A downloadable PDF version can be found here: Annual Meeting 2015 - Cardiff - Abstracts & Programme
Acanthomorphic acritarch pseudofossils in Ediacaran chert nodules from Oman
*Peter W. Adamson1,2, Gil Machado3,4 and Nicholas J. Butterfield1
1University of Cambridge, UK
2British Geological Survey, UK
3Universidade de Lisboa, Portugal
4Galp Energia E&P. Lisbon, Portugal
Chert permineralization provides an important taphonomic window into the diversity, ecology, and the spatial and temporal distribution of large acanthomorphic acritarchs in the Ediacaran. It is therefore important to critically assess diagenesis in chert-forming environments in order to identify diagenetic artefacts masquerading as biological characters. The occurrence of genuine acanthomorphs in the Ediacaran of Oman would have important implications for the understanding of Huqf stratigraphy, and Ediacaran biostratigraphy in general. Here we present an in-depth taphonomic analysis of a shallow marine carbonate environment with large, apparently acanthomorphic, acritarchs bearing long cylindrical or conical processes, preserved in chert nodules from the Khufai Formation (Huqf Supergroup) in Oman. However, petrographic analysis reveals that the apparently acanthomorphic features of the acritarchs are the result of early diagenetic precipitation of bladed and dog-tooth isopachous calcite cements on sphaeromorphic acritarch vesicles. Coating of these crystals by remobilized organic matter creates the illusion of acanthomorphic processes. These cements can generally be distinguished from acanthomorphic processes by their morphological inconsistency. This means partially or poorly preserved acritarchs – those most likely to experience diagenetic overgrowths – are also the most difficult to distinguish from pseudofossils. Understanding diagenesis in chert-permineralizing environments is therefore crucial for a robust Ediacaran microfossil record.
Prasinophyte world: biodiversity of organic-walled microfossils from the Tonian Visingsö Group, Lake Vättern, Sweden
*Heda Agić, Małgorzata Moczydłowska and Sebastian Willman
Uppsala University, Sweden
Diversification of eukaryotic, single-celled, organic-walled microorganisms reached its peak in the early Neoproterozoic. The Tonian Visingsö Group, southern Sweden, has yielded exceptionally-preserved palynomorphs, including fossils of characteristic prasinophyte morphologies. Microfossils were recovered from a drill core through the Visingsö Group, exposed on Visingsö island and the coast of Lake Vättern. Biostratigraphic correlation with isotopically-dated successions suggests the Visingsö strata were deposited ~740–800 Ma. The upper formation contains well-laminated, micaceous shales and is particularly fossiliferous. Microfossils were extracted by a standard palynological method, studied using light and scanning-electron microscopy, and compared to extant protists. Diversity increases upwards through the Visingsö succession, from spheroidal to ornamented morphotypes. The assemblage contains Pterospermopsimorpha, Simia, Tasmanites, Cerebrosphaera, Vandalosphaeridium, Trachysphaeridium, Chuaria, Kildinella, leiosphaerids and unnamed acanthomorphs. Certain microfossils share morphological characters with extant prasinophytes Pterosperma and Pachysphaera. Furthermore, presence of an envelope around a central body in some taxa is indicative of a phycoma: a resilient reproductive structure produced by present-day prasinophytes. Prasinophycean algae have a long evolutionary history, appearing in the Mesoproterozoic, and are poorly resolved. However, the order represented in the fossil record, Pyramimonadales, is monophyletic. Visingsö microfossils provide a detailed insight into the early evolution of this ancient algal group.
Extinction-related body size trends in Early Jurassic bivalves and brachiopods of northeastern Spain
Bethany J. Allen1, Richard J. Twitchett2 and Silvia Danise3
1Durham University, UK
2Natural History Museum, London, UK
3University of Georgia, USA
The Pliensbachian–Toarcian extinction event, attributed to global warming and associated environmental changes such as expanding oceanic anoxia, is recorded in marine assemblages worldwide. Published data indicate that marine molluscs underwent significant size changes during this event, including a temporary reduction in body size in some surviving taxa during the immediate post-extinction interval (i.e. the Lilliput effect). Such studies are, however, based on single locations and recorded size trends may simply reflect local depth- or facies-related changes. To address this, the body sizes of 763 individuals of 17 Pliensbachian–Toarcian benthic genera, collected by bulk sampling two different localities in northeastern Spain, were studied. Where possible, three linear dimensions were measured on each specimen, which were then used to calculate geometric mean size. Significant differences were found between the two localities, with larger body sizes in the shallower, better-oxygenated site. Body size trends within some individual taxa through the same interval of time recorded differences in direction or amplitude at the two localities. Interspecific differences in response were also recorded. These results suggest that even during major global change, differences in the local environment and ecology govern the biotic responses of marine organisms resulting in site-specific body size trends through time.
Microfossil communities preserved in Ediacaran cherts of the Shuurgat Formation, Zavkhan Terrane, southwestern Mongolia
*Ross P. Anderson1, Sean McMahon1, Uyanga Bold2, Francis A. Macdonald2 and Derek E. G. Briggs1
1Yale University, USA
2Harvard University, USA
Abundant microfossils are preserved within Cryogenian strata of the Taishir Formation (c. 660–635 Ma), southwestern Mongolia. Here we assess changes in microbial communities across the Marinoan snowball Earth ice age by analysing microfossils preserved in early diagenetic chert nodules from the overlying Ediacaran strata of the Shuurgat Formation. The Shuurgat Formation was deposited during early Ediacaran time: it conformably overlies a Marinoan cap carbonate in the basal Ol Formation and is overlain unconformably by the Zunne Arts Formation, which includes the Precambrian–Cambrian boundary. The fossiliferous chert nodules occur in subsidiary intraclast conglomerate horizons within the laminated micrite and calcisiltite upper portion of the Formation. Abundant fragments of organic material, which contain carbonaceous microfossils and may represent pieces of microbial mat, are preserved within the chert nodules. Spheroids, 5–20 µm in maximum dimension, some of which possess thick walls with internal detail, dominate the microfossil assemblage. Filaments are also well represented with morphologies including branched, unbranched, and septate forms. A vase-shaped microfossil (VSM), ~100 µm in maximum dimension, hints at the presence of unicellular eukaryotes. VSMs have previously only been reported in c. 850–720 Ma strata, and if confirmed, the new Shuurgat Formation VSMs represent the youngest Neoproterozoic occurrences yet discovered.
Two new odd Notosuchians from the Upper Cretaceous Bauru Group, Southeastern Brazil
Marco B. de Andrade1,2, Rodrigo M. Santucci3, William R. Nava4
1Pontifícia Universidade Católica do Rio Grande do Sul, Brazil
2Museu de Ciências e Tecnologia, PUCRS, Brazil
3Universidade de Brasília (Campus Planaltina), Brazil
4Museu de Paleontologia de Marilia, Brazil
Notosuchian crocodylomorphs are a key element in South American Mesozoic fossil assemblages, particularly in the Upper Cretaceous fossil record of Bauru Group, where crocodylomorphs currently comprise over 15 taxa, most of them belonging to Sphagesauridae, Baurusuchidae and Peirosauridae. Undescribed specimens from the vicinity of Marilia, Brazil indicate the existence of two new notosuchian taxa. The first one – a small fragment of maxilla with teeth – comes from the Araçatuba/Adamantina Formations (Campanian) and represents a new species of the small-sized Adamantinasuchus, characterized by the presence of an antorbital fenestra. The second specimen – a partial skull and mandible – comes from the Marilia Formation (Maastrichtian). It represents a medium-sized sphagesaurid, displaying the typical dentition and morphology of this family, alongside unexpected bizarre characteristics of the rostrum, narial opening and orbital region. Most of the notosuchian fauna of Bauru Group contrasts with other South American and African crocodylomorphs, with dentition and skull morphology dedicated to process food rather than to capture prey. The continual increase of diversity and disparity of Brazilian fossil crocodylomorphs in recent decades suggests that the collection effort carried out since the 1940s has so far only provided a glimpse of the exquisite past faunal assemblages, particularly in the Bauru sediments.
Palynological analysis of the Middle Devonian of northern Spain: hunting for the Kačák event
*Alexander J. Askew and Charles H. Wellman
University of Sheffield, UK
Northern Spain contains one of the most complete Devonian sequences in Western Europe chronicling widely varying depositional environments in a Peri-Gondwana setting. We describe palynomorph assemblages from the Eifelian and Givetian age Huergas, Naranco and Gustalapiedra Formations from Asturias, Castilla y León and Palencia provinces, respectively. These laterally equivalent formations represent a transect from shallow nearshore marine, across the shelf, to deep offshore shelf deposits. They are comprised of large sandstone bodies interspersed with black shales that are sandwiched between thick limestone sequences. Samples have been collected from long stratigraphic sections and yield rich assemblages of land-derived spores and marine palynomorphs (acritarchs, chitinozoans and occasional scolecodonts). The palynological assemblages have been quantitatively analysed to reveal changes in the terrestrial flora and marine biota through time and space. The Kačák event is a widely occurring anoxic event that occurs around the Eifelian/Givetian boundary and is associated with extinctions in the marine realm. This event is not well characterized in the Iberian Peninsula but is believed to be represented in the upper part of the Huergas, Naranco and Gustalapiedra Formations. We aim to identify the Kačák event in northern Spain and document its effect on both the marine phytoplankton and terrestrial biota.
Drifters, floaters or swimmers? Morphological evidence for functionally selective extinction in the Ammonoidea
Timothy Astrop1, Matthew Wills1, Michael Carley1, Qilong Ren1, Dieter Korn2 and Sylvain Gerber3
1University of Bath, UK
2Museum für Naturkunde, Germany
3University of Cambridge, UK
Of the major extinction events that the Ammonoidea survived, the Devonian/Carboniferous was arguably the most severe. The Ammonoidea had already been greatly winnowed by the mid-Frasnian Kellwasser event, which saw the near-extinction of most major lineages. Despite the rapid diversification of the Family Tornoceratidae and the Order Clymeniida in the 30 million years before the end of the Devonian, the Hangenberg bio-event brought the entire Subclass Ammonoidea to the brink of total extinction. The survival and radiation of a single Goniatite lineage subsequently saw much of the previous morphological diversity replaced by convergent forms. Here we utilize multiple approaches to elucidate possible morphological and functional factors that may have affected a lineage’s susceptibility and ability to recover from extinction events. We present a geometric morphometric methodology that enables us to describe detailed shape change trends in ammonoid conchs, and to do this throughout their ontogeny. These data, alongside three-dimensional scanning and printing technology, allow us to assess the hydrodynamic properties of different ammonite species at different ontogenetic stages, and for the first time, to make information-based inferences regarding their ontogeny, ecology and functional biology.
Testing biotic recovery from the early Toarcian (Lower Jurassic) extinction event
*Jed W. Atkinson and Crispin T. S. Little
University of Leeds, UK
The Toarcian oceanic anoxic event (TOAE) and associated marine mass extinction have attracted a great deal of research effort, focusing primarily on the causal mechanisms. In contrast, there is less known of the patterns of biotic recovery following this mass extinction (and others). Yet such recoveries are of interest as they record how surviving organisms radiate into newly vacated ecospace. The Cleveland Basin, North Yorkshire, has one of the most expanded Toarcian rock sections. Previous studies have presented a limited view of the recovery interval as the upper Toarcian sequence across much of the basin was truncated by a period of erosion during the Middle Jurassic. However, the Ravenscar coastal section preserves all of the upper Toarcian stratigraphy. We sampled 44m of this section and recorded 25,412 benthic and nektic macrofossils, giving us new range data, and allowing, for the first time, a full evaluation of the biotic recovery from the TOAE. Results show that the recovery interval was overprinted by a regressive marine sequence with pre-extinction levels of diversity attained and exceeded around 5 million years after the extinction horizon.
