judd J, Butler RJ, Mannion PD, Benson RB, Carrano MT, Tennant JP, Judd J, Butler RJ, Mannion PD, Benson RBJ, Carrano MT, Tennant JP, Judd J, Butler RJ, Mannion PD, Benson RBJ, Carrano MT, Tennant JP, Judd J, Butler RJet al., 2015,

    Climate constrains the evolutionary history and biodiversity of crocodylians

    , NATURE COMMUNICATIONS, Vol: 6, Pages: 8438-8438, ISSN: 2041-1723

    The fossil record of crocodylians and their relatives (pseudosuchians) reveals a rich evolutionary history, prompting questions about causes of long-term decline to their present-day low biodiversity. We analyse climatic drivers of subsampled pseudosuchian biodiversity over their 250 million year history, using a comprehensive new data set. Biodiversity and environmental changes correlate strongly, with long-term decline of terrestrial taxa driven by decreasing temperatures in northern temperate regions, and biodiversity decreases at lower latitudes matching patterns of increasing aridification. However, there is no relationship between temperature and biodiversity for marine pseudosuchians, with sea-level change and post-extinction opportunism demonstrated to be more important drivers. A 'modern-type' latitudinal biodiversity gradient might have existed throughout pseudosuchian history, and range expansion towards the poles occurred during warm intervals. Although their fossil record suggests that current global warming might promote long-term increases in crocodylian biodiversity and geographic range, the 'balancing forces' of anthropogenic environmental degradation complicate future predictions.

  • JOURNAL ARTICLE
    Martin-Short R, Hill J, Kramer SC, Avdis A, Allison PA, Piggott MD, Martin-Short R, Hill J, Kramer SC, Avdis A, Allison PA, Piggott MD, Martin-Short R, Hill J, Kramer SC, Avdis A, Allison PA, Piggott MD, Martin-Short R, Hill J, Kramer SC, Avdis A, Allison PA, Piggott MDet al., 2015,

    .Tidal resource extraction in the Pentland Firth, UK: Potential impacts on flow regime and sediment transport in the Inner Sound of Stroma

    , RENEWABLE ENERGY, Vol: 76, Pages: 596-607, ISSN: 0960-1481

    © 2014 The Authors. Large-scale extraction of power from tidal streams within the Pentland Firth is expected to be underway in the near future. The Inner Sound of Stroma in particular has attracted significant commercial interest. To understand potential environmental impacts of the installation of a tidal turbine array a case study based upon the Inner Sound is considered. A numerical computational fluid dynamics model, Fluidity, is used to conduct a series of depth-averaged simulations to investigate velocity and bed shear stress changes due to the presence of idealised tidal turbine arrays. The number of turbines is increased from zero to 400. It is found that arrays in excess of 85 turbines have the potential to affect bed shear stress distributions in such a way that the most favourable sites for sediment accumulation migrate from the edges of the Inner Sound towards its centre. Deposits of fine gravel and coarse sand are indicated to occur within arrays of greater than 240 turbines with removal of existing deposits in the shallower channel margins also possible. The effects of the turbine array may be seen several kilometres from the site which has implications not only on sediment accumulation, but also on the benthic fauna.

  • JOURNAL ARTICLE
    Poropat SF, Mannion PD, Upchurch P, Hocknull SA, Kear BP, Elliott DA, Poropat SF, Mannion PD, Upchurch P, Hocknull SA, Kear BP, Elliott DA, Poropat SF, Mannion PD, Upchurch P, Hocknull SA, Kear BP, Elliott DAet al., 2015,

    REASSESSMENT OF THE NON-TITANOSAURIAN SOMPHOSPONDYLAN WINTONOTITAN WATTSI (DINOSAURIA: SAUROPODA: TITANOSAURIFORMES) FROM THE MID-CRETACEOUS WINTON FORMATION, QUEENSLAND, AUSTRALIA

    , PAPERS IN PALAEONTOLOGY, Vol: 1, Pages: 59-106, ISSN: 2056-2799
  • JOURNAL ARTICLE
    Poropat SF, Upchurch P, Mannion PD, Hocknull SA, Kear BP, Sloan T, Sinapius GHK, Elliott DA, Poropat SF, Upchurch P, Mannion PD, Hocknull SA, Kear BP, Sloan T, Sinapius GHK, Elliott DA, Poropat SF, Upchurch P, Mannion PD, Hocknull SA, Kear BP, Sloan T, Sinapius GHK, Elliott DAet al., 2015,

    Revision of the sauropod dinosaur Diamantinasaurus matildae Hocknull et al. 2009 from the mid-Cretaceous of Australia: Implications for Gondwanan titanosauriform dispersal

    , GONDWANA RESEARCH, Vol: 27, Pages: 995-1033, ISSN: 1342-937X

    The osteology of Diamantinasaurus matildae, the most complete Cretaceous sauropod described from Australia todate, is comprehensively reassessed. The preparation of additional material from the type locality, pertaining tothe same individual as the holotype, sheds light on the morphology of the axial skeleton and provides additionalinformation on the appendicular skeleton. The new material comprises two dorsal vertebrae, an incompletesacrum (including four partial coalesced vertebrae), the right coracoid, the right radius, an additional manualphalanx, and a previously missing portion of the right fibula. In this study we identify thirteen autapomorphiccharacters of Diamantinasaurus, and an additional five characters that are locally autapomorphic withinTitanosauriformes. This work provided an opportunity to revisit the phylogenetic placement of Diamantinasaurus.In two independent data matrices, Diamantinasaurus was recovered within Lithostrotia. One analysis resolvedDiamantinasaurus as the sister taxon to the approximately coeval Tapuiasaurus from Brazil, whereas the secondanalysis recovered Diamantinasaurus as the sister taxon to Opisthocoelicaudia from the latest Cretaceous ofMongolia. The characters supporting the recovered relationships are analysed, and the palaeobiogeographical implicationsof the lithostrotian status of Diamantinasaurus are explored. A brief review of the body fossil record ofAustralian Cretaceous terrestrial vertebrates suggests close ties to South America in particular, and to Gondwanamore generally.

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