The Phylogenetic Performance of Morphological Partitions in Birds and Squamate Reptiles
1University of Manchester
Despite increased use of genomic data in phylogenetics, morphological information remains important for resolving evolutionary relationships, particularly for fossil species for which molecular data is unavailable. An important issue with molecular data, however, is the nature of the morphological characters themselves. Selection and evolutionary lability can make some sets of characters more prone to homoplasy than others. Moreover, when these characters evolve in semi-autonomous modules, they have the potential to overwhelm genuine phylogenetic signal contained within the data. Here we use meta-analysis of 29 published datasets to compare osteological and soft-character partitions in birds and squamate reptiles and test for different levels of homoplasy relative to molecular phylogenies. We demonstrate that non-osteological characters are marginally less consistent with molecular data in general in birds (p<0.001), but are more consistent with this phylogeny in a single, large morphological dataset. This may partly reflect different evolutionary rates or evolutionary constraints at different taxonomic levels, but in general osteological data appear to track evolutionary history better than soft characters in birds. This finding offers reassurance to palaeontologists building phylogenies of birds, dinosaurs and other reptiles, as the more readily fossilizable characters are the ones found to be more consistent with molecular trees.
The dentition of Megacephalosaurus eulerti (Plesiosauria, Pliosauridae) from the Turonian of Kansas and comments on the phylogenetic relationships of the last brachauchenines
1Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, PL-00-818 Warsaw, Poland
2Naturkunde-Museum Bielefeld, Abteilung Geowissenschaften, Adenauerplatz 2, 33602 Bielefeld, Germany
3Im Hof 9, 51766 Engelskirchen, Germany
4Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden
Megacephalosaurus eulerti was a large brachauchenine pliosaurid that roamed the Western Interior Seaway during the middle Turonian (Late Cretaceous). The type specimen (FHSM VP-321) consists of a nearly complete skull including the dentaries, and associated incomplete postcranial material. We assessed the dental morphology of Megacephalosaurus and the variability observed in its dentition. The results show that the dentition of M. eulerti was subisodont and subhomodont, with the most apparent differences observed in the development of the apicobasal ridges, which branch in some teeth. However, the taxonomic utility of this feature is debatable and perhaps depends on the part of the tooth crown where it develops. We further revised the cranial anatomy of the taxon, which allowed for a reassessment of some of its morphological characters used in recent phylogenetic studies. Our parsimony analyses inferred a single unambiguous synapomorphy uniting the node comprising mid- to Late Cretaceous brachauchenines (presence of conical teeth with a subcircular cross-sectional shape). The latest brachauchenines (Brachauchenius and Megacephalosaurus) can be also roughly characterized by reduction of their maxillary tooth count and, perhaps, a switch from anisodont to subisodont dentition. However, the phylogenetic relationships remain somewhat elusive and would probably improve following modifications in data sampling.
A graphical method for constructing raw morphospaces
1The Open University
2Smithsonian Tropical Research Institute
Morphospaces allow the forms of different organisms to be quantitatively compared, and there are two well-established approaches to morphospace construction. The first involves using a generative model to produce theoretical morphologies, while the second involves representing morphology with discrete characters and using multivariate ordination to create a morphospace of reduced dimensions. However, it is also possible to formulate a morphospace in terms of observed morphological variation but prior to any multivariate ordination. This results in a raw morphospace, which captures form by the enumeration of discrete characters but can represent both theoretical and real-world morphologies. A primary obstacle to the use of raw morphospaces in studies of organic form is the visualisation of large numbers of discrete character combinations. We have taken a computer graphics approach to this problem, and have developed tools using the Python programming language that allow collections of morphologies to be visualised as images. In these imagespaces each pixel represents a unique combination of discrete characters, and we have used this approach to study the morphology of flowers from across angiosperm (flowering plant) phylogeny, and the pollen of plants growing in tropical rain forests. We also compare our imagespaces with alternative visualisations such as multipartite graphs.
Eutrophication by biogenic phosphate pollution as a triggering factor for the collapse of obolid-dominant brachiopod communities in the early Tremadocian of East Baltica
1Golestan University, Gorgan, Iran
2Institute of Geology at Tallinn University of Technology
3National Museum of Wales, Cardiff
5Instituto de Geociencias (CSIC-UCM)
In the early Tremadocian (Cordylodus lindstromi and Cordylodus angulatus zones) the Baltoscandian epicratonic basin was environmentally heterogeneous and comprised a black shale depocentre, rimmed in North Estonia by coastal plain and shoal complexes composed of extensive brachiopod shell accumulations. By that time, nearshore obolid-dominant brachiopod communities were extinct; while allochthonous shell beds (biogenic phosphorites) were inherited relics, eroded from Furongian shoal bioaccumulations. Unlithified quartzose sand packages, exhibiting bidirectional cross laminae and commonly punctuated by thin black shale intercalations, accumulated in tidally influenced foreshore-to-shoreface settings. Nearshore reworking and condensation of sand phosphorites is a sign of coastal eutrophication, which resulted in significant seasonal enrichment of the water column by nutrients associated with dissolved oxygen fluctuations. A possible major cause of eutrophication and water pollution, coeval with widespread deposition of kerogenous clay and extinction of shallow marine biota, not previously considered, was the increase in phosphate nutrients and increased biomass of phytoplankton. Toxicity effects would be triggered by the extensive Furongian obolid shelly substrates, flooded during the marine transgression. The presence of significant amounts of dissolved phosphate in the water at that time was marked by deposition of concretions and crusts of chemogenic phosphorites outlining the periphery of the black shale depocentre.
The oldest known cheilostome bryozoan with erect colony growth from the late Albian of southwest England
1Natural History Museum
Cheilostomata are the dominant bryozoan order in modern marine assemblages. The origin of cheilostomes dates back to the Late Jurassic but the group remained low in diversity, limited in disparity, exclusively encrusting and uncommon for over 55 million years after their first appearance. Cheilostomes commenced an explosive diversification coincident with the appearance of several key novelties during the late Albian. One of these novelties – erect colony form – is found in a hitherto undescribed species common in late Albian deposits of southwest England. The new species is a chiplonkarinid cheilostome characterised by rigidly erect colonies with cylindrical, bifurcating branches. Autozooids are dimorphic, with tubular autozooids in the axial endozone covered by multiple layers of short, stacked, box-shaped autozooids in the surrounding exozone. Porous closure plates with scars of the opercular sclerites, a primitive feature lost in later chiplonkarinids, prove the cheilostome identity of this bryozoan, which is a homeomorph of a cyclostome. The new species slightly antedates the oldest erect neocheilostome species that appeared in the earliest Cenomanian, likely representing independent origin of erect growth.
This research was funded by the Leverhulme Trust (Research Project Grant ‘Molecules meet fossils – an integrated approach to studying palaeodiversity', award no. RPG-2016-429).
Classification and size distribution of scales suggest niche partitioning of an Early Cretaceous coelacanth of Las Hoyas (Spain)
1Universidad Autónoma de Madrid
2Columbus State University
3Canadian Fossil Discovery Centre
The coelacanth from the upper Barremian fossil site of Las Hoyas is the least common fish taxon from the locality but their remains suggest niche partitioning by size. Very few articulated specimens have been found (n = 10), most of them incomplete. Several isolated scales (n = 11) have also been recovered. Isolated coelacanth scales can be distinguished from other amioid-scales belonging to different taxa from the same locality (i.e., amiiforms) mainly by the presence of thick elongated ridges on the posterior field. Of all the articulated material and isolated scales, only four small individuals are represented. One articulated individual is 7cm TL, and the other three are even smaller. The most complete individual is considerably longer, measuring 20cm TL, and its scales are as long as 0.53cm in length. All isolated scales are longer than 0.53cm in length. This suggests that small individuals inhabited other environments and larger individuals might have been relatively rare visitors to the freshwater pool. The rule of survivorship suggests that small juveniles should be the most common sizes and small fishes of other taxa are very common at Las Hoyas. We hypothesize that another nearby stable aquatic environment could produce more smaller coelacanth individuals.
Preliminary taphonomic study of the carnivoran-dominated assemblage of Batallones-3 (late Miocene, Madrid Basin, Spain)
1Doñana Biological Station-CSIC (Seville, Spain)
2National Museum of Natural Sciences-CSIC (Madrid, Spain)
3Faculty of Geological Sciences, Complutense University of Madrid (Madrid, Spain)
4Geosciences Institute-UCM/CSIC (Madrid, Spain)
5Santa Elena Península State University (Santa Elena, Ecuador)
6Catalonian Institute of Palaeontology - Miquel Crusafont (Cerdanyola del Vallès, Spain)
Batallones-3 is one of the nine late Miocene mammalian sites found in the Batallones butte (Madrid basin, central Spain). Alongside Batallones-1, Batallones-3 contains an unusually large concentration of carnivoran remains: Batallones-1 hosting 98.39% of carnivoran remains whereas Batallones-3 99.58%. A total of 19,187 large-mammal remains have been retrieved, belonging to at least 15 different species. The most abundant taxa are the saber-toothed cats Machairodus aphanistus (35.92%) and Promegantereon ogygia (28.81%) and the ursid Indarctos arctoides (19.64%). Other taxa found at Batallones-3 include the hyaenid Protictitherium crassum, the amphicyonids Magericyon anceps and Thaumastocyon sp., the mustelids Eomellivora piveteaui, aff. Adroverictis ginsburgi and aff. Circamustela decheseauxi and the mephitid Promephitis nov. sp.. Remains are found in marl deposited inside a domically-shaped pseudokarstic cave, with an inferred opening in the center. Two preferential orientations of the remains are observed: outwards from the center of the cave and with a northwestern trend. However, remains appear to have suffered little to no transport, since for each species the number of density clusters correlates to the MNI. Carnivore-rich fossil sites are highly uncommon in the fossil record so their taphonomic study provides valuable insights on the origin of such concentrations.
Dinner in the Iguanodon and other Participatory Palaeo Thrills - Sparking engagement with the Crystal Palace Dinosaurs, the first extinct animals brought 'to life'.
1Friends of Crystal Palace Dinosaurs
2The Natural History Museum, London, UK
3Birkbeck, University of London, UK
4University College London, UK
5Emerald Ant, Street Theatre & Education Company
The famous Crystal Palace Dinosaurs have been thrilling visitors since their unveiling in 1854. They are the first attempts to make life-size reconstructions of the extinct animals discovered by Mary Anning, Richard Owen, William Buckland, Gideon Mantell and other pioneers of palaeontology, realised by the artist Benjamin Waterhouse Hawkins. They were the concrete manifestation of the then-new Victorian ethos that everyone can be inspired by science when it is communicated in an engaging way. As a Grade 1 Heritage Asset they still draw crowds and communicate on many levels to audiences of a wide range of sophistication, from toddlers to professional scientists. We are bringing geology, palaeontology, history and engineering to life through the interpretative lens of the CPDinosaurs. Our street theatre and education project called 'The Iguanodon Restaurant' travels to schools and festivals throughout the UK. We have produced short films in several genres: animation, humorous history, cultural documentary. We organise exciting events on site. The Friends of Crystal Palace Dinosaurs (http://cpdinosaurs.org/) are working to restore the sculptures, landscapes and build a vibrant outreach programme around these surprising heritage features. These 'stupendous monsters' retain their ability to release your imagination and evoke a sense of ancient lives and landscapes.
First record of the mosasaurine mosasaur Carinodens from the uppermost Maastrichtian of Stevns Klint, Denmark
2Natural History Museum of Denmark
3Natuurhistorisch Museum Maastricht
5Naturalis Biodiversity Center
6Faculteit Aard- en Levenswetenschappen
The small durophagous mosasaurine mosasaur genus (Reptilia, Mosasauridae) Carinodens is exceedingly rare in north European chalk deposits, with published finds limited to a small number of shed tooth crowns and two partial dentaries from the Netherlands and Belgium, all assigned to Carinodens belgicus. A newly discovered isolated, presumably shed, tooth crown from the UNESCO world heritage site of Stevns Klint expands the known geographical distribution of another species, C. minalmamar, first described from Morocco, to Denmark. The specimen was found within the uppermost metres of the Maastrichtian chalk deposits, thereby placing it within the last 50.000 years of the Cretaceous. The new tooth crown represents the northernmost occurrence of the genus Carinodens. Previous finds of mosasaur dental and skeletal materials from Denmark have been assigned to the hypercarnivorous mosasaurids Mosasaurus hoffmannii and Plioplatecarpus sp. Thus, the new specimen provides important new information on ecological niche partitioning amongst large marine reptiles during the latest Maastrichtian.
Revealing rangeomorph species characters using spatial analyses
1Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
2Department of Earth Sciences, Memorial University of Newfoundland, St. John’s, NL A1B 3X5 Canada
3British Geological Survey, Nicker Hill, Keyworth, Nottingham NG12 5GG, United Kingdom
Rangeomorphs dominate the Ediacaran Avalonian macrofossil assemblages of Charnwood Forest, UK (~565Ma). However, their unfamiliar fractal architecture makes distinguishing phylogenetically reliable characters from intraspecific features difficult. Fortunately, spatial analysis of large in-situ populations of such forms offers an independent means of assessing their taxonomy. Populations of a single biological species are likely to exhibit similar spatial distributions due to their shared responses to the biological and ecological processes acting upon them: if two named ‘species’ differ by a single morphological character, but exhibit the same spatial distributions, then that character is unlikely to be taxonomically significant and more likely represented an ecophenotypic response. As such, spatial analyses can be used to interrogate which are the most taxonomically deductive characters between similar species. We used Random Labelling Analyses to permutate the presence/absence of characters of Primocandelabrum boyntoni, P. aethelfalaedia and P. aelfwynnia from North Quarry ’B’ surface. The resultant spatial distributions were compared using goodness-of-fit tests to determine which characters were associated with unique populations and which were found across multiple populations. Our results suggest that ecophenotypic characters are prevalent within the rangeomorphs, and need to be taken into consideration when defining species.
Using synchrotron tomography to elucidate the anatomy of early land plants
2University of Bristol
3University of Leicester
4Swiss Light Source, Paul Scherrer Institut
The evolutionary relationships between the lineages of living bryophytes and vascular plants are still not fully understood. No consensus has yet been achieved from phylogenetic analyses alone. Living bryophytes exhibit a complex mosaic of anatomical characters that are difficult to distinguish between convergence and common descent. To determine the sequence of early land plant character evolution it is therefore essential to study early embryophyte lagerstätten, e.g. the Rhynie Chert. One of the oldest and most diverse assemblages of early embryophytes is from Lower Devonian strata at Brown Clee Hill, Shropshire, in which plant anatomy has been preserved to cellular level by charcoalification. Studies spanning the last 20 years have revealed this to be rich assemblage of early tracheophytes and a group of plants that possess both tracheophytic and bryophytic characters. While the charcoalification process has preserved these plants by converting them to chemically inert material, resistant to bacterial decay, these rare fragments are highly brittle. Traditionally they have been physically sectioned, and in many cases only fragments of the original specimens remain. Computed tomography provides a non-invasive and non-destructive alternative approach. Here we present Synchrotron Radiation X-ray tomographic microscopy of Lower Devonian charcoalified embryophytes from the Swiss Light Source, Switzerland.