The overlooked crustaceans from Mount Lebanon
Denis Audo1,2, Sylvain Charbonnier2, Matúš Hyžný3 and Alessandro Garassino4
1Université de Rennes 1, France
2Muséum national d’Histoire naturelle, France
3Naturhistorisches Museum Wien, Austria
4Museo di Storia Naturale di Milano, Italy
In the Middle Ages, when Louis IX of France went to crusades, fossil fishes were discovered in Lebanon. Almost eight hundred years later, the very same outcrops continue to yield an impressive fauna and flora dated into the Cenomanian and Santonian. Among the animals, crustaceans are extremely diversified, yet still poorly studied. To address this problem, we propose the first comprehensive revision of all crustaceans from Lebanon. In this study, we describe or redescribe over 60 species of crustaceans: mantis shrimps, glass shrimps, diverse dendrobranchiate and caridean shrimps, glypheid lobsters, slipper lobsters, erymid lobsters, squat lobsters, crustacean larvae – including those of slipper, achelate and polychelidan lobsters. Most of these species are the first or last fossil occurrence of their respective group. The Lebanese outcrops also yield the last members of the enigmatic thylacocephalan arthropods, which affinities are still not resolved. Our study shows for the first time that Lebanese outcrops rival in terms of palaeobiodiversity all other Mesozoic outcrops. They offer a unique view to the palaeobiodiversity of crustaceans and will help to better understand the evolution of crustacean clades and the timing of their apparition.
Rock and roll: assessing the damage of turbulent flows on soft-bodied organisms
*Orla Bath Enright1, Nicholas J. Minter1, Esther J. Sumner2, M. Gabriela Mangáno3 and Luis Buatois3
1University of Portsmouth, UK
2University of Southampton, UK
3University of Saskatchewan, Canada
In the past, experimental taphonomy on exceptional preservation of soft-bodied organisms mostly focused on post-depositional factors, such as decay in static bodies of water. However, an underdeveloped aspect of this field of research is the sedimentological processes leading up to the entombment of fossil organisms in the first instance. This is especially significant for those from fossil Lagerstätten where organisms may be allochthonous, such as the Burgess Shale. This has important implications for interpreting the palaeoecology of these assemblages. It is therefore crucial to understand the effects of different sediment-density flow regimes on soft-bodied organisms. Here, through experimentation, we analyse the exact variables of turbulent flows that may have a detrimental effect on the polychaete, Alitta virens. Variables studied include the angularity of the grains, transport distance, and concentration of a flow in an annular flume tank. An index of ‘increasing state of damage’ has been devised to classify the amount of destruction each organism exhibits after the experimental procedure. Results of these experiments are discussed here.
Reconstructing the evolutionary history of the clade Pelagia
*Hermione Beckett and Matt Friedman
University of Oxford, UK
Pelagia is a disparate clade of open-ocean fishes recently identified through molecular studies. This group includes the economically important Scombridae (tunas and mackerels), which are characterized by exceptional anatomical innovations for efficient high-speed swimming. The ecologically distinct lineages of Pelagia appear to have diverged rapidly early in the group’s history. This conforms to concepts of ‘adaptive radiation’, but differs from classic examples like cichlids and Anolis lizards in both age and geographic scale. Although numerous well-preserved fossils have been aligned with Pelagia, these have not been integrated into a modern phylogenetic framework. Consequently, there is great uncertainty in the age of this radiation (molecular estimates disagree by 50 Ma) and the specific relationships between major sub-clades. Excellently preserved material from the UK, Angola and other sites provides an opportunity to investigate the evolutionary history of the group. We applied computed tomography (CT) to three-dimensionally preserved fossils historically attributed to this clade, including putative scombrids (Landanichthys, Scombrinus), gempylids and trichiurids (Eutrichiurides, Progempylus). Preliminary results suggest unexpected levels of trophic diversity in the earliest scombrids, as well as a need to re-examine the systematics of the diverse London Clay scombroid fauna. This will inform a larger morphological review of this clade.
Lamniform shark tooth morphometrics show a shift in community structure over the Cretaceous–Palaeogene mass extinction event
Rachel Belben1, Zerina Johanson1, Charlie Underwood2 and Richard Twitchett1
1Natural History Museum, London, UK
2Birkbeck, University of London, UK
Extinct lamniform shark teeth are abundant in the fossil record, but the significance of these to the study of the broader ecosystem is overlooked in the literature. In this study, shark tooth morphology, which in modern taxa corresponds to feeding behaviour and prey choice, is used as a proxy in fossil assemblages to suggest the feeding guilds and community structure present. Tooth morphology was quantified from two lamniform (mackerel shark) assemblages from Morocco, one from each side of the K/Pg boundary, as well as for a selection of morphologically diverse extant taxa. Principal component analysis (PCA) shows a dramatic shift in morphospace: the pre-extinction (Maastrichtian) morphospace has a range smaller than, but comparable to, that of the extant taxa, while the post-extinction (Danian) morphospace is much reduced. Across the K/Pg boundary there is a loss of tooth morphology extremes, including large, robust teeth, and broad serrated teeth. These data suggest that this marine ecosystem was highly impacted on an ecological basis, at apex-predator level, by the K/Pg extinction event. A loss of large, cutting-form and robust teeth suggests both a decrease in shark size, and the loss of large prey items.
Changes in mammal disparity across two fossil Lagerstätten sites from the Mesozoic and Cenozoic
*Gemma L. Benevento and Matt Friedman
University of Oxford, UK
Extant mammals exhibit a remarkable variety of forms and functions; however, they have not always shown such high levels of ecomorphological disparity. Mesozoic mammals are stereotyped as small ‘generalists’ or ‘insectivores’, only evolving novel forms as a result of an adaptive radiation at the K/Pg boundary. Shifts in the disparity of phenotypic traits in mammals from the Mesozoic to Cenozoic are not well quantified. Complicating matters is an emerging picture of surprisingly high levels of morphological disparity in Mesozoic mammals. In an attempt to better constrain patterns of mammal diversification, we quantified ecomorphological disparity in two Lagerstätten with a common lacustrine setting stratigraphically flanking the K/Pg boundary: the Cretaceous Jehol Biota and the Eocene Messel Pit. With a relative abundance of specimens yielding information on anatomical systems beyond dentition, functionally relevant continuous measurements for limbs and jaws, representing locomotor and feeding type respectively, can be collected. Preliminary results show mammals from these two sites do not show substantial differences in disparity in traits related to feeding ecology. Elevated locomotor disparity in Messel mammals can be attributed to a handful of groups with locomotor ecologies unknown from the Cretaceous: bats, early horses, and the genus Leptictidium, which may have been semi-bipedal.
Assessment of the Creswell Crags fossil material in the Nottingham Natural History Museum, Wollaton Hall, UK
*Jordan Bestwick1,2 and Adam S. Smith2
1University of Leicester, UK
2Nottingham Natural History Museum, UK
The Creswell Crags gorge on the Nottinghamshire–Derbyshire border contains a series of caves in which Holocene and Late Pleistocene deposits accumulated. The palaeontological significance of Creswell Crags was first recognized in the 1870s when a diverse fossil mammalian fauna was excavated from the cave deposits. This led to a large number of fossils being donated, sold or bequeathed to the Nottingham Natural History Museum, Wollaton Hall (NOTNH). This study provides the first investigation of the entire NOTNH Creswell Crags collection with respect to faunal abundances, how these proportions compare to historical excavations, and a review of the provenance data. Overall, the NOTNH contains 274 fossil specimens from Creswell Crags consisting of 466 individual elements, of which 61% have been identified to genus level. 17 genera have been identified from six orders: Carnivora, Artiodactyla, Perissodactyla, Proboscidea, Lagomorpha and Primata. The NOTNH collection contains proportionately more woolly rhino (Coelodonta) elements than the 1870s excavations but fewer hyaena (Crocuta), reindeer (Rangifer), and woolly mammoth (Mammuthus). We attribute these discrepancies to a possible ‘donation bias’. Only 10.1% of elements can be attributed to specific caves and none retain any detailed stratigraphic data. This compromises the overall scientific value of the collection.
What were they thinking? Exploring the potential of neurocranial anatomical studies throughout Ceratopsia
*C. Bullar1, M. J. Benton1, Q. Zhao2 and M. Ryan3
1University of Bristol, UK
2Institute of Vertebrate Paleontology and Paleoanthropology, China
3Cleveland Museum of Natural History, USA
The neurocranial anatomy of extinct organisms has always excited the palaeontological community. Since the 19th century, palaeontologists have been examining whether endocasts can provide a good resolution of brain size and morphology and, if so, what this can tell us about the sensory capacity of these long dead organisms. Ceratopsians were one of the most diverse dinosaurian clades of the Late Cretaceous and have a fantastic fossil record of basal forms in Asia. Ceratopsian palaeontology is currently lacking in comprehensive neuroanatomical studies. Analysis of ceratopsian neurological evolution will ultimately show how neurology likely affects behaviour, assumed through previous studies. This investigation offers the rare chance to study both basal Asian and North American taxa to enable analysis in a morphological and macroevolutionary context whilst creating an accessible set of braincase 3D PDFs. I present the preliminary study indicating what the palaeoneurology of Psittacosaurus lujiatunensis can tell us, and how this can be expanded to incorporate every major clade within Ceratopsia.
Traces on living slipper limpets Crepidula fornicata (L.)
Gerhard C. Cadée
Royal Netherlands Institute for Sea Research (NIOZ), The Netherlands
Slipper limpets were imported to the UK in ~1880 and invaded the Netherlands in ~1930. They are now abundant in the Wadden Sea, especially between the Pacific oysters flourishing here since ~1990. Slipper limpets are sessile suspension feeders living in chains. Herring gulls crush slippers by dropping them on the Wadden Sea dyke. On these the attachment scar of the limpet on top is easily visible. They hardly move after attachment, which leaves the area outside the attachment available for boring organisms. In the Wadden Sea this is mainly the boring polychaete Polydora. This drives the slipper to produce extra shell material (blisters) on the inside of its shell. These are well known in Polydora-infested mussels. Fossil attachment scars of Crepidula and the related Capulus were described as Lacrimichnos. Fossilization potential of these attachment traces is low, they are not mentioned amongst the many bioerosion traces on fossil Crepidula by Richiano et al. 2015.
Reconstructing the Middle Miocene palaeoenvironment of Quebrada Honda, Bolivia, using ichnology and palaeopedology
*Angeline M. Catena, Beverly Z. Saylor and Darin A. Croft
Case Western Reserve University, USA
The Neotropics contain exceptional levels of mammalian diversity, but few fossil-producing localities document the history of this fauna. La Venta, Colombia (LV), and Quebrada Honda, Bolivia (QH) are contemporaneous (13–12 Ma) sites that preserve the remains of many extinct Neotropical mammals. Almost no genera are shared between these localities, which could reflect habitat differences. Here we use palaeopedology and ichnology to elucidate the habitat of QH and test this hypothesis. The palaeosols of QH are weakly to moderately developed and composed of brown-to-red mudstones; they are interpreted as Entisols and Inceptisols. The ichnofossils include burrows with chambers, and horizons of Celliforma and Coprinisphaera; they are interpreted as breeding structures of solitary insects and dwelling structures of small mammals, respectively. Rhizoliths include rhizohaloes that are interpreted as roots of grasses and other small plants, and rhizocretions that are interpreted as taproots of medium to large plants such as shrubs and trees. The palaeosol and ichnofossil data from QH suggest a mixture of grasslands and savannahs located proximal to alluvial systems. This interpretation contrasts with published palaeoenvironmental interpretations for LV (river-associated tropical forests) and indicates that dissimilar habitats could account for many of the differences between the mammal faunas of these two fossil sites.
The Tournaisian: a sarcopterygian incubator?
Tom J. Challands1, Carys Bennett2, Jenny A. Clack3, Nick Fraser4, Tim Kearsey5, John E. A. Marshall6, Tim Smithson3 and Stig Walsh4
1University of Edinburgh, UK
2University of Leicester, UK
3University of Cambridge, UK
4National Museums Scotland, UK
5British Geological Survey, UK
6University of Southampton, UK
Once considered to be nearly devoid of vertebrates, Romer’s Gap is now being bridged as new material from the Tournaisian of northern England and the Scottish Borders reveals higher than anticipated diversity of fish and tetrapods from this period. New material from Tantallon, East Lothian, Scotland, from the upper Ballagan Formation (late Tournaisian) provides evidence of continued radiation throughout the Tournaisian. In particular, sarcopterygian taxa (represented predominantly by teeth), especially lungfish and rhizodonts, are abundant and diverse. The Tantallon material is, however, unusual in one very important aspect: most of it is very small. Recent bulk acid preparation and subsequent sorting has revealed a rich variety of micro fossils including lungfish tooth plates, rhizodont teeth and chondrichthyan teeth and scales, including forms not previously seen in the Ballagan Formation. This new material, along with other Tournaisian sites in the region, is beginning to dispel the myth that the post-Hangenberg world was a desolate sparsely-inhabited dystopia but rather one of rapid diversification in the Sarcopterygii that rapidly occupied newly available niches.
Lepidosaurian diversity through time: an exploratory look at the data
*Terri J. Cleary1,2
1Natural History Museum, London, UK
2University College London, UK
Lepidosauria comprises Rhynchocephalia (tuatara and extinct relatives) and Squamata (lizards, snakes and amphisbaenia). In the past both were geographically widespread, with a complicated history of radiation and extinction. While their diversity in certain periods has been examined, long-term patterns have not. Here I study the diversity of terrestrial lepidosaurs from the Triassic–Palaeogene (252–23 Ma) on genus-level occurrence data (1,418 specimens representing 332 genera) from the Paleobiology Database. Shareholder quorum subsampling is used to alleviate biases associated with raw diversity counts. At substantial quorum levels (>0.5), low diversity in the Late Triassic further declines across the Jurassic boundary. High diversity in the Late Cretaceous plummets between the Campanian and Maastrichtian, prior to the K/Pg extinction. A rise post-K/Pg represents radiation following the extinction of non-avian dinosaurs. Diversity falls again in the Late Eocene, recovering somewhat in the Oligocene; this may represent the “Grande Coupure” turnover event. Current data are highly American-centric: 41% of specimens are from the USA. Occurrences are concentrated in the Late Cretaceous and Eocene, likely representing intensive sampling; further data will be gathered to reduce these biases. More complete information can be used to examine potential drivers of diversity, and comprehensively assess bias in the lepidosaur record.
Livers, guts and gills: how decay profiles control the fossilization potential of soft tissues
*Thomas Clements, Mark Purnell and Sarah Gabbott
University of Leicester, UK
The interpretation of soft-bodied fossils is often contentious, especially in primitive or enigmatic fossil organisms where we have no modern analogues for comparative analysis. It is therefore of vital importance to understand the processes organisms undergo during the fossilization process, chief of which is decay. We have designed a series of novel experiments to investigate in real time how decay processes affect the fossilization potential of specific internal soft-tissues. Our data will allow us to unravel the timing and sequence of internal anatomical decay and what controls this crucial process. Our findings can then be applied to the fossil record to allow a greater accuracy in correctly interpreting fossils and our understanding of evolutionary relationships through deep time.
Damage and repair in Wenlock reefs: evidence of predation on Silurian corals
Bethany Craik and Liz Harper
University of Cambridge, UK
Predation pressure is widely thought to have played a critical role in evolution. Most studies of predator–prey interactions described in the fossil record have focused on shelly molluscan or brachiopod prey. In particular, there are relatively few studies which have recognized predation evidence on fossil corals. Here we document damage and repair in corals from the Much Wenlock Limestone Formation (Silurian: Wenlock) of the English Midlands and Welsh Borderlands and test the hypothesis that they were caused by predators.
Counting the valid radiolarian genera in the Palaeozoic
Taniel Danelian1, Martial Caridroi1, Paula Noble2, Jonathan Aitchison3, Paulian Dumitrica4, Noritoshi Suzuki5, Jessie Cuvellier1, Joerg Maletz6, Kiyoko Kuwahara7, Qinglai Feng8 and Luis O’Dogherty9
1University of Lille, France
2University of Nevada, Reno, USA
3University of Queensland, Australia
4Université de Lausanne, Switzerland
5Tohoku University, Japan
6Freie Universität Berlin, Germany
7Ashiya University, Japan
8China University of Geosciences, Wuhan, China
9University of Cádiz, Spain
The first ever Palaeozoic radiolarian genus was described in 1890 from Ordovician cherts of Scotland. Not much happened for the following 60 years, until the milestone study of Deflandre, who, based on Carboniferous radiolarians from the Montagne Noir (France), established their evolutionary significance. In order to achieve taxonomic clarity and a sound appreciation of Palaeozoic radiolarian genus diversity, we have undertaken the preparation of an illustrated taxonomic catalogue for all 348 Palaeozoic genera described in the literature, including a re-illustration of the holotype of the type species of each genus. In our publication we will present a revised opinion of the status and family assignment of all Palaeozoic genera described so far, and will provide an up-to-date evaluation of their currently known age range. A taxonomic revision of the 348 generic names was conducted taking into account existing published opinion; this revision allowed us to identify 84 junior synonyms, six homonyms, one nomen nudum and 38 nomina dubia. Finally, 17 genera cannot be considered any longer as radiolarians, most of them being re-interpreted already in the literature as sponges. We intend for this atlas to serve as a useful taxonomic and biostratigraphic compendium in the palaeontological community.
Trends in trilobite moulting
*Harriet B. Drage
University of Oxford, UK
Arthropods periodically moult their exoskeletons for growth, development and repair. The methods by which they moult are consistent within clades of extant taxa, but trilobites show uniquely high levels of variation in this behaviour, both within and between species. Trilobites exhibit at least six distinct moulting behaviours, producing exoskeleton fragment configurations that are recognizable in the fossil record. Here I present results of a study exploring broad trends in trilobite ecdysial patterns through time and taxonomy. I examined collections of trilobite-moulted exoskeletons, housed in museums across the UK (London, Oxford, Birmingham) and Sweden (Uppsala), and combined this with information from the descriptive literature. These data consist of information on moulting behaviour, measures of morphology and complexity, and growth data. No clear evolutionary patterns in trilobite ecdysis have previously been identified, or interpreted in light of their admittedly poorly-constrained phylogeny. However, new data suggest the occurrence of different moulting behaviours, which vary between Orders and through time, and are associated with variation in body size. Trends in trilobite moulting behaviour relate to phylogeny, morphology and development, and have influenced the evolution and survivorship of the group. Future research will focus on moulting behaviour within well-sampled Orders and localities.
Spatial and temporal species richness of the fossil pollen genus Aquilapollenites using data from the John Williams Index of Palaeopalynology
*Emma Dunne1,2, Stephen Stukins2 and Andy Purvis2
1Imperial College London, UK
2Natural History Museum, London, UK
Occurrence databases are key to deciphering patterns of evolution, diversity, and biogeography through geological time. However, these databases are typically thought of as digital entities. The John Williams Index of Palaeopalynology (JWIP) is a cross-referenced index card system detailing global pre-Quaternary palynomorph occurrences and is believed to be the most comprehensive palynological database in the world. A proof of concept study, aimed at assessing the digitization potential of the card index, was undertaken on the fossil pollen genus Aquilapollenites. This genus is often affiliated with the modern angiosperm family containing the mistletoes, and belongs to an eminent group of pollen called the Triprojectates. Aquilapollenites is commonly associated with pollen assemblages of the Late Cretaceous and also the K/Pg extinction event. The data extracted from the JWIP revealed that Aquilapollenites suffered a 62% loss in global species richness at the K/Pg extinction event, a significant loss leading to the extinction of the genus soon after. The JWIP, despite being non-digital, allowed an exhaustive analysis of the temporal and spatial species richness of Aquilapollenites, and therefore presents a unique opportunity for studies of this kind. Given the nature of the data, the potential applications of the JWIP are infinite.
A new specimen of Othnielosaurus consors
*Armin Elsler1,2 and Jürgen Kriwet1
1University of Vienna, Austria
2University of Bristol, UK
Here we describe a new specimen of Othnielosaurus consors from the Upper Jurassic Morrison Formation. The specimen was found at the Howe Stephens Quarry (Wyoming, USA) and represents the most complete and largest single skeleton currently known for this taxon. The postcranial skeleton is virtually complete except for the forelimbs, which are only partially preserved. The specimen exhibits the most complete cranial material (including a relatively well-preserved lower jaw and a right maxilla) found in a single individual of the taxon. The preservation quality of the bones varies from relatively well preserved to heavily crushed. Slight differences between this skeleton and other specimens referred to Othnielosaurus consors are noted, but are explained by either individual or ontogenetic variation or the preservation quality of the specimen. Whether the size difference in comparison with other specimens is related to ontogeny or sexual dimorphism cannot be determined currently. A phylogenetic analysis recovers Othnielosaurus consors with the new character scorings as a member of Neornithischia and sister taxon to Cerapoda. This result differs from earlier assessments, which referred to the taxon as a ‘hypsilophodontid’ or basal ornithopod, and is in agreement with relatively recent phylogenetic studies.
Building a sedimentary geochemical database to understand the co-evolution of marine life and environments in a statistical framework
Úna C. Farrell1, David T. Johnston2, Noah J. Planavsky3 and Erik A. Sperling1
1Stanford University, USA
2Harvard University, USA
3Yale University, USA
After decades of intensive work, it is clear that the Neoproterozoic–Palaeozoic was an interval of considerable change in terms of marine redox conditions. Questions remain, however, about the magnitude and timing of palaeoenvironmental change, particularly in relation to significant events in the history of life and broad trends in diversity, ecology and morphology. Rigorous statistical analyses of long-term changes are hampered, in part, by insufficient data and limited data curation by the sedimentary geochemistry community. In keeping with the recent push towards improved data accessibility, aggregation, and standardization (e.g. Paleobiology Database, NSF IEDA, BGS OpenGeoscience, Macrostrat), here we discuss how we are bringing together new and existing datasets (in particular major and trace element concentrations, iron speciation, trace metal enrichments, and metal isotope values) in a relational database, based in part on the BGS and EarthChem data models. This allows for flexible querying across large datasets, efficient data import/export, quality control, and the establishment of good metadata standards. Ultimately, it will facilitate the analysis of redox conditions and shifts in biogeochemical cycling through time in a robust statistical framework, and enable comparison of changing palaeoenvironmental landscapes with new and existing compilations of animal body size, diversity and ecological guild occupation.
Recent benthic foraminiferal assemblages from mangrove swamps and channels of Abu Dhabi (United Arab Emirates)
Flavia Fiorini and Stephen W. Lokier
The Petroleum Institute, Abu Dhabi, UAE
Benthic foraminifera are an excellent tool to monitor marine coastal environments and to assist in the study of coastline change. Little is known about Recent foraminifera from mangrove swamps and channels of the Arabian Gulf. Detailed sampling collection in mangal environments of Eastern Abu Dhabi (UAE) was carried out to assess the distribution of benthic foraminifera in different sedimentary facies. Samples were collected in intertidal channels, mud flats and near the roots of Avicennia marina, and stained with Rose Bengal to identify the living foraminifera. The water salinity at the sampling sites was between 44 and 49 ppt. The samples collected in the higher energy settings (channels) were characterized by very low abundance of foraminiferal tests, no living forms were found in the coarser facies. The fine-grain sediments collected near mangrove roots presented a high abundance of living and dead foraminiferal tests. The assemblages in these samples show very low diversity and are almost entirely constituted of small-sized opportunistic species belonging to the genera Ammonia and Elphidium. The study of the distribution of Recent benthic foraminifera from mangrove environments of the Abu Dhabi region can provide reliable analogues for understanding and interpreting the depositional environment of ancient coastline sediments.
A new large-sized temnospondyl from the Permian of southern Brazil
Nubia Galvez1,2, Marco B. de Andrade1,2 and Rainer R. Schoch3
1Pontifícia Universidade Católica do Rio Grande do Sul, Brazil
2Museu de Ciências e Tecnologia da PUCRS, Brazil
3Staatliches Museum für Naturkunde, Stuttgart, Germany
Although the temnospondyl known diversity is substantial, the current knowledge of South American taxa is lacking. Remains of a large-sized temnospondyl from the Rio do Rasto Formation (Middle–Late Permian) of Southern Brazil represents a putative new taxon that may shed light on temnospondyl evolution and palaeobiogeography. The specimen MCP-4275PV is a hemimandible of ~50 cm in length, indicating that this specimen exceeded the majority of Brazilian temnospondyl taxa in size, only surpassed by the Late Permian Prionosuchus. Meaningful characters include a type I postglenoid area (PGA), hamate process and coronoids devoid of teeth, proportionally small but numerous dentary teeth. The short and posterodorsally-oriented retroarticular process parallels the morphology of certain Crocodylia, highlighting biomechanic similarities between these different tetrapod groups. Preliminary phylogenetic analysis (TNT, PAUP; 66 taxa, 217 characters) consistently places MCP-4275PV as the sister-group of Parotosuchus, a capitosaur genus currently known from Laurasian territories, South Africa and Antartica. If confirmed as a Parotosuchus, MCP-4275PV will expand the presence of the genus to South America. Furthermore, it will represent possibly the oldest capitosaur, a group almost entirely restricted to the Triassic. The future use of CT-scanning should provide access to new morphological data and the refinement of current results.
Resolving biology and taphonomy in Cambrian small shelly fossils
*Thomas W. Hearing1, Thomas H. P. Harvey1, Mark Williams1, Sarah Gabbott1, Philip Wilby2 and Melanie J. Leng3
1University of Leicester, UK
2British Geological Survey, UK
3NERC Isotope Geoscience Facility, UK
Small shelly fossils (SSFs) provide the earliest evidence of biomineralization in animals, first appearing in the latest Ediacaran (with Cloudina) before dramatically diversifying during the Cambrian. They represent stem group members of at least six metazoan phyla, in addition to various problematic taxa. SSFs occur as phosphatic, calcareous and siliceous microfossils, but are often preserved by secondary mineralisation. This hinders resolution of their original ultrastructure and composition which in turn obscures the phylogenetic relationships of these early animals. Richly fossiliferous horizons in the Lower Comley Limestone (Lower Cambrian, Shropshire, UK) were targeted to test biomineralogical and phylogenetic hypotheses of key SSF taxa. This unit is known for its secondarily-phosphatised preservation of micro-arthropods (phosphatocopids), but it also yields a diverse SSF assemblage. Scanning electron and optical microscopic examination revealed well-preserved biogenic ultrastructures in many of the phosphatic SSFs, including differential laminae of linguliformean brachiopod shell secondary layers and growth laminae in hyolithelminths, lapworthellids and the spinous genus Rhombocorniculum. These microfossils are unusually free from secondary mineralisation and can shed light on the biomineralogy and phylogenetic relationships of key early metazoan taxa. The high-fidelity preservation of these SSFs also makes them suitable candidate sources of isotopic constraints on Cambrian marine environments.
Diversity and morphological disparity of the Rhynchocephalia
*Jorge A. Herrera-Flores and Michael J. Benton
University of Bristol, UK
Rhynchocephalia is an order of reptiles that originated in the Triassic. Today this group is only represented by a single living species, Sphenodon punctatus. For many years, it was believed that the Rhynchocephalia did not change through time, because some of the fossil species and the extant Sphenodon showed a very similar morphological structure. This argument lies behind the common description of the extant Sphenodon as a living fossil. However, during the last 20 years many fossil species have been described, which have provided information about their morphological diversity in the past, and suggested that there was considerably more variation in form than previously believed. In order to explore the macroevolution of Rhynchocephalia, we performed a diversity and disparity analysis of this group. Also, we explored morphospace occupation through the Mesozoic by using landmarks of the lower jaw. This shows that the modern Sphenodon lies close to the centroid of the morphospace plot. Triassic and Jurassic rhynchocephalians show the greatest occupation of morphospace, and disparity has, overall, declined substantially through the Mesozoic and Cenozoic. When divided into feeding morphospaces, there has been a distinct movement in morphospace through time.
Correlation of avian wing loading and aspect ratio with track: application for estimation of extinct avian body
Kobe University, Japan
Avian wings connected to locomotion of flying have possibly evolved adapting to habitat types. Modern avian wing parameters were analysed to examine if wings are grouped constrained by habitats, as tracks are morphologically divided into three groups corresponding to habitat types. Multiple regression analyses of the wing and track data reveal that the avian wing loading and aspect ratio are closely related to the track shape parameter (the primary principal component of the relative warp analysis), expressed by a simple equation that enables the quantitative estimation of the wing parameters from track shapes. These results confirm that avian wings are also divided into three groups corresponding to habitat types. Thus, habitats are closely related to avian wings as well as tracks, and seem to constrain both flight and walking, as a result of adaptation. Using the correspondence relation between wing parameters and track area found in this study, body weights were estimated for extinct avian taxa from the Cretaceous to Cenozoic periods. The estimated weights support the hypothesis that the early Cenozoic avian was larger in size than Cretaceous ones.
The cranial biomechanics of Effigia okeeffeae and its convergence with Ornithomimosauridae
*Andrew S. Jones1, David J. Button2, Andrew R. Cuff3 and Emily J. Rayfield2
1University of Birmingham, UK
2University of Bristol, UK
3University College London, UK
Convergent food processing morphology may indicate functional or ecological analogy; however, form and function frequently decouple, meaning explicit testing is required to investigate such hypotheses. The edentulous cranium of Effigia okeeffeae (Archosauria: Pseudosuchia) is here compared functionally to those of the ornithomimosaurids Struthiomimus altus, Ornithomimus edmontonicus and Garudimimus brevipes (Archosauria: Dinosauria), to which it has previously been compared qualitatively. Digital retrodeformation of the holotype skull (AMNH FR 30587) of Effigia was performed using CT data, before conversion into a finite element (FE) mesh. Adductor and temporal musculature was digitally reconstructed using attachment scars, osteological constraints and extant phylogenetic bracketing. Bite force, estimated from cross-sectional muscle areas, was applied to the mesh simulating rostral, mid and posterior biting. Accounting for size, we estimate Effigia to have possessed a bite force comparable to the ornithomimosaurids, however results of FE analyses indicate Effigia, unlike ornithomimosaurids, was poorly adapted to rostral biting. This may be partially due to the comparatively large nares of Effigia, placed posterior to the rostral bite point (rather than dorsal to the bite point in ornithomimosaurids) channelling compressive rostral stresses through the thin narial septum. While similarly edentulous, minor cranial differences make Effigia and ornithomimosaurids unlikely as direct ecological analogues.
Disturbance and diversity in the Ediacaran: integrating sedimentology and palaeontology through multivariate statistical analysis
*Charlotte G. Kenchington1,2
1University of Cambridge, UK
2British Geological Survey, UK
Rangeomorphs dominate the Ediacaran successions of Newfoundland (Canada) and Charnwood Forest (UK), and are characterized by their complex, pseudo-fractal branching architecture. Understanding of their biology is hindered by the lack of known extant counterparts, and even fundamental aspects such as taxonomy remain under revision. Despite the uncertainty surrounding these organisms, there is the potential to resolve many aspects of their ecology. Individual bedding surfaces host communities which are remarkably different in terms of their community composition and diversity. In modern ecosystems, such aspects of the community are influenced by several biological and abiological factors; many of these (predation, burrowing) would have been limited or absent in the Ediacaran, whereas physical constraints such as disturbance would still have been in effect. By correlating detailed petrographic analysis with morphological analysis over 25 fossiliferous sites (using complex multivariate statistical techniques), several palaeobiological features including fine-scale tiering, community structure and ecological succession can be elucidated. Importantly, communities with the highest diversity were those with demonstrably intermediate levels of environmental disturbance, a feature typical of modern ecosystems. This work highlights the influence of subtle, transient environmental parameters on the composition of these ancient communities, and reveals the temporal persistence of fundamental ecological principles.
Phase changes in the microfossil assemblages during the early Toarcian (Lower Jurassic)
*Alice E. Kennedy and Angela Coe
The Open University, UK
The early Toarcian oceanic anoxic event (TOAE) was a period of extreme environmental change. The TOAE succession exposed in Yorkshire, UK, shows significant perturbations to geochemical proxies and macrofossil assemblages, indicating a rise in global temperature, increased extent of deoxygenation and marine invertebrate extinctions. Foraminifera and palynomorphs from samples taken every 10 cm, geochemical proxies (Kemp et al. 2011; Pearce et al. 2008) and macrofossil data (Caswell and Coe 2013), together with an improved method of foraminiferal extraction (Kennedy and Coe 2014), demonstrate a three-phase change during the TOAE. Phase 1 records a stepped deterioration in open marine assemblages and increase in terrestrial abundance, interpreted as evidence of enhanced continental runoff. One Milankovitch cycle below the onset of the TOAE sensu stricto foraminifera disappear. Phase 2, which represents the start of the TOAE sensu stricto, is defined by a shift from an open marine to restricted, sphaeromorph assemblage. Phase 3 is characterized by a substantial sphaeromorph bloom contemporaneous with a significant change in terrestrial vegetation.
Digital restoration of the cranial skeleton of Morganucodon oehleri
Stephan Lautenschlager1, Pamela Gill1, Michael Fagan2 and Emily J. Rayfield1
1University of Bristol, UK
2University of Hull, UK
Morganucodon oehleri is a basal mammaliaform found in Upper Triassic and Lower Jurassic deposits of Europe and China. Although the species is represented by numerous fossils, these are mostly restricted to isolated teeth and fragmentary elements. Solely a handful of articulated, albeit distorted and incomplete, cranial skeletons form the exception. While the morphology of individual elements, in particular of isolated teeth, has been studied in great detail in the past, reconstructions of the cranial skeleton have been limited to two-dimensional interpretive drawings. Based on high-resolution CT scans of a nearly complete and articulated skull of M. oehleri (FMNH CUP 2320), a digital restoration of the cranial skeleton was performed using a suite of virtual restoration techniques. The newly restored skull shows several distinct differences to previous reconstructions. The supraoccipital region is laterally convex and characterized by a distinct sagittal crest, suggesting the presence of a well-developed temporalis musculature. The coronoid process of the lower jaw is positioned posterior to the level of the alisphenoid and extends dorsally, almost to the level of the parietal, thus reducing the length of the temporalis muscle. In this, the hypothesized morphology provides new information on the sequence of character acquisition and morphological evolution at the cynodont–mammaliaform transition.
Stylophoran echinoderms of the Afon Gam Konservat-Lagerstätte (Lower Ordovician, Wales)
Bertrand Lefebvre1, Joseph P. Botting2,3 and Lucy Muir3
1Université Lyon 1, France
2Nanjing Institute of Geology and Palaeontology, China
3Amgueddfa Cymru – National Museum Wales, UK
In contrast to the Cambrian Explosion, our knowledge of the Great Ordovician Biodiversification Event (GOBE) relies primarily on shelly fossils. The Afon Gam Lagerstätte, from the early late Tremadocian (Lower Ordovician) of Bala area, North Wales, partly fills this gap. The Afon Gam Biota consists almost exclusively of Cambrian‑like taxa. Contrary to the situation in the contemporaneous Fezouata Biota (Morocco), it has not yielded any representatives of groups typical of the GOBE (e.g., asterozoans, crinoids, eurypterids, graptolites, ostracods, xiphosurans). The Afon Gam Biota is dominated by diverse sponges, algae and various kinds of worms, associated with inarticulate brachiopods, trilobites and occasional other arthropods (e.g., bivalved forms, mollisoniid-like taxa), cnidarians, hyolithids, tergomyan molluscs and echinoderms. The composition of the Afon Gam echinoderm assemblage (eocrinoids, glyptocystitid rhombiferans and stylophorans) is strikingly similar to the low-diversity Furongian echinoderm faunas recorded worldwide (e.g., Australia, China, France, Korea, USA). Stylophorans are rare and are represented by three taxa: 1) a basal chauvelicystid cornute (probably intermediate between Chauvelicystis and Prochauvelicystis); 2) a basal amygdalothecid cornute; and 3) a kirkocystid mitrate (Anatifopsis trapeziiformis). This stylophoran assemblage suggests relatively strong affinities with both Furongian and Tremadocian/early Floian faunas.
Remarkable lophotrochozoans from the Weeks Formation Konservat-Lagerstätte (Cambrian Series 3; Utah)
Rudy Lerosey-Aubril1, *Javier Ortega-Hernández2, Robert Gaines3, Thomas Hegna4 and Peter Van Roy5
1University of New England, Australia
2University of Cambridge, UK
3Pomona College, Claremont, USA
4Western Illinois University, USA
5Ghent University, Belgium
The Guzhangian Weeks Formation is the least well-known of the three Cambrian Konservat-Lagerstätten of the House Range (Utah). Yet, new collection efforts reveal that its faunal diversity (>80 species, including 30 ‘soft’-bodied) rivals that of both the Wheeler and Marjum Formations. Ecdysozoans, especially arthropods (57 species), are by far the most diverse components. By contrast, lophotrochozoans are only represented by a single hyolith species and two brachiopod species, despite the great abundance of the latter. Three new possible representatives of this group were recently discovered. One taxon has an elongate body with pairs of short, setae-bearing lateral lobes. It strongly resembles extant dorvilleid polychaetes and is therefore regarded as the first annelid from the Weeks Formation. Another taxon comprises a large (6 cm), three-dimensionally preserved, asymmetrical shell with growth lines and a straight hinge. These features suggest that the fossil represents a disarticulated valve of a bivalved mollusc. The last taxon has an elongate body (>5 cm) composed of a thick peduncle and a capsule. The capsule was originally semi-rigid and has a second opening laterally. Both parts are preserved in apatite, possibly reflecting the original mineralogy of the capsule. Lophophorate affinities of this taxon are discussed.
Empirical and simulation approaches to detecting barriers to dispersal in extinct terrestrial organisms: testing the effects of Pangaean breakup and avian flight on Mesozoic dinosaurs
Graeme T. Lloyd1 and Laura C. Soul2
1Macquarie University, Australia
2Smithsonian Institution, USA
A terrestrial organism’s ability to disperse can be restricted by major barriers such as oceans, or enhanced by an enabling trait such as powered flight. However, most currently adopted palaeobiogeographical methods require a priori designation of discrete areas, thus making prior assumptions regarding dispersal barriers. Here, by contrast, we use the raw continuous data of palaeocoordinates of latitude and longitude as input, and combine this with phylogenetic data as a means of inferring the existence or breakdown of barriers to dispersal without defining discrete areas. As a case study, we use Mesozoic dinosaurs, a group that spans the breakup of Pangaea and the origin of a major dispersal-enhancing trait (powered flight). Palaeocoordinate data were sourced from the Paleobiology Database and phylogenetic data come from a probabilistically time-scaled 1000-taxon supertree. Initial results suggest that there is little or no evidence for barriers to dispersal when Pangaea was intact, but this changes in the Middle Jurassic. Similarly, early birds do not differ from non-avian dinosaurs until the Late Cretaceous where apparent intercontinental dispersal is observed. A simulation approach under two simple models (an intact and a rifting-apart Pangaea) broadly support our empirical interpretations. We conclude by suggesting ways in which our simulation model could be extended, for example to investigate marine organisms.
Community ecology of Cambrian deep-marine scratch circles
Breandán Anraoi MacGabhann1,2,3, Emily G. Mitchell4 and John Murray3
1Edge Hill University, UK
2University of Edinburgh, UK
3National University of Ireland, Galway, Ireland
4University of Cambridge, UK
The early Cambrian witnessed not only the rise of biomineralized organisms, but also a fundamental change in marine ecology, including the evolution of widespread bioturbation and a shift from Neoproterozoic-style microbial matground seafloors to more typical Phanerozoic-style bioturbated mixgrounds. However, this latter shift was delayed in deep-water settings, and the ecology of deep-marine Cambrian communities is not well-known. We investigated the palaeoecology of the deep-marine Middle Cambrian Booley Bay Formation (southeast Ireland), which contains bedding sole surfaces covered by numerous millimetre-scale scratch circles (arcuate scratches made in the substrate by the current-forced rotation of tethered epibenthic organisms) with distributional concentrations reaching 30,000 individuals per square metre. Surfaces were photographed at high-resolution, with position and morphological data (e.g. size, number of rings, presence of a central tubercle, orientation) recorded using image processing software and exported into R for in-depth spatial analysis. Spatial distribution is described by pair correlation functions (PCF) calculated from the position data, with spatial models fitted to the PCFs to distinguish environmental from biological causes, mark correlation functions and PCF models of the circle sizes used to investigate growth and reproduction strategies, and random labelling analysis of morphological features used to consider scratch circle taphonomy.
The role of shifting salinity in soft tissue preservation in concretions
*Victoria E. McCoy
University of Leicester, UK
Shifting salinity is characteristic of the coastal deltaic deposits that comprise the majority of exceptional fossil sites, such as the Mazon Creek concretion site, from the Carboniferous to Triassic. Shifting salinities are hypothesized to influence exceptional preservation by inhibiting decay. This project investigated: 1) the effect of shifting salinities on decay by measuring decay (using weight change and infrared gas analysis) in experiments that simulate environments with and without salinity fluxes; and 2) the role of shifting salinities in soft tissue preservation at the Mazon Creek fossil site by strontium isotope analysis of concretions with and without fossils. The experiments using weight change as a measure of decay suggest that increasing salinity inhibits decay. The experiments using infrared gas analysis as a measure of decay suggest that a flux of meteoric water into seawater inhibits decay, but a flux of seawater into freshwater promotes decay. The strontium isotope analysis of Mazon Creek concretions does not suggest that the concretions containing exceptional fossils developed during times of salinity fluxes. Therefore, these experiments and analyses do not support the idea that shifting salinities promote exceptional fossilization.
A revision of tetrapod tracks from the Late Carboniferous of Hamstead, West Midlands
*Luke Meade, Andrew Jones and Richard J. Butler
University of Birmingham, UK
The Late Carboniferous to Early Permian was an interval of major global environmental change, with increasing aridity leading to the collapse of the previously widespread humid, tropical rainforests (the ‘Coal Forests’). This environmental transition is hypothesized to have driven major changes in terrestrial tetrapod communities, with the amphibians that dominated Carboniferous ecosystems being replaced by early amniotes (‘reptiles’). A set of red sandstone slabs from Hamstead, West Midlands, UK, preserve a collection of tetrapod trackways and individual tracks from the Late Carboniferous. This material has received limited previous study, despite being one of the few British sites to preserve Carboniferous tetrapod footprints. We restudied, documented and revised the taxonomy of this material using 3D photogrammetric models and rendered images highlighting coloured contour intervals and areas of changing gradient. The assemblage is dominated by large tracks assigned to Limnopus isp. (made by early amphibians) with a series of smaller yet similar tracks being assigned to Batrachichnus salamandroides (also made by early amphibians). Dromopus lacertoides (made by the lizard-like araeoscelids) and Dimetropus leisnerianus (made by early synapsids) were also identified. This ichnofauna contrasts with the slightly older and better-studied assemblage from Alveley (Shropshire, UK), which is dominated by small amphibians and reptilomorphs.
A review of the Danian vertebrate fauna of southern Scandinavia
Jesper Milàn1, Jan S. Adolfssen1, Matt Friedmann2 and Niels Bonde3
1Geomuseum Faxe, Denmark
2University of Oxford, UK
3Natural History Museum of Denmark, Denmark
Vertebrate remains are widely distributed, but uncommon in the early to middle Danian limestone deposits of eastern Denmark and southern Sweden, and are mostly represented by bony fishes and Chondrichthyans. The lowermost Danian Fishclay at Stevns Klint can include substantial quantities of shark teeth and fragments of bony fishes. Although articulated specimens of osteichthyans are known from the Fiskeler and the Limhamn quarry, there are no known body fossils of elasmobranchs from the Danian of Denmark or Sweden. Reptile and bird remains are very rare. The gavialoid crocodylian Thoracosaurus is represented by a complete skull and associated postcranial material and an additional jaw fragment from Limhamn quarry, Sweden. Further remains of a crocodilian skull, a cervical vertebra, a limb bone and a few teeth have been found in Faxe Quarry, and a single possibly alligatorid tooth are known from the basal conglomerate of the Lellinge Greensand Formation of Copenhagen. Fragmentary turtle material has been found in Faxe and Limhamn quarries and in the late Danian København Limestone of Copenhagen. Bird remains are exclusively known from Limhamn quarry. Together this gives a picture of a diverse vertebrate fauna from the Danian of southern Scandinavia.
The Cretaceous-Paleogene boundary section at Stevns Klint, Denmark – UNESCO World Heritage and the future of palaeontological research
Jesper Milàn, Ane Elise Schrøder and Tove Damholt
Østsjællands Museum, Højerup Bygade 38, DK-4660 Store Heddinge, Denmark
Stevns Klint in the eastern Denmark arguably comprises the best exposed Cretaceous-Paleogene boundary section in the world, and in 2014 the site was declared a UNESCO World Heritage Site.
The exceptional complete marine fossil record present at Stevns Klint makes the site among the best localities worldwide for studying marine biotic turnover across the K-Pg boundary, and the discovery of the iridium anomaly in the boundary clay layer in 1980 made the site a key locality in the scientific debate about an impact vs. volcanism related cause for the End Cretaceous extinction.
The management of Stevns Klint as a World Heritage Site is developed in order to secure protection of the site in a manner that encompasses the opportunity for sampling for scientific purposes and encourages continued research activity. According to the agreed guidelines sampling in the cliff face for scientific purposes may be permitted by the local geological museum, Østsjællands Museum. The museum invites all researchers to contact the museum not only to obtain permits but also to participate in the effort to communicate the scientific importance of the site to the general public.
Rock fossils on Tour – an innovative concept in palaeontological outreach.
Jesper Milàn1, Esben Horn2 and Rune Fjord3
1Geomuseum Faxe/Østsjællands Museum, Højerup Bygade 38, DK-4660 Store Heddinge, Denmark
210Tons APS, Ved Slusen 34, DK-2300 København S., Denmark
3Rune Fjord Studio, Ved Slusen 34, DK-2300 København S., Denmark
Zoological nomenclature, the science of naming extant and extinct organisms can seem like a dull field with little public appeal. However, a new travelling exhibition “Rock Fossils on Tour”, dealing with just that theme, has managed to attract a wide audience and reach far out of the normal palaeontological circles, and straight into the heart of heavy metal fans!.
The exhibition is based on fossils that are named after rock, punk, and heavy metal stars, and features exclusive lifelike reconstructions of the animals, portrays of the rockstars their names honors, and amusing anecdotes from the scientists behind the names. Many of the items have been signed by the rock stars themselves. The exhibition has gained extensive attention in the music press and music news groups worldwide, and has generally been very well received by both music and fossil fans in the four museums it has visited so far.
This is the story of how the exhibition came to be, its rise to success, and the plans for its future expansion.
Early burst in the colonization of continental ecospace and the evolution of behaviour
Nicholas J. Minter1, Luis A. Buatois2, M. Gabriela Mangano2, Neil S. Davies3, Martin R. Gibling4, Robert B. MacNaughton5 and Conrad Labandeira6
1University of Portsmouth, UK
2University of Saskatchewan, Canada
3University of Cambridge, UK
4Dalhousie University, Canada
5Geological Survey of Canada, Canada
6Smithsonian Institution, USA
The colonization of land was a major evolutionary transition. Ichnological evidence suggests that this process may have begun at the end of the Ediacaran, with incursions into very shallow, marginal-marine settings. Animals made their first unequivocal amphibious terrestrial forays during the Cambrian and had managed to establish themselves in truly alluvial environments by the Late Ordovician. The remainder of the Palaeozoic is characterized by an explosion of diversity and a progressive expansion from coastal settings inland into rivers, floodplains, deserts and lakes; as well as increasing colonization of infaunal ecospace and the creation of new niches. A framework is presented for analysing ecospace occupation and ecosystem engineering through the use of trace fossil data. The colonization of each new continental environment may be viewed as a series of repeated experiments in ecospace filling and niche creation. A pattern emerges in which colonization of a new environment is followed by rapid filling of ecospace, after which animals establish new behavioural programmes represented initially by the appearance of original trace fossil architectural designs, and subsequently by a proliferation of ichnogenera representing variation upon these established themes. This pattern is consistent with the early burst model of diversification.
Impact of spatial heterogeneities on Ediacaran communities from Mistaken Point, Newfoundland
Emily G. Mitchell
University of Cambridge, UK
Bedding-plane assemblages of Ediacaran fossils at Mistaken Point, Newfoundland, Canada (~565 Ma), are among the oldest known examples of macroscopic communities. The constituent organisms have few similarities with living forms, making their relationship with their environment difficult to assess. Their preservation in large in situ bedding plane populations allows original spatial distributions to be analysed, shedding light on the interactions between taxa and their environment. The most fossiliferous ‘E’ surface was mapped using differentiated GPS to millimetre accuracy. Spatial correlations between taxa were identified using Bayesian network inference, then described and analysed using pair correlation functions. Of the eight inter-taxa relationships found, five were the result of impact by four different environmental heterogeneities, and three the result of interactions between living and dead organisms. For two interactions, the presence of small-scale environmental aggregations with large-scale segregations shows that these taxa were competing over environmental resources. The spatial distributions of these competitive interactions were found to mirror extant communities where taxa reduced inter-specific competition by niche differentiation instead of trading off competitive advantages over colonization ability. Thus, while over ten times smaller than individual taxa interactions, these environmental impacts were still sufficient to drive competition and likely niche differentiation.
An enigmatic large discoidal fossil from the Pennsylvanian of County Clare, Ireland
John Murray1, Breandán Anraoi MacGabhann1,2,3, Eamon Doyle4 and David A. T. Harper5
1National University of Ireland, Galway, Ireland
2Edge Hill University, UK
3University of Edinburgh, UK
4Burren and Cliffs of Moher Geopark, County Clare, Ireland
5Durham University, UK
A rare and unusual, large solitary discoidal fossil, c. 130–135 mm in diameter, has been discovered on a paving slab quarried from the cyclothemic Central Clare Group (Kinderscoutian, Pennsylvanian, Carboniferous) of western Ireland. The fossil impression consists of a smooth raised inner discoidal area, c. 80 mm across, surrounded by a slightly lower-relief outer ring with eight prominent equidistant ovoid raised nodes towards the outermost margin. The specimen is surrounded by a shallow groove. Classification of this enigmatic fossil remains unclear, although the octoradially symmetrical body plan suggests possible cnidarian affinities. The specimen is palaeoecologically interesting: it occurs within the world-renowned Liscannor Flagstone, which consists of thinly bedded, fine-grained sandstones which are extensively covered by prominent, sinuous to meandering Psammichnites [= Olivellites] horizontal feeding trails (c. 10–20 mm in width). This sedimentary facies is generally interpreted as representing mouth bar sedimentation in a delta front succession. The organism responsible for the discoidal impression was clearly too large to have made the Psammichnites trails and it occurs on a portion of the slab where these burrows are scarce. Either the Psammichnites trace-makers deliberately avoided this larger solitary organism, or this is merely chance preservation, with intensive bioturbation routinely obliterating other impressions of similar discoidal organisms.
Testing hypotheses of niche partitioning in isolated fossil mammal teeth based on quantitative 3D dental microwear texture analysis
*Christopher Nedza1, Mark Purnell1 and Leszek Rychlik2
1University of Leicester, UK
2Adam Mickiewicz University in Poznań, Poland
The earliest, most basal mammals are widely considered to be generalized insectivores. Accumulating evidence indicates that slightly later mammals have greater ecomorphological diversity than previously suspected, but testing for dietary differences between the earliest taxa, known primarily from teeth alone, is problematic. This study tests the hypothesis that tooth microwear varies between extant insectivores which are known to exhibit partitioning of the dietary niche, and that analysis of tooth microwear textures can be used to detect subtle dietary differences between fossil taxa. Our analysis extends recent work on insectivorous bats by incorporating data from four species of sympatric ground-feeding and semi-aquatic shrews, and other mammal insectivores. The results elucidate the pattern of tooth textural differences among small mammal insectivores and provide new insights into differences between aerial and ground-based feeding. Application to fossil mammals provides further support for the hypothesis that 3D textural microwear analysis can be used for subtle, within-guild dietary discrimination in taxa known only from teeth.
Far offshore depositional conditions and animal behaviour as indicated by trace fossils in the Eocene Lillebælt Clay Formation, Denmark
Jan K. Nielsen1, Jesper Milàn2 and Daniel Mesfun3
1VNG Norge, Norway
2Geomuseum Faxe, Denmark
3GXU Gladsaxe, Denmark
The major Ypresian transgression is evident in earliest Eocene strata of northwestern Europe. The Eocene strata of Denmark comprise mostly regionally distributed deposits of the Røsnæs Clay, Lillebælt Clay and Søvind Marl formations. The Lillebælt Clay Formation was formed during late Ypresian to early Lutetian, laterally equivalent to an interval of the Horda Formation in the North Sea Central Trough. It consists mostly of greyish to greenish, non-calcareous clay. In western Zealand, the Lillebælt Clay Formation contains a diverse trace-fossil assemblage, formally described for the first time. The preservation of the trace fossils is predominantly related to early diagenetic enhancement. The trace-fossil assemblage is characterized by a combination of dwelling and feeding burrows representative of the distal Cruziana ichnofacies and comprises Atollites zitteli?, Bichordites isp., Chondrites isp., Dreginozoum beckumensis, Ophiomorpha nodosa, Phymatoderma melvillensis, ?Rhizocorallium isp., Spongeliomorpha isp., and unnamed clusters of small burrows. The bioturbation took place in hemipelagic clay of a shelf setting far from the palaeocoast. At least periodically, the oxygen levels were high enough to enable tracemakers to colonize the sea bottom.
Exceptionally preserved arthropodan microfossils from the Winneshiek Lagerstätte
Hendrik Nowak1, Thomas H. P. Harvey2, Huaibao Liu3, Robert M. McKay3 and Thomas Servais1
1CNRS-University of Lille, France
2University of Leicester, UK
3Iowa Geological Survey, USA
The Middle Ordovician Winneshiek Shale (Darriwilian; Winneshiek County, Iowa, USA), hosts a Konservat-Lagerstätte that has yielded a diverse fauna including eurypterids, phyllocarids, ostracods, bromalites, linguloids, giant conodonts, mollusks, acritarchs and algal cells, and possible jawless fish. The shale is rich in organic content, including fragmentary cuticular remains. Palynological acid treatment enables the extraction of these small carbonaceous fossils (SCFs) from the matrix, allowing a more detailed view of their morphology. In addition to abundant eurypterid material, this method has yielded exceptionally well-preserved crustacean-type setae and a population of distinctive microfossils that we tentatively identify as the mandibles of a small-bodied crustacean. The Winneshiek mandibles share some important features with those of branchiopod crustaceans, including the apparent lack of a mandibular palp, but they are unusual in having a curved gnathal edge with no division into incisor and molar processes. The abundance of the mandibles points to a previously cryptic organism of importance in the Winneshiek biota or a nearby ecosystem. By comparison to previously described crustacean SCFs from the Cambrian of Canada, the Winneshiek fossils both extend the range of this taphonomic window, and imply an ecological expansion of small-bodied crustaceans into restricted, marginal marine environments by the Middle Ordovician.
Testing functional hypotheses in cinctans (middle Cambrian Echinodermata) using computational fluid dynamics
James O’Shea1, Stephan Lautenschlager1, Samuel Zamora2 and Imran A. Rahman1
1University of Bristol, UK
2Instituto Geológico y Minero de España, Spain
Cinctans are a clade of non-radial echinoderms restricted to the middle Cambrian of Gondwana (including Avalonia) and Siberia. They comprise a flattened body (theca) with an anterior mouth and a stiff posterior appendage (stele). The theca shows considerable variation in shape among species, ranging from strongly asymmetrical to almost bilaterally symmetrical; the functional significance of this morphological variation is unclear. To explore this, three-dimensional models of six cinctan taxa were constructed using the open-source 3D creation suite Blender. These taxa were chosen to represent a range of morphologies from across cinctan phylogeny. The models were then subjected to computational fluid dynamics simulations using the modelling software COMSOL. The results show that drag and lift were elevated in taxa with a more strongly asymmetrical theca, suggesting that these species were more prone to dislodgement in life. This study will shed light on the ecology of this unique clade, contributing to our understanding of the selection pressures acting on echinoderms during the Cambrian.
Plant macrofossils from the Homerian (Wenlock, Silurian) of Stonehaven, Scotland
*Javier Ortega-Hernández1, Ben Slater1 and Russell Garwood2
1University of Cambridge, UK
2University of Manchester, UK
The Cowie Harbour fish bed is exposed at an offshore locality north of Stonehaven, Aberdeenshire, UK, and preserves a diverse fossil biota including jawless fish and euarthropods. This locality is best known for producing the earliest evidence of animals inhabiting an aerial terrestrial environment, in the form of a fragmentary millipede with preserved orifices for air-breathing. Although the age of the Cowie fish bed has been regarded as Homerian (late Wenlock) based on the preserved sporomorph diversity, the section has not yielded plant macrofossils to date. A recent collection effort at this locality produced an assemblage of well-preserved plant macrofossils. In addition to simple forms with dichotomous branching similar to the early land plant Cooksonia, new discoveries include a large (> 5 cm in length) lycophyte-like taxon characterized by helically arranged scaly leaflets and an absence of ramifications. Aspects of the morphology of the ‘Cowie lycophyte’ resemble stratigraphically younger vascular plants, such as the Gorstian (Ludlow, Silurian) Baragwanathia from Australia, and the Pragian (Lower Devonian) Asteroxylon from the Rhynie Chert in Scotland. Pending further study, these findings tentatively push back the earliest occurrence of complex vascular plants in the fossil record, and suggest a cryptic diversification of this group during the early Silurian.
Semuridia dorsetensis (Bivalvia, Pergamidiidae): new chronostratigraphy, palaeobiogeography and palaeoautoecology data from the Pliensbachian (Lower Jurassic) of Iberia
Universidad Complutense de Madrid, Spain
The pterioid bivalve Semuridia dorsetensis was first described by Cox in 1926 as a new inoceramid species and later assigned to Melville´s genus Semuridia in 1969. There are some similitudes with inoceramids due to the external mytiliform outline. Nevertheless, the hinge details and a small anterior auricle distinguish them. Only a few individuals are known: the holotype and three paratype specimens held at the Natural History Museum, London. They were also referred as “unusual bivalves”. A large sample of individuals was collected from Basque-Cantabrian and Asturias Basins sections (northern Iberia). The newly-collected material is chronostratigraphically well-constrained as Jamesoni Chronozone (Brevispina Subchronozone) to Ibex Chronozone intervals in those basins. The type material comes from Obtusum Chronozone (Obtusum Subchronozone) on the Dorset coast, UK (Wessex basin). It might be interpreted that the populations of southern England were later represented (~4.5 Ma) in the northern Iberian basins. Those migrations seem to be related to sedimentary facies changes as all occurrences relate them with organic-rich mudstones. The inferred benthic, epifaunal suspensivorous autoecology of these species does not exclude the facultative pseudoplanktonic habit due to the presence of a byssal notch. Alternatively they could be regarded as capable of surviving in low-oxygenated bottom waters.
Confirming the validity of late Ediacaran bioturbation via study of 3D morphology, taphonomy, and petrology
Christos Psarras1, Alexander G. Liu1, Dmitriy V. Grazhdankin2, Vladimir I. Rogov2 and Philip C. J. Donoghue1
1University of Bristol, UK
2IPGG Novosibirsk, Russia
Molecular clocks predict the origin of the clade Metazoa tens of millions of years prior to the Cambrian Explosion. However, existing body fossil evidence for their presence in the preceding Neoproterozoic Era is equivocal. Trace fossils provide an alternative record of metazoan morphological and behavioural evolution. Material from the late Ediacaran Khatyspyt Formation (~553Ma) of Arctic Siberia has been suggested to record evidence of abundant bioturbation, but this interpretation has been disputed. Here we combine X-ray tomography, SEM, and petrological analyses to investigate the three-dimensional morphology and taphonomy of this important material. The material is demonstrated to comprise of randomly-oriented series of bowl-shaped structures within a sedimentary ‘halo’, while taphonomic studies indicate that the structures have diffuse, silicic mineralogical boundaries. These results refute the suggestion that the Siberian material preserves body fossils of tubular organisms similar to Cloudina, and instead confirm an ichnological origin. We propose meniscate backfill as a mechanism to explain the morphology and mineralogy of these structures, implying that triploblastic Eumetazoan burrowers were present more than ten million years before the Cambrian Explosion.
Macroevolutionary trends through the Lower Jurassic in Bulgaria
*Autumn C. Pugh1, Crispin T. S. Little1, Ivan P. Savov1, Paul B. Wignall1, Robert J. Newton1, Lubomir Metodiev2 and James B. Riding3
1University of Leeds, UK
2Bulgarian Academy of Sciences, Bulgaria
3British Geological Survey, UK
The Lower Jurassic (201–174 Ma) was a time of global environmental change. At the beginning of the Lower Jurassic, ecosystems were recovering from the late Triassic mass extinction event and subsequently, in the early Toarcian, there was a benthic crisis. Despite the importance of tracking the long-term faunal trends of ecosystem recovery, stability and collapse through this critical 27 myr time period, relatively few studies have documented in detail the ecological changes between the two extinction events. We will present a quantitative palaeoecological analysis of invertebrate macrofauna from the upper Hettangian–upper Toarcian sedimentary successions in northwest Bulgaria. Bulgaria provides a unique opportunity to investigate effects of changing sea-level and resulting facies variation on ecosystem stability from the eastern margin of the Tethyan epicontinental platform. This location has a more direct link with the open ocean and is therefore more likely to be representative of worldwide biotic changes, than the better studied Lower Jurassic sections in northwest Europe. Differences include a lack of black shales and variability in faunal turnover leading up to and during the early Toarcian, showing this extinction event and associated environmental changes differed between Bulgaria and northwest Europe.
A new fauna of early Carboniferous Chondrichthyans from the Scottish Borders
*Kelly R. Richards1, Janet E. Sherwin2, Timothy R. Smithson1, Rebecca F. Bennion1, Sarah J. Davies2, John A. Marshall3 and Jennifer A. Clack1
1University of Cambridge, UK
2University of Leicester, UK
3University of Southampton, UK
Chondrichthyan teeth from a new locality in the Scottish Borders expand evidence of early Carboniferous chondrichthyans in the UK. The interbedded dolostones and siltstones of the Ballagan Formation exposed along Whitrope Burn are interpreted as a restricted lagoonal environment with fluvial input. This site is dated to the Late Tournaisian – Early Viséan by palynological evidence. The diverse dental fauna documented here is dominated by large crushing holocephalan toothplates, with very few, small non-crushing chondrichthyan teeth. Our samples are consistent with worldwide evidence that chondrichthyan crushing faunas are common following the Hangenburg extinction event. The lagoonal habitat represented by Whitrope Burn may represent a temporary refugium which is host to a near-relict fauna dominated by large crushing holocephalan chondrichthyans. Many of these had already become scarce in other localities by the Viséan and became extinct later in the Carboniferous. This fauna provides early evidence of endemism or niche separation within western European chondrichthyans at this time. This evidence points to a complex picture in which crushing chondrichthyan diversity is controlled by narrow spatial shifts in niche availability over time.
Adaptive radiation of marine crocodylians following the end-Cretaceous extinction
*Polly Russell and Nick Longrich
University of Bath, UK
The Gavialoidea, including Gavialidae and Tomistominae, are crocodilians typically recognized by their specialized snout morphology. The long, tubular (longirostrine) snout is a derived adaptation for piscivory, observed convergently in multiple crocodilian lineages. Existing fossils show this morphology to be highly conserved amongst Gavialoidea. Here we present new fossil material from the Paleocene deposits of Morocco that reveals unprecedented levels of disparity in skull shape, indicating that the gavialoid taxa staged a major opportunistic radiation in the aftermath of the K/Pg extinction. The new material includes four species. The first, a new Maroccosuchus species, exhibits robust bullet-shaped teeth and broad, blunt snout, seemingly suited for durophagy. The second, a new species of Argochampsa, shows a uniquely shortened snout and a reduced tooth count. The third is a new genus of small gharial. The fourth has a tooth count at least 50% greater than any known gharial species, with laterally projecting teeth and a hyper-elongate snout. This high disparity in the aftermath of the K/Pg extinction is mirrored in another clade of longirostrine, marine crocodilians – the Dyrosauridae. This suggests a more widespread opportunistic radiation of marine reptiles in the Paleocene, exploiting niches vacated by mosasaurs and plesiosaurs after the K/Pg extinction.
Taphonomy of keratin in archosaurs
*Evan T. Saitta, Jakob Vinther and Chris Rogers
University of Bristol, UK
Keratinous structures are common and diverse. Despite interest in feather evolution, little is known about keratin taphonomy. There is uncertainty as to what sorts of signatures keratin leaves in the fossil record and if keratin protein itself can even survive fossilization. Here, a series of decay and maturation experiments attempts to characterize taphonomic changes in a variety of Archosaurian feather and scale keratin types. These changes were examined from the chemical to the morphological level using scanning electron microscopy and pyrolysis gas chromatography mass spectrometry. Various keratin types appear to exhibit different taphonomic patterns and a series of unexpected results were retrieved. None of the observed keratin textures has been reported with confidence in fossil keratinous tissues, which only preserve remains of melanosomes and calcium phosphate salts from the keratin matrix. When maturing feathers (24 hours at 200 ˚C/250 bar and 250 ˚C/250 bar), we observe that the keratin becomes a smelly highly viscous fluid, supporting previous work showing that proteins have little or no long-term preservation potential as they fragment and become volatile. Some studies have assumed that keratins fossilize, which our experiments cast serious doubt on. Studies of archosaur integument evolution must consider taphonomic loss of the actual keratin.
Tetrapods from the Tournaisian of Nova Scotia and northern Britain: diversity, associated fauna and environmental setting
Tim Smithson1, Jenny Clack1, Jason Anderson2 and Chris Mansky3
1University Museum of Zoology, Cambridge, UK
2University of Calgary, Canada
3Blue Beach Fossil Museum, Hantsport, Canada
Tetrapod trackways have been known from the Tournaisian Horton Bluff Formation at Blue Beach, Nova Scotia, for more than 150 years. Tetrapod body fossils were first found there in the 1960s. Regular walking of the beach over the past 15 years has revealed a wealth of new material in the talus from the eroding cliffs. Many isolated limb and girdle bones have been collected, representing at least four taxa. All the remains are from similar sized animals, in the range 1–1.5 m long. This contrasts with the tetrapods discovered recently from the coeval deposits of the Ballagan Formation in the Tweed Basin of northern Britain where as many as ten new taxa have been found. Here, alongside large individuals, much smaller adult forms c. 30 cm long are present. The associated vertebrate fauna at Blue Beach includes rhizodonts, elasmobranchs, large actinopterygians and occasional gyracanthids. Lungfish are rare. This differs from the Tweed Basin fauna where gyracanthids are common, lungfish are diverse, actinopterygians are small and elasmobranchs are almost entirely absent. The Horton Bluff Formation is thought to have been deposited in marginal marine conditions, whilst the Tweed Basin Ballagan Formation probably accumulated on extensive low-relief vegetated coastal-alluvial plains.
Cracking dinosaur endothermy: palaeophysiology unscrambled
*Max. T. Stockdale1, Michael. J. Benton1 and Octávio Mateus2
1University of Bristol, UK
2Universidade Nova de Lisboa, Portugal
The amniote eggshell is a respiratory structure adapted for the optimal transmission of respiratory gases to and from the embryo according to its physiological requirements. Therefore amniotes with higher oxygen requirements, such as those that sustain higher metabolic rates, can be expected to have eggshells that can maintain a greater gas flux to and from the egg. Here we show a highly significant relationship between metabolic rates and eggshell porosity in extant amniotes that predicts highly endothermic metabolic rates in dinosaurs. This study finds the eggshell porosity of extant endotherms to be significantly higher than that of extant ectotherms. Dinosaur eggshells are commonly preserved in the fossil record, and porosity may be readily identified and measured. This provides a simple tool to identify metabolic rates in extinct egg-laying tetrapods whose eggs possessed a mineralized shell.
Assembling the Early Palaeozoic terranes of Japan
*Christopher P. Stocker1, Mark Williams1, Simon Wallis2, Tatsuo Oji3, Philip D. Lane4, Thijs R. A. Vandenbroucke5, David J. Siveter1, Derek J. Siveter6, Gengo Tanaka7 and Toshifumi Komatsu7
1University of Leicester, UK
2Nagoya University, Japan
3Nagoya University Museum, Nagoya University, Japan
4Keele University, UK
5Ghent University, Belgium
6Oxford University Museum of Natural History, UK
7Kumamoto University, Japan
The lower to middle Palaeozoic rock succession of Japan is replete with fossils that include trilobites, conodonts, ostracods and brachiopods. Various authors have suggested biogeographical relationships between these faunas and those of the Silurian and Devonian of the Australian segment of Gondwanaland and also the supposedly adjacent South China and North China plates, but there is no clear consensus on the palaeogeography of Japan at this time, and the published accounts of the fossil assemblages show no consistent patterns. In part, this reflects an incomplete record of the lithofacies distribution of the fauna, and of the palaeoecological analysis of the different faunas, which includes those with benthic and pelagic lifestyles. The South Kitakami Terrane of northeast Honshu, the Hida-Gaien Terrane of central Honshu, and the Kurosegawa Terrane of Shikoku and Kyushu islands, southwest Japan, are the three Lower Palaeozoic terranes of Japan. We provide a brief inventory of their stratigraphy and fossils, and show how new taxonomic, palaeoecological and stratigraphical studies provide a means of determining faunal affinities and, hence, keys to the early palaeogeographical position and evolution of the Japanese islands.
Heterochrony in the skulls of palaeognathae
University of Bristol, UK
The palaeognathae are one of two clades (the other being the Neognathae) comprising the avian crown group. The clade comprises the secondarily flightless ratites (ostrich, emu, rhea, cassowaries, kiwis and their extinct relatives, and the extinct elephant bird and moa); and the aerial tinamous and extinct lithornids. This study explores sequence heterochrony (changes in temporal order of developmental events) of suture closure in their skulls compared with neognath species. Heterochrony, a key mechanism in dictating organismal size and shape and the evolution of organismal form, has been linked to the evolution of birds. Birds may be paedomorphic dinosaurs and many of the diagnostic characters of palaeognaths include paedomorphic features of feathers, wings, keel-less sternum, palate, cranial sutures and pectoral girdle. Over 400 museum specimens from hatchlings to adults were observed, and closure of 20 different sutures recorded in 12 species. The order of suture closure is highly conserved across species and clades, with sutures closing from the back to the front of skull. Notable exceptions may be attributable to biomechanical stress during feeding. The age of the birds at suture closure was considered with respect to altricial/precocial behaviour and size of eye cavity.
Records of terrestrial palaeoclimate and palaeoecology of Paleocene–Eocene south-central Alaska: the Chickaloon and Arkose Ridge Formations
David Sunderlin1 and Christopher J. Williams2
1Lafayette College, Pennsylvania, USA
2Franklin & Marshall College, Pennsylvania, USA
Two non-marine Paleocene–Eocene units in Alaska’s Matanuska Valley–Talkeetna Mountains Basin contain a rich palaeoenvironmental record at a time of hothouse climate conditions. Within the Chickaloon Formation, large cupressaceous conifer trees and coal are preserved in mire depositional environments while a suite of floodplain deposits preserve leaves, shoots of conifers and equisetaleans, angiosperm fruits, and cupressaceous cones. The generally coarser Arkose Ridge Formation preserves a similar palaeoflora in rare ponded-water facies. Recent analysis of stratigraphic successions, fossil plant and insect collections, and geochemical data suggest that these units were deposited under wet and warm temperate palaeoclimatic conditions. Leaf physiognomic estimates range between 10–14 ˚C MAT and palaeoprecipitation is high as well (120-–160 cm/yr). The occurrence of palmetto fronds (Sabalites) and high seasonal wood ring production support the notion of a yearly-averaged ameliorated climate. Palaeoecological interactions between insect herbivores and dicot leaves show an unexpectedly low leaf damage frequency (~7–13%) when compared to similar studies of nearly coeval assemblages from lower palaeolatitudes on North America with only marginally higher MAT estimates. We propose that this result is related to the non-analogous situation of warm climate conditions under a high-latitude seasonal light regime.
A process-based framework for interpretation of palaeontological point distributions
Andrew R. H. Swan
Kingston University, UK
The distribution of point phenomena has customarily been analysed using the nearest-neighbour statistic: this discriminates between regular, random and clustered distributions. The scheme proposed here extends this by including a second descriptor: the coefficient of variation of nearest-neighbour distances. Point distributions can then be ordinated in the parameter space defined by these two measures. Simulations can be produced according to various hypotheses about the processes underlying the distribution of palaeontological point phenomena such as trace fossils. These hypotheses include: random, deterministic/geometrical, attraction (or positive feedback), repulsion (negative feedback), paired/grouped, and multi-phase. The predicted outcomes of these processes occupy distinctive fields in the parameter space. The analysis in this framework of real trace fossil distributions reveals differences that may assist in interpreting the organisms, the ecosystem and the sedimentary dynamics.
Testing for palaeoenvironmental preference and substrate affinity in Carboniferous echinoids
*Jeffrey R. Thompson and David J. Bottjer
University of Southern California, USA
Echinoids in modern oceans tend to occupy different substrates dependent upon their life mode, and many echinoids have evolved to live on or in certain substrates. Little is known about echinoid substrate affinities in the Palaeozoic, and rigorous testing of hypotheses regarding substrate affinities has never been undertaken. Five families of echinoids are abundant in the Carboniferous, the archaeocidarids, lepidocidarids, lepidesthids, proterocidarids, and palaechinids, which display a disparate array of morphologies, many of which may be adapted to specific substrates and life modes. In order to test for substrate affinities in these echinoids, a database was made of Carboniferous echinoids in museum collections comprising most of the known Carboniferous echinoid fossil record from America and Europe. Information on lithology (carbonate vs. siliciclastic) and grain size was recorded to test for substrate specificity in these taxa. The distribution of different clades of echinoids in the Carboniferous was then compared to the distribution of sediment types in the Carboniferous. The results show a significant affinity for carbonate sediments in all examined clades. It appears that Carboniferous echinoids preferred carbonate sediments. Additionally, specimens were scored for their taphonomic state of preservation to see how differing palaeoenvironments and depositional settings affect Palaeozoic echinoid taphonomy.
Considerations on the substitution of a type species in the case of the sauropod dinosaur Diplodocus
Emanuel Tschopp1,2 and Octávio Mateus2,3
1Università di Torino, Italy
2Universidade Nova de Lisboa, Portugal
3Museu da Lourinhã, Portugal
The ICZN accepts a morphologically undiagnosable type species for a genus, as long as the type species clearly belongs to the genus in question. This is the case in the sauropod dinosaur Diplodocus. Whereas the Code might make sense in poorly known genera, a substitution of the type species is preferable in the case of Diplodocus. Diplodocus is currently specified by D. longus. Only two caudal vertebrae and a chevron of its holotype remain reasonably complete. These can be referred to Diplodocus as generally perceived, but cannot be distinguished from other Diplodocus species based on autapomorphies. Thus, Diplodocus is specified by a nomen dubium. Diplodocus carnegii is known by the entire skeleton but the skull and the lower foreleg. Casts of its holotype are available in numerous museums around the world, and the species is generally used as reference for studies including Diplodocus. Therefore, it would make little sense to retain the fragmentary species D. longus as the type. In order to maintain Diplodocus with the generally accepted content, and provide taxonomic stability of the higher-level clades for which it is a specifier, it is preferable to substitute the current type species D. longus by D. carnegii.
FossilBlitz! Extending the BioBlitz concept to deep time
Richard J. Twitchett1, J. Alistair Crame2, Vanessa C. Bowman2, James R. Brown3, Alexander M. Dunhill4, William J. Foster5, Crispin T. S. Little4, Alistair J. McGowan6, Autumn C. Pugh4 and James D. Witts4
1Natural History Museum, London, UK
2British Antarctic Survey, UK
4University of Leeds, UK
5University of Texas, USA
6BioGeoD, Edinburgh, UK
BioBlitz events involve intense, usually time-limited, surveys of modern ecosystems undertaken by scientists and volunteers in a joint effort to document local biodiversity. Participants thus become engaged with local biodiversity issues and efficiently generate large quantities of data. As part of NERC’s 50th Anniversary Summer of Science, we extended this concept to deep time. Our ‘Jurassic FossilBlitz’ brought together palaeontologists and members of the general public of all ages for a race against the tide to find, count and record the Early Jurassic marine fossils preserved on the rocky foreshore southwest of Lyme Regis, UK. The event targeted a short sequence through the Blue Lias Formation, spanning the Hettangian/Sinemurian interval. Each individual or family group was allocated a quadrat and simple instructions to set the quadrat down randomly and to count the different fossils within it, using an identification chart. Experts were on hand to provide assistance. Some 200 individuals participated, contributing 87 quadrats and c. 1,600 fossil counts. Although primarily an outreach activity that enabled the public to collect quantitative fossil data and gain an appreciation of past biodiversity change, the data generated by FossilBlitz have some scientific value as demonstrated by comparison with published studies.
Phosphate and first principles
*Vishruth Venkataraman, Philip C. J. Donoghue and Jakob Vinther
University of Bristol, UK
Lampreys, as the nearest extant sister group to gnathostomes, provide a crucial window into the evolution of early vertebrate body plans, including the homology of cartilaginous structures. However, the impoverished fossil record, along with poor preservation of individual specimens and poor understanding of lamprey taphonomy, aggravates the potential for character misinterpretation, particularly stem-ward slippage. We describe the first ever phosphatized putative lamprey fossils, collected from the Cenomanian of Haquel and Hadjoula in Lebanon. These fossils show preservation of myomeres and evidence of axial structures, as well as degraded sarcomeres and other cellular‑level features. While phosphatization has been studied in other clades, particularly arthropods and teleost fish, preserving three-dimensional detail, our analysis, including a combination of light microscopy, UV imaging, reconstructions and SEM, reveal a novel ‘2½-D’ preservation which preserved topology without depth. Any palaeontological work must take into account pure topology without a priori assumptions of phylogenetic positioning, and falsifiable, grounded claims about synapomorphies while also considering taphonomic processes. Our work helps both understand novel preservational mechanisms in early chordates, and tests the relevance of previous work on mapping decay patterns in cyclostomes.
Solving the controversy of Earth’s oldest fossils using electron microscopy
David Wacey1,2, Martin Saunders2, Charlie Kong3 and Martin Brasier†
1University of Bristol, UK
2The University of Western Australia, Australia
3The University of New South Wales, Australia
†University of Oxford, UK (deceased)
Filamentous microstructures from the 3.46 billion-year-old Apex chert of Western Australia have been interpreted as remnants of Earth’s oldest cellular life, but their purported biological nature has been questioned on numerous occasions. Here we analyse new material from the original ‘microfossil site’ using high spatial resolution electron microscopy to decode the detailed morphology and chemistry of the Apex filaments. Light microscopy shows that the newly discovered filaments are identical to the previously described ‘microfossil’ holotypes and paratypes. Scanning and transmission electron microscopy data show that the filaments comprise chains of potassium- and barium-rich phyllosilicates, interleaved with quartz and iron oxides, plus a later carbon coating. Morphological features previously cited as evidence for cell compartments and dividing cells are shown to be carbon-coated stacks of phyllosilicate crystals. 3D filament reconstructions reveal non-rounded cross sections and examples of branching incompatible with a filamentous prokaryotic origin for these structures. At the nano-scale, the Apex filaments exhibit no biological morphology nor bear any resemblance to younger bona fide carbonaceous microfossils. Instead, it appears that these microstructures formed during fluid-flow events that facilitated the hydration, heating and exfoliation of mica flakes, plus the adsorption of barium, iron and carbon within a hydrothermal system.
A new giant species of thresher shark from the Miocene of the United States and Malta
David J. Ward1 and Bretton Kent2
1Natural History Museum, London, UK
2University of Maryland, USA
In the late Early and Middle Miocene there was burst of gigantism in a number of unrelated species of shark. This event corresponded with the warmest interval of the Neogene, the so-called ‘middle Miocene climatic optimum’, giving high oceanic productivity. In 1942, Leriche described a large species of thresher shark from the Neogene of the USA which he named Alopecias (= Alopias) grandis. The holotype was from the Miocene Calvert Formation of Nomini Cliffs, Virginia. The other was reworked from the Neogene of the Charleston area. This species is poorly known and has received little attention in the subsequent literature. An undescribed species, of similar size but with a serrated cutting edge, is present in slightly younger beds in the Calvert Formation of Calvert Cliffs, Maryland. Both species are present in the Miocene of Malta. The new serrated species has now been described and is currently in press. It is unlikely that the new giant thresher shark possessed an elongated dorsal tail lobe seen in the Recent species. As the dentition is converging on that of a great white shark and its size was similar, it is reasonable to suppose that the body outline was also similar.
An examination of feeding ecology in Pleistocene proboscideans from southern China (Sinomastodon, Stegodon, Elephas), by means of dentral microwear texture analysis (DMTA)
*Hanwen Zhang1, Yuan Wang2, Christine M. Janis1 and Mark A. Purnell3
1University of Bristol, UK
2Chinese Academy of Sciences, Beijing, China
3University of Leicester, UK
Proboscideans make interesting case studies in mammalian palaeobiology, as both fossil and extant forms show a broad and flexible range of diets, which do not always go hand-in-hand with their phenotypic adaptations. Here we present a 3D dental microwear texture analysis exploring the palaeodiet of three successive genera of proboscideans inhabiting South China during the Pleistocene: Sinomastodon, Stegodon and Elephas. Analysis of variance and pairwise testing based on textural parameters derived from scale-sensitive fractal analysis finds significant differences between Elephas and the other two genera. This is borne out by a standard anisotropy-complexity plot, which suggests that Sinomastodon and Stegodon from the Early and Middle Pleistocene were committed browsers, whereas Elephas from the Middle and Late Pleistocene shows a broader feeding niche, possibly including both browsing and grazing. The results of this preliminary study, although based on small sample sizes, are encouraging. They support previous work indicating a complex process of Pleistocene environmental changes in South China (as opposed to a unipolar trend of cooling, drying and forest deterioration), driving the succession of three characteristic faunal assemblages: Early Pleistocene Gigantopithecus – Sinomastodon fauna, Middle Pleistocene Ailuroposa – Stegodon fauna (sensu stricto), and Late Pleistocene Homo – Elephas fauna.