Soft-tissue preservation in the upper Silurian Leintwardine Beds of Leintwardine, Herefordshire
1Department of Natural Sciences, Amgueddfa Cymru – National Museum Wales, Cathays Park, Cardiff CF10 3LP, UK
2Nanjing Institute of Geology and Palaeontology, 39 East Beijing Road, Nanjing 210008, China
3Department of Geology, University of Leicester, Leicester LE1 7RH, UK
4Palaeobiology, Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario M5S 2C6, Canada
5Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario M5S 3B2, Canada
6Menara Shell, 211 Jalan Tun Sambanthan, 50470 Kuala Lumpur, Malaysia
The upper Silurian submarine canyon deposits of Church Hill, Mocktree and Martin’s Shell, Leintwardine (Herefordshire, UK), are famous for their diverse, exceptionally preserved echinoderms (mainly asterozoans) and sclerotised but non-biomineralised arthropods (eurypterids, phyllocarids and xiphosurans). These taxa, and rare palaeoscolecidan worms, are preserved with an exceptional degree of articulation, but no labile tissues have been described. Examination of material housed in Ludlow Museum (Shropshire, UK), as part of the Fossils in Shropshire (FISH) documentation project, has revealed previously unrecorded organisms from this biota, including exceptional preservation of soft tissues and soft-bodied organisms. The strata at Church Hill contain polychaete worms (with gut traces), sponges, benthic graptolites and algae. In addition, an arthropod from Mocktree is preserved with biramous limbs. This expanded Leintwardine assemblage has affinities with previously described Konservat-Lagerstätten from North America and Estonia.
A reappraisal of the Early Cretaceous margaritierid Margaritifera (Pseudunio) valdensis (Mantell 1844)
1Dinosaur Isle Museum
2Museo Geominero Instituto Geológico y Minero de España
Margaritifera (Pseudunio) valdensis from the Early Cretaceous Wealden Group of southern England, and contemporaneous rocks in France and Spain, was originally described as thick-shelled, oval, critically lacking a ventral sinus. In 1961 Mongin revised the taxon into the extant genus Margaritifera, subgenus Pseudunio. However, in 2015 Van Damme et al. confirmed the validity of the over-looked genus Paraheudeana Starobogatov, published in Russian in 1970, with M. valdensis, as the type, a revised diagnosis, based in part upon an ellipsoid-ovate outline (Margaritifera, is elongate-oval) and the absence of a ventral sinus.
This study re-examines the type series, recognising them as incomplete specimens lacking critical posterior portions of the shell. The lectotype, superficially oval in outline, has a shallow, but distinct ventral sinus, seemingly out-grown, the broken ventral margin not preserving actual shell shape or the commissure. Significantly, many other specimens confirm the presence of the ventral sinus and elongate-oval outline. Combined with diagnostic characters such as mantle pits, we retain the species in the genus Margaritifera. However, doubt surrounds Pseudunio, in 2016 Araujo et al. reviewing the phylogeny of the Margaritiferidae, concluded only the genus Margaritifera was valid, discounting Pseudunio as a valid genus or subgenus.
Taphonomic controls on melanin-bearing tissues from river lamprey (Lampetra fluviatilis).
1University of Leicester
2University of Bristol
Melanin is a ubiquitous pigment that is found in numerous tissues across a wide range of taxa. Melanin plays a pivotal role in a variety of biological and ecological functions, such as protection from ultraviolet radiation and camouflage patterning. Recently, palaeontological studies have used evidence of fossilised melanin and the organelles that produce it - melanosomes - to infer ecological adaptations of extinct taxa and to help resolve the phylogenetic placement of several enigmatic species. However, the in vivo characteristics of melanin-bearing tissues and their melanosomes in extant taxa are not fully resolved. Moreover, little is known about how the pigment within these tissues is affected by decay, crucial to understanding the preservation potential of such tissues. Here we present preliminary data showing the distribution and characteristic morphology of melanin and melanosomes throughout tissues in river lamprey (Lampetra fluviatilis) during several stages of decay. Initial results suggest that different tissues contain characteristic melanosome morphologies and distribution of melanin, and that the distribution of pigment within L. fluviatilis is affected by decay. Understanding these effects is critical to successfully interpreting pigmentation patterns in comparable fossil taxa, and the ecological or phylogenetic implications that can be drawn from them.
First evidence of tetrapod burrowing from the Lower Triassic of Sardinia: implications for understanding survival in Permo-Triassic equatorial extreme conditions.
1Imperial College London
2University of Birmingham
A new burrow cast is described from the Early Triassic of the Cala Viola Formation, North-West Sardinia, and is tentatively associated with a terrestrial tetrapod, possibly cynodont or procolophonid excavator. Comparisons of architectural morphology between Permo-Triassic and extant burrows, finds that several similarities occur between the structure of subterranean excavations created by non-mammalian therapsids. The three-dimensional cast is cautiously identified as a complex burrow system, indicating gregarious behaviour of its inhabitants and a subterranean mode of life. The burrows likely represent distal terminal chambers of a burrowing system, due to their elliptical domed shape and lack of bilobate ventral surface. A paucity in tetrapod burrows from this period means that the new Sardinian specimen provides significant insight to our understanding of adaptations by early Mesozoic vertebrates to challenging palaeo-environmental conditions. We integrate our ichnological and palaeoecological observations with lithostratigraphy, thanks to a new highly detailed revised stratigraphic section of the locality, postulating that the occurrence of a burrow within such close proximity of the Permo-Triassic boundary, indicates a close relationship between the evolution of burrowing and the onset of harsh climatic conditions.
Taphonomic controls of ubiquitous phosphatisation of soft tissues in Sirius Passet, North Greenland
1University of Bristol
2British Geological Survey
3Korea Polar Research Institute
4University of Copenhagen
Sirius Passet is an early Cambrian Konservat Lagerstätte situated in North Greenland. It is one of the least studied of the ‘great three’ Cambrian localities with exceptional preservation that includes the Burgess Shale and Chengjiang. However, Sirius Passet is unique for its density of exceptional fossils as well as its preservation. Muscle tissue and intestinal tracts are commonly preserved in three dimensions in black mineral, which is surmised to be derived from calcium phosphate. The high amount of phosphatisation is unique for Sirius Passet, but the depositional context for its preservation is poorly understood. Here we present a taphonomic model for the ubiquitous preservation through phosphate. Microbial mats are ubiquitous in Sirius Passet and form coherent and patchy sheets on most bedding plane surfaces. Microbial mats are commonly seen in other localities with exceptional preservation, such as the Solnhofen Plattenkalk, and may have acted as sealing barriers limiting diffusion and as a source of phosphate from decaying organic material. Other factors that most likely played a role is evidence for high primary productivity in the water column. Modern zones of upwelling are responsible for current phosphate deposits. We also highlight an apparent taxonomic bias in phosphatisation and discuss its correlation.
New occurrence of the blastozoan echinoderm Felbabkacystis in the mid-Cambrian of the Skryje–Týřovice Basin (Czech Republic)
1Charles University, Prague
2Géosciences Environnement Toulouse
The primitive blastozoan echinoderm Felbabkacystis was recently described from the Drumian Jince Formation (Příbram-Jince Basin, Barrandian area, Czech Republic). This unique echinoderm is important for studying the relationships and evolutionary history within the early blastozoans. Felbabkacystis shows a specific morphology of its body plan. This genus is considered as a transitional form between calyx-bearing and theca-bearing blastozoans. The aim of this contribution is to report a new occurrence of this blastozoan echinoderm from the lower to middle levels of the Drumian Buchava Formation (Skryje–Týřovice Basin, Barrandian area, Czech Republic). Finds of blastozoans are generally rare in the Buchava Formation. Only two genera have been known from this unit: Lichenoides and Luhocrinus. Felbabkacystis specimens are preserved as internal and external moulds in sandy greywackes. The type of preservation is not as good as in the Jince Formation. All studied material is deposited in the collections of the Czech Geological Survey, Prague.
MicroCT and 3D modelling of Ophiderpeton brownriggi and Dolichosoma emersoni: implications for aïstopod evolution and ecology.
1Trinity College Dublin
The Pennsylvanian (Langsettian) Jarrow assemblage in Ireland is home to two species of aïstopod, Ophiderpeton brownriggi and Dolichosoma emersoni. First described in 1866, little work has been done on them despite major revisions of the order Aïstopoda at the start of the century. This is due to the poor appearance of the specimens and the pyrite decay of the holotype of D. emersoni. Four specimens, two O. brownriggi and two D. emersoni, were scanned using microCT. Three of the resulting datasets where then rendered in Spiers. The presence of tightly packed gastralia and dorsal ovoid osteoderms in D. emersoni indicate that it is an immature Ophiderpeton rendering the former species invalid. Thus, the first occurrence of two separate aïstopod species co-inhabiting an ecosystem is pushed up to the Linton Assemblage (Asturian).
Growth series of O. brownriggi indicates that near complete ossification of both the cranium and the post cranium occurs at an early stage, a common characteristic among the “Lepospondyli”. Several bones ossify at a later stage, including the ribs on vertebrae C1-C3 which maybe a result of the need to accommodate a relatively large skull growth. 3D models provide a more accurate description of Ophiderpeton brownriggi.
Digital technology restores stolen fossils at Joint Mitnor Cave, Devon
1Natural History Museum
2University of Birmingham
3William Pengelly Cave Studies Trust
4University of Manchester
Joint Mintor Cave is a SSSI and the type site for the Joint Mitnor Cave Mammal Assemblage Zone. Excavations of the 120,000 year old site revealed an exceptionally rich interglacial fauna, including an unusual mix of African game and temperate woodland animals. An unexcavated section of these deposits, including the remains of straight-tusked elephant, brown bear and spotted hyaena, has been maintained since 1962 by the William Pengelly Cave Studies Trust as an educational resource. Vandalism of the site in 2015 resulted in the theft of surface specimens and damage to the section. This sparked a collaborative effort to restore the site.
Specimens, similar to those stolen, were identified from the Natural History Museum (London) collections using photographs of the site before vandalism. The specimens were CT scanned to produce high resolution digital replicas, and used subsequently to develop detailed 3D prints to replace the stolen specimens. These objects were also integrated into Virtual Reality Cave database.
This highly successful collaborative project, using expertise from different specialists and institutions, opens up new avenues for using 3D data from museums’ collections. It also highlights some of the current issues with security and conservation of heritage sites such as Joint Mitnor Cave.
What is your Rate? EarthRates—a New Research Coordination Network for Linking Scales Across the Sedimentary Crust
1University of Connecticut
2Lamont-Doherty Columbia University
3University of Minnesota
4University of Wisconsin
A Research Coordination Network “EarthRates: Linking Scales Across the Sedimentary Crust” has recently been funded by the US NSF to provide the framework and opportunity to engage critical communities and forge new collaborations in order to foster transdisciplinary research in Earth’s sedimentary crust. We will bring together community-driven entities such as the Paleobiology Database, Neotoma, Macrostrat, EarthTime, EarthChem, Earth-Life Transitions, the Continental Scientific Drilling Coordination Office, and Flyover Country, to strategize, leverage and build partnerships and collaborative efforts to enable the geoscientific community to address major grand challenges in Earth system science. These include how have the oceans, the Earth’s sedimentary crust, carbon sinks and soils, and life itself evolved together, and what does this tell us about the future trajectory of the integrated Earth-life system? and what are the ranges of ecosystem response, modes of vulnerability, and resilience to change in different Earth-system states? By bringing these groups together and building stronger partnerships and alliances, we will move towards the goal of developing a fully integrated four-dimensional digital Earth to fully understand dynamic Earth system evolution. We are looking for international partners and collaborators in this effort.
Quantifying the hydrodynamic performance of the Cambrian arthropod Isoxys using computational fluid dynamics
1University of Oxford
2University of Lausanne
3Oxford University Museum of Natural History
Isoxys, a Cambrian nektonic bivalved arthropod, is known from over 15 species with diverse forms, from the relatively symmetrical and short-spined type species Isoxys chilhoweanus, to the more asymmetrical long-spined Isoxys longissimus. The shape of the bivalved carapace must have influenced the drag and lift forces experienced by Isoxys as it travelled through the oceans, impacting on the energy requirements of the animal to move through and up and down in the water column.
Two-dimensional models of Isoxys chilhoweanus and Isoxys longissimus were created and computer simulations of fluid flow carried out in ANSYS Fluent, using angles of attack ranging from 0° to 25°. The results show that Isoxys chilhoweanus generated higher drag than Isoxys longissimus. The lift generated by Isoxys longissimus increased with the angle of attack, but the opposite pattern was seen for Isoxys chilhoweanus, with lift decreasing as the angle of attack increased. This suggests that Isoxys species with longer spines and more asymmetrical carapaces were better able to move horizontally and vertically within the water column than forms with shorter spines.
Earthquakes and Palaeontology. A case of shallow and deeper marine environment mixing from Crete (Greece).
1National & Kapodistrian University of Athens, Faculty of Geology and Geoenviroment, Dept. of Historical Geology - Paleontology
2National & Kapodistrian University of Athens, Faculty of Geology and Geoenviroment, Dept. of Geophysics - Geothermics
The latest Zanclean eastern Mediterranean molluscan record is revealed through the study of a 60m thick stratigraphic sequence near the village Voutes (Heraklion Basin, Crete, Greece). Forty-two species of bivalves and gastropods have been identified, 31.7% of which are no longer present in the Mediterranean. Bathyal zone deposits were recognized by the macrofaunal analysis. Strong mass-wastings were found to have formed a series of sand lenses on the lower part of the section. These lenses have distinctive sedimentological attributes and contain a fauna typical of coastal zone. The origin of these mass-wasting deposits has long been enigmatic but could be related to an uplift which started in Crete as early as ca 5 Ma (latest Zanclean). These possibly earthquake-triggered sandy slides indicate the transportation of material from the coastal zone to the upper bathyal zone. Sand lenses contained molluscs indicate the infra to circalittoral zone, as biocoenoses of vegetated and gravelly bottoms were recognized.
Some of the most characteristic bivalves of bathyal zone as Leda clavata, Ledella nicotrae, Yoldia nitida, Bathyarca philippiana, Limea strigilata and Kelliella ruggierri are reported in the Pliocene of Greece for the first time.
Ecology of brachiopod and mollusc assemblages across the Early Toarcian (Early Jurassic) extinction event in the Lusitanian Basin, Portugal
22. MARE and Departamento de Ciências da Terra Universidade de Coimbra
The ecological changes across the Early Toarcian warming/extinction event were assessed through a detailed bed-by-bed study of brachiopods and bivalves assemblages from the marlstones and micritic carbonates of the ca. 28 m thick Fonte Coberta/Rabaçal section in the Lusitanian Basin, Portugal. Comparison of the taxonomic composition of pre- and post-extinction assemblages reveals an almost complete faunal turnover in brachiopods and a less severe one in bivalves. The pre-extinction assemblages are dominated by brachiopods whereas in the post-extinction assemblages bivalves are more abundant, yet small-sized. The diversity, highest in the pre-extinction interval, reaches the lowest values in the ca. 1.3 meters below the extinction level. The post-extinction diversity is otherwise comparable to the average diversity values observed in the pre-extinction. The ecological structures before and after the extinction are unrelated unlike the crisis interval assemblages, which are still related to the pre-extinction phase.
Wolff's law and terrestrialization: structure/function adaptation
The lifestyle of extinct tetrapods is often difficult to assess without clear adaptations such as swimming paddles. For example, the external anatomy of salamanders gives no data about their lifestyle. According to the Wolff's law, the trabecular bone architecture follows the principal stress trajectories generated from external loads. Theoretically, a terrestrial tetrapod will show a marked main trabecular orientation, while an aquatic tetrapod will show a trabecular orientation more isotropic. The Wolff's law has been extensively studied in mammals and birds, but rarely in reptiles and amphibians. These animals with transverse posture like that of first tetrapods have various lifestyles (aquatic, amphibious and terrestrial). We will scan their humeri and analyze many trabecular parameters: spacing, thickness, anisotropy and connectivity. Finite element analysis (FEA) reconstructs stress, strain and deformation in a digitalized structure. A new concept, the 'inverse Wolff law's', consists in inferring from the trabecular bone architecture the magnitude, direction and distribution of contact forces at the articular surface. From the 3D reconstruction of a bone microarchitecture, we will solve an optimization problem yielding the articular forces satisfying a target value of homeostasis. This concept tested on living species could allow inferring lifestyles of extinct species.
Revisiting the affinities of Chancelloriids: Are they sponges after all?
1Deparment of Earth and Environmental Sciences, Paleontology and Geobiology & GeoBio-Center, Ludwig-Maximillians-Universität.
Chancelloriids are one of the most mysterious groups of Cambrian problematica. Their body fossils are remarkably similar to cactuses, having a club-shaped morphology dotted with rosettes of hollow sclerites. They were originally described as primitive sponges in the early twentieth century but later studies showed notable similarities in the fine structure of their sclerites and those of some stem group molluscs, casting doubt on the original interpretation. Depending on whether the sclerite structure is reconstructed as a synapormophy or as a plesiomorphy, chancelloriids are interpreted as aberrant stem molluscs, the coeloscleritophora hypothesis, or as early diverging eumetazoans. Despite the loss of popularity of the sponge affinity hypothesis, recent reinterpretations of the anatomy of a group of Cambrian sponges might be able to rekindle it by providing a potential link between chancelloriids and protomonaxonids. Here we review the arguments proposed for and against the sponge interpretation and assess them in the context of poriferan evolutionary morphology.
The Sedimentology and paleontology of the Lower Cambrian Withycombe Farm Borehole, Oxfordshire, England
*Kendra Power1, Liam Herringshaw2, Alex Liu3, Duncan McIlroy1
1 Memorial University of Newfound
2 University of Hull
3 University of Cambridge
The pre-trilobitic lower Cambrian of the Withycombe Formation is a 194 m thick siliciclastic succession dominated by interbedded offshore red-purple and green pyritic mudstones with minor sandstones. The mudstones contain a hyolith-dominated small shelly fauna including: orthothecid hyoliths, hyolithid hyoliths, the rostroconch Watsonella crosbyi, early brachiopods, the foraminiferan Platysolenites antiquissimus, the coiled gastropod-like Aldanella attleborensis, halkieriids, gastropods and a low diversity ichnofauna including evidence of predation by a vagile infaunal predator. The assemblage contains a number of important index fossils (Watsonella, Platysolenites, Aldanella and the trace fossil Teichichnus) that enable correlation of strata around the base of Cambrian Stage 2 from Avalonia to Baltica. The pyritized nature of the assemblage has enabled the study of some of the biota using micro-CT, augmented with petrographic studies, revealing pyritized microbial filaments of probable giant sulfur bacteria. We aim to produce the first complete description of the core and the abundant small pyritized fossils preserved in it and develop a taphonomic model for the pyritization of the “small” shelly fossils.
Textures of exceptional preservation – quantitative analysis based on 3D characterization of surfaces
1University of Leicester
In many Lagerstätte, exceptional preservation of non-biomineralised tissues is linked to particular modes of mineralization – early authigenic phosphatization, for example. But in some cases, exceptionally preserved fossils do not exhibit detectable compositional differences from the matrix; the boundaries of the organism and thus the shape of the body are unclear. Similarly, in specimens that exhibit changes in colour relative to matrix, external haloes linked to chemical changes around a decaying carcass can cause problems in anatomical interpretation. Here we test the hypothesis that exceptionally preserved fossils exhibit surface textures that are quantitatively distinct from those of the surrounding matrix. Our tests are based on statistical analysis of parameters derived from ISO 25178 Characterisation of Areal Surface Texture. The results reveal that in a number of Lagerstätte there are clear and significant differences between matrix and fossils, providing additional evidence where anatomical boundaries are uncertain, and a new source of taphonomic data. Furthermore, variation in texture between different body parts within fossils provides a guide to differences between the original tissues from which anatomical characters were constructed.
Aragonite and pyrite preservation in ammonites from Jurassic mudrocks.
2National Museum Wales
Aragonite and pyrite both contribute to ammonite preservation in the Jurassic mudrocks of Dorset (Charmouth Mudstone Formation). Nacreous aragonite is scarce but recorded from three genera and four species of Lower Liassic ammonites. Preservation of original bio-mineralic aragonite consistently occurs in the posterior of the body chamber of ammonite fossils confirming a palaeobiological influence in its survival through the Taphonomically Active Zone. Nacreous aragonite preservation outlines the soft tissue attachment areas. Their consistent position and extent suggest that locally increased shell thickness promoted survival of an otherwise vulnerable component in the depositional environment.
Pyrite preservation is more abundant, found as the internal moulds of ammonite fossils. Petrographically diverse pyrite replacement textures show predictability through position in the body chamber and phragmocone. Density increases adapically and an evolution from equant to aggregated pyrite suggests more complete pyritisation. Internal sedimentation and inclusion of exotic fauna within body chambers indicate bottom water currents. Amorphous external pyritisation and obscured surface detail result from syn-replacement fracturing of fragile components and subsequently, a more readily available sulphate supply. Complementary sedimentological data suggest pyrite formation persisted in reducing microenvironments in variable sea bottom oxygenation.
New look at London Clay sponge crabs: original material reconsidered
1CR2P UMR 7207, Sorbonne Universités, Muséum national d'Histoire naturelle, Université Pierre et Marie Curie, CNRS, Paris, France.
2Oertijdmuseum De Groene Poort, Boxtel, the Netherlands.
3Naturalis Biodiversity Center, Leiden, the Netherlands.
The Dromiidae, also known as sponge crabs, are one of the earliest families of Brachyura. Since their presumed apparition in the Jurassic their significant occurrence during the Eocene epoch triggered the descriptions of well-known fossil species yielded from the London Clay deposits (England) within the two last centuries. The here proposed study is based on a simple observation: the original material which allowed the description of the Eocene crab species Dromilites bucklandii (H. Milne Edwards, 1837) from the Isle of Sheppey differs from all the material subsequently described as such. It actually corresponds to a less common species, with a rather flat carapace, which has been described much later as a new species: D. simplex. Here, we demonstrate that this latter species has actually to be considered as D. bucklandii and we create a new Dromilites n. sp. This new taxa includes all the fossil crabs, displaying a more ornamented carapace, that have been mistakenly identified as D. bucklandii for 180 years. We show, by providing good imaging (e.g. photogrammetry) of ancient non-figured and new well-preserved material, that these two species differ genuinely one from another, regardless of the growth stage of the carapaces.
Structure and Growth of Heterostracan Bodywall Extensions and the Evolution of Vertebrate Paired Fins
1University of Bristol
2University of Manchester
Paired appendages, alongside jaws, are a key component of the gnathostome bodyplan, yet their evolutionary origin has long courted controversy. Palaeozoic jawless vertebrates show an array of fin-like structures, however, this debate has often neglected the significance of the ability to extend the bodywall laterally. This is a key innovation which must, paradigmatically, underpin the origin of paired fins. We investigate the nature of the earliest lateral bodywall outgrowths, found in heterostracans, and find their structure and perceived development shares fundamental similarities to the dorsal spine in the same taxa. We propose spine growth begins with a rounded tubercle which splits medially, allowing apposition of successive generations of tubercles. This process is facilitated by resorption, which also allows thickening of a compact vascular layer, possibly strengthening the spine. This implies that heterostracan skeletogenesis is more dynamic than previously suggested. We also reconstruct the distribution of paired bodywall outgrowths and find that lateral bodywall extensions appear to have arisen independently at least twice in early vertebrate history. This leads us to suggest that a fin competency region may have been duplicated as early as 542 million years ago.
Life inside a dinosaur bone: a thriving microbiome
1University of Bristol
3Royal Tyrrell Museum
4University of Bath
5Foundation for Scientific Advancement
6Revive & Restore, The Long Now Foundation
7Johns Hopkins University
9University of York
Dinosaur bone has been hypothesized to contain endogenous organics such as collagen, osteocytes, and blood vessels. However, proteins and labile lipids are unstable through diagenesis and deep time; bone is also an open system, allowing organic and microbial influx. Organics within fossil bone of appreciable age/thermal maturity producing ‘vessel’- and ‘cell’-shaped molds have alternatively been identified as biofilm. Here, chemical and biological analyses of freshly-excavated, aseptically-acquired, Late Cretaceous dinosaur bones and sediment controls show a thriving microbiome. Pyrolysis GC-MS pyrograms of the fossil bone do not match modern, collagen-containing bone. Amino acid composition of the fossils does not match collagen and is L-amino-acid-dominated, suggesting recent amino acid input. Interestingly, amino acid, DNA, and organic carbon concentrations are higher in the fossil than the surrounding mudstone matrix, suggesting the presence of a microbiome. Further microbial community characterization by 16S rRNA amplicon sequencing reveals the predominance of Actinobacteria and Proteobacteria in the bone. Sequences affiliated with the classes Nitriliruptoria and Deltaproteobacteria were more abundant relative to the adjacent mudstone. Fossil bone likely provides an ideal, nutrient-rich (e.g., phosphate, iron) microbial habitat inside vascular canals capable of moisture retention, suggesting caution regarding claims of dinosaur bone soft tissue.
Selective taphonomic processes in the Fezouata Konservat-Lagerstätte (Lower Ordovician, Morocco): storm influence on the brachiopod record
1LGL TPE - UMR5276 - ENS de Lyon
2Department of Natural Sciences, National Museums Scotland
Taphonomic processes are responsible for the transition of an organism from the biosphere to the lithosphere. In marine settings, these processes involve both pre-mortem and post-mortem biological, chemical and physical parameters in the water column and in the sediments. Previous detailed studies focused on the influence of these parameters on the fossil record (Lilliput effect, fossil sorting, presence of mineralized organisms). The pre-mortem physical conditions of the water column, however, have not been considered important. The brachiopod record in the Fezouata Shale suggests that these physical processes should be taken into consideration to explain the size composition of the brachiopod assemblages. In this Formation, epibenthic brachiopods show an abnormal distribution (small-sized individuals only) in proximal sites and a normal demography in distal localities, while the distribution of endobenthic brachiopods was standard in both proximal and distal sites. This discrepancy can be related to storm intensities influencing the Fezouata palaeoenvironments. In shallow settings, living epibenthic brachiopods were more influenced by weak storms than deeply-burrowing endobenthic taxa, which were only affected by stronger events. This indirect ecological defense strategy provided more time for endobenthic individuals to grow, therefore displaying a wider range of sizes in proximal settings than epibenthic communities.
The effect of acidification on D. majorinum (Mollusca: Scaphopoda) in the Southern Ocean.
1University of Bristol
2British Antarctic Survey
Polar oceans are projected to be highly affected by warming and ocean acidification making the Antarctic continent an ideal test laboratory. Regional differences in temperature and carbonate chemistry due to the different oceanography make Weddell and Amundsen Sea ideal test setting in which to assess biotic response to different environmental conditions. Here we focus on an understudied group the Scaphopoda specifically Dentalium majorinum. We found differences in morphometric parameters such as ventral and dorsal diameters, length and rib number, volume and densities. On average, the Amundsen sea specimens are smaller in length and volume than the Weddell sea specimens. Length, ventral and dorsal diameter are higher at depth below 1600m depth in the Weddell sea. Internal difference in shell morphology are been analysed by microtomography (microCT) and synchrotron based x-ray tomographic microscopy (SXRTM). No distinct growth rings, indicating difference with growth rates between winter and summer, are visible in the specimen.
A Trilobite from the Lower Lower Cambrian Reveals Structure and Function of an Ancient Compound Eye
1University of Cologne
3University of Edinburgh, Scotland
Fascinating relicts of highly differentiated compound eyes have been described from the Lower Cambrian. They show dense lattices of hexagonal arrangements, reminiscent of compound eyes of modern bees, dragonflies or certain crustaceans. No convincing evidence, however, has been given so far about the internal structures, different possibilities for simple arrangements of sensory equipment may be envisaged. Alternatively an ommatidium may have lain below each lens, as in modern crustaceans, insects and xiphosurans. Here the light is concentrated by a dioptric apparatus (lens or lens cylinder and a crystalline cone) onto a light-guiding rhabdom. The latter is part of the sensory cell system by which it is surrounded. The sensory units are isolated against each other by a pigment screen, so each ommatidium provides one 'pixel' collectively producing a mosaic-like image.
In the holotype of the phosphatised trilobite Schmidtiellus reetae Bergström, 1973, the right eye is slightly abraded and shows the internal structures of the visual units. It shows the typical ommatidial principle, however, there is no lens, and each unit lies in a separate kind of 'cellular basket'. It is shown that this system worked without a lens properly as a compound eye, more than half a billion years ago.
Preliminary study of bioclaustration cases from Devonian of Asturias
1Natural History Museum
3The College of Wooster, Ohio
This is a study of some bioclaustration cases from the Early Devonian of North Spain. The Aguión Formation (Emsian) in Asturias displays an exquisite preservation, although recrystallized, for a variety of embedment structures resulted from overgrowth of different symbionts by bryozoans (mostly fistuliporids and trepostomes). Sectioned specimens allow for observation of growth of bryozoan zooecia adapted to the morphology of the embedded organisms. These bioclaustration structures are described and included in preliminary groups according to the taxa represented in the associations and the morphology of the embedment structure. The identified bioclaustration cases were caused by growth of bryozoans associated with both skeletonised and soft-bodied symbionts, skeletonised biota being represented by rugose corals and soft-bodied taxa by unidentified vermiform animals.
We suggest that the rugose corals grew in symbiosis with the fistuliporid bryozoans. The association is apparent when observing that the inner surface of the calices are not encrusted by the fistuliporid bryozoans. The tubes of unidentified soft-bodied organisms secreted by their host bryozoans seem to indicate that a few trepostome species sheltered vermiform symbionts that lived and grew in association with their host.
The ‘Great Ordovician Biodiversification Event’: a rapid, spectacular explosion of diversity or an extended mosaic of ecological and taxonomic expansion?
1Universite de Lille, UMR 8198 Evo-Eco-Paleo
2Durham University, UK
Some authors have considered the ‘Great Ordovician Biodiversification Event’ (GOBE) as a spectacular, short-lived ‘event’ representing a massive increase in the diversity of marine organisms during the Middle Ordovician. This concept is based on a restricted view by authors focusing on a single fossil group, possibly on a single palaeocontinent. John (Jack) Sepkoski established, in the 1970s and 1980s, the statistical reality of the Ordovician radiation, a term promoted by Droser et al. (1996) in their seminal paper ‘The Ordovician Radiation’. The ‘GOBE’ was defined by Webby (2004), based on Sepkoski’s concept, as the sum of many individual events. The GOBE includes several Biotic Immigration Events (BIMEs), such as the ‘Richmondian Invasion’ and the ‘Boda Event,’ but also successive biodiversity pulses including a succession of diversifications in the planktonic (late Cambrian - Early Ordovician), level-bottom benthic (Early-Middle Ordovician) and reef communities (Middle-Late Ordovician), although the boundaries of these ‘events’ are diachronous (as for the entire GOBE). The GOBE is thus an aggregate of the diversity trends of all individual fossil groups displaying rapid increases, diachronously, during different intervals and across different regions.
Ichnotaxonomy of a sporadically-exhumed dinosaur tracksite: the Cretaceous Lee Ness Sandstone, East Sussex
1University of Cambridge
New dinosaur footprint finds have been reported from the Wealden exposed in the cliffs near Hastings on 37 occasions dating back to 1846, when a single imprint was first presented to the Geological Society of London. These finds all occurred along a stretch of coastline approximately 18 km long, between Cooden to the west and Fairlight to the east. Typically the footprints are observed in collapsed blocks of cliff material sourced from several key horizons, the most lucrative of which is the Lee Ness Sandstone of the Ashdown Beds Formation.
We present an ichnotaxonomic list of the vertebrate and invertebrate ichnofauna of the Ashdown Beds Formation. The sporadic and periodic exhumation of the tracks by cliff retreat attests to the tracks occurring in patches on the base of the Lee Ness Sandstone, despite them being found singularly. Estimates of the rate of cliff retreat are used to interpret the spacing between trackways. Due to occurring at the same stratigraphic level, the ichnofauna provides a key snapshot of the dinosaur and invertebrate fauna living on the floodplain of a Cretaceous meandering river.
Mandibular eco-morphology reveals how dietary specialisation shaped synapsid macroevolution following the Permo-Triassic mass extinction event.
1University of Bristol
Synapsids experienced great taxonomic and ecological success through the Permian, and dominated terrestrial ecosystems, but were severely impacted by the Permo-Triassic mass extinction. Diversity of surviving clades (Anomodontia and Eutheriodontia) recovered quickly, but ultimately fell through the later Triassic, with archosaurs taking over as the most diverse and abundant clade. The macroevolutionary drivers of the transition have been debated, whether it resulted from intrinsic archosaur “competitive superiority” or the extrinsic impact of the extinction. Here we provide an eco-morphological perspective, assessing synapsid macroevolution from the Late Permian to the Early Jurassic. We use geometric morphometric methods to plot mandibular disparity and morphospace through time, using mandibular feeding functionality to infer patterns of trophic ecology and evolution. Our results reveal a novel pattern of eco-morphological decline across the Permo-Triassic that suggests dietary specialisation did not necessarily reduce survivability through the extinction event. Furthermore, we find contrasting patterns of trophic evolution within surviving synapsids that sheds further light on the recovery of terrestrial ecosystems following the extinction. Our study favours an extrinsic driver of synapsid macroevolution through the early Mesozoic, and illustrates how investigations of macroevolution benefit from consideration of morphological, as well as traditional taxonomic approaches.
Comparative Synarcual Morphology in Extant and Extinct Batoids (Skates and Rays; Chondrichthyes)
1Natural History Museum
Batoidea (skates, rays; Chondrichthyes) comprise approximately half of all Elasmobranchii and are the most morphologically diverse members of this group, inhabiting most marine ecological niches. Characteristic featurees include dorsoventrally depressed body and the synarcual, a tessellated cartilaginous tubular structure comprising fused anterior vertebrae. A comparative study of synarcual morphology among extant (computed tomography) and extinct batoids (macrophotography) examines how structural variation reflects function, including locomotion and feeding. Batoids with pectoral fin-based locomotion (e.g., Raja clavata) have stronger, shorter synarcuals, and a reinforced neural tube inside the synarcual supporting the large pectoral girdle, dorsally attached via the pectoral arch. Axial-based batoids (Rhinobatos formosensis, Rhina ancyclostoma) have an anterior-posteriorly longer synarcual, reinforcing rigidity along the axial skeleton, but with a less robust pectoral arch and less expansive fin span. Some batoids (Narcine tasmaniensis) show a combination of features, using pectoral and axial locomotion. Extinct batoids have shorter synarcuals and robust pectoral arches, indicating pectoral-based locomotion; which appears to be the plesiomorphic condition in early batoids. Feeding involves cyclic dorsoventral cranial movement in N. tasmaniensis, with the synarcual providing rigidity and support; R. formosensis uses the anterior body to trap prey against the substrate.
Traquair’s lungfish from Loanhead: dipnoan diversity and tooth plate growth in the late Mississippian.
1University of Cambridge
2University of Edinburgh
R H Traquair, the eminent palaeichthyologist and museum curator, procured an extensive collection of Palaeozoic fishes from across Scotland with the help of local miners and quarrymen. One productive locality near Edinburgh was Loanhead. He described numerous fossil fish from this Serpukhovian site, including four lungfish taxa: Ctenodus interruptus; Sagenodus quinquecostatus; Uronemus splendens; and Ctenodus angustulus. The first three are quite well known but the fourth was only briefly described and never figured. A fifth taxon, Conchopoma sp., has recently been identified. This is the earliest known occurrence of the genus, extending its range into the Mississippian. The presence of five lungfish at a single locality is unprecedented in the Carboniferous and indicates that the high level of lungfish diversity encountered in the Tournaisian of the Scottish Borders continued throughout the Mississippian. This may have been due to changes in tooth plate growth enabling greater variation in dentition and diet. Tooth plate growth in most Devonian taxa can be explained by comparison with that in extant forms, but analysis of Carboniferous tooth plates suggest growth was different in many taxa, allowing for novel patterns of tooth ridges and different types of teeth to develop on the same plate.
Intraspecific variation and evolutionary trends in conodonts
*Louise Souquet1, Pauline Guenser1, Nicolas Goudemand1
1Institut de Génomique Fonctionnelle de Lyon (IGFL), École Normale Supérieure, UMR5242, CNRS, Université Claude Bernard, Lyon, France
How shape changes through time? The set of theoretically possible forms is bounded by the way they can be generated during ontogeny, possibly driving evolution into preferential directions.
Patterns of shape variation in conodont elements have been documented mostly qualitatively and at the species level, no generalized pattern of variation has been described. Because conodont elements are used for feeding, their complex morphology may reflect functional adaptations to specific diets. Yet, they must also reflect developmental constraints. It is thus mandatory to understand if and which traits might be adaptive or not. Conodont elements are likely highly integrated, that is their morphological characters are not independent but covary with each other. In this study, we investigate patterns of intraspecific variation in two very distinct and distant assemblages, one from the Late Devonian, and one from the Late Triassic. In both cases, empirical observations have led some authors to hypothesize evolutionary trends in conodonts morphology. Here we are assessing those ‘trends’ in a quantitative way. For this purpose, we have 3d scanned hundreds of elements from both assemblages and investigated quantitatively patterns of variation and covariation with geometric morphometric analysis.
The energetics of marine calcification under ocean acidification
1California Institute of Technology
2University of California Berkeley
The marine fossil record is dominated by the calcium carbonate skeletons of past organisms. Ocean acidification events in the geological record have impacted the diversity of marine calcifiers, and anthropogenic ocean acidification threatens numerous ecologically important modern taxa. However, the metabolic demand of skeletal manufacture is poorly understood hampering accurate forecasts of extinction risk. In this work, we develop a generalized mathematical framework to delineate the fundamental costs faced by organisms in precipitating shells out of seawater. We show that the energetic demand of inorganic, calcium carbonate is typically less than the organic matrix used as a template in skeletons, limiting whole-shell cost sensitivity to values less than roughly 10-20%. Instead, we highlight the importance of rate, as opposed to cost, in determining the extinction risks of marine organisms. We discuss the central importance of larval mortality and discuss key future experiments that may help inform the differential extinction risks.
Atmospheric pCO2 decreased prior to the sudden O-isotope change at the Eocene-Oligocene boundary
1Swedish Museum of Natural History
A unique collection of fossil leaves belonging to species Eotrigonobalanus furcinervis (extinct trees of the beech family, Fagaceae) from a stratigraphic sequence in central Germany was utilised to derive an atmospheric pCO2 record with the stomatal proxy method. The record comprises multiple data points spanning the late middle to latest Eocene, two sampling levels which may be earliest Oligocene, and two samples from later in the Oligocene. The new record indicates that pCO2 decreased continuously by ca. 40% in the late middle to late Eocene, from ca. 630 ppm to ca. 410 ppm at the Eocene-Oligocene boundary. Based on the subsequent records, pCO2 in later parts of the Oligocene was similar to latest Eocene values. A significant drop in pCO2 at the Eocene-Oligogene boundary is not observed, in contrast to marine oxygen isotope records. These results may suggest that: 1) decrease in pCO2 preceded the large shift in temperatures and/or ice sheet expansion that characterizes the Eocene-Oliogocene boundary, probably when a certain threshold of pCO2 was crossed; and 2) that pCO2 levels – and thus this climate change threshhold – were lower than previously assumed, suggesting important implications for estimations of climate sensitivity
*Christopher Stocker1, Phil Lane2, Derek Siveter3, Gengo Tanaka4, Toshifumi Komatsu5, Mark Williams1, Tatsuo Oji6, Simon Wallis7
1Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH, UK
2School of Geography and Earth Sciences, Keele University, Staffordshire, ST5 5BG, UK
3Oxford University Museum of Natural History, Parks Road, Oxford, OX1 3PW, UK
4Institute of Liberal Arts and Science, Kanazawa University, Kakuma-machi, Kanazawa City, Ishikawa 920-1192, Japan
5Graduate School of Science and Technology, Kumamoto University, 2-39-1, Kurokami, Kumamoto 860-8555, Japan
6Nagoya University Museum, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
7Department of Earth and Planetary Sciences, Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
Trilobites are widely represented in the Silurian and Devonian strata of Japan, with taxa described from the South Kitakami, Hida Gaien and Kurosegawa Palaeozoic terranes. Here present a review of five of the trilobite groups represented in the Japanese Siluro-Devonian sequences: Illaenida, Scutelluidae, Phacopidae, Proetida and Encrinuridae that have received recent taxonomic revision. The proetids suggest an endemic signal at species-level, not just between Japan and other East Asian terranes, but also at the level of the individual Japanese terranes; Silurian illaenids and scutelluids show multiple genus and species-level links with the Australian segment of the Gondwana palaeocontinent, but not between the Japanese terranes; encrinurids also suggest possible species-level links with Australia, and also between the Japanese terranes; and Devonian phacopids suggest links with the North China palaeocontinent. These markedly different patterns may in part reflect the fragmentary biostratigraphical record of the Japanese trilobites, but also appear to be explicable in terms of the facies ranges and ecology of the different groups. This cautions against the use of the Japanese trilobite assemblages for biogeographical assessment without reference to their autecology and facies distribution, an assessment of which should give a clearer understanding of their true palaeogeographical significance.
Endocranial morphology of Powichthys thorsteinssoni Jessen and the phylogeny of early Stem-group Dipnoi (Osteichthyes, Sarcopterygii)
1University of Bristol
2Imperial College London
Resolving phylogenetic uncertainties within the lungfish stem is crucial to understanding early sarcopterygians and osteichthyan evolution. Powichthys thorsteinssoni is one of the earliest known sarcopterygian taxa, from the Early Devonian Drake Bay locality, Prince of Wales Island, in Arctic Canada. Powichthys possesses a fused dermal cranial joint, which has been suggested as an incipient stage in lungfish cranial fusion. However, competing hypotheses place P.thorsteinssoni as either a porolepiform, the sister group of all other total-group dipnoans, or as a more proximate relative of the crown than porolepiforms. Here we add phylogenetically useful data on the endocranial morphology of P. thorsteinssoni using x-ray computed microtomography. We observe an elbow-like hypophysial chamber is present as in P.spitsbergensis. Similarly to P.spitsbergensis and Youngolepis, the pituitary vein foramen is more anterior than in porolepiforms. Nasal capsule morphology resembles that of Porolepis. The interpretation of pores on Jessen's 'mushroom structure' as lacunae suggests P.thorsteinssoni possession of ventral processes, a proposed Powichthys autapomorphy. Phylogenetic analyses suggest that P.thorsteinssoni is more closely related to Youngolepis and Diabolepis than Porolepiformes.
How well do environmental parameters preserved in the geologic record describe benthic ecological niches?
Ecological niche modelling (ENM) is an emerging technique in modern macroecology for the quantitative prediction of species distributions based on abiotic environmental parameters. The PaleoENM framework has laid the groundwork for the application of ecological niche modelling to the fossil record, opening an exciting research frontier for understanding interactions between biodiversity and environmental changes in deep time. The palaeontological record, unfortunately, does not directly record many of the abiotic environmental variables utilized by benthic marine ecology models in the modern ocean. In this study, we address the potential of indirect environmental signals available in the geologic record to parametrize the ecological niche space of modern benthic macroinvertebrates by applying machine learning methods to large oceanographic and biodiversity datasets from the benthic ecosystems of Southern California. Random forest algorithms are employed to evaluate the potential of the geologic record to predict modern ecological distributions in the absence of direct oceanographic variables, focusing on bathymetry, sedimentology and geochemistry. Through this approach, we hope to advance understanding of how geologically available parameters relate to modern ecological processes and assess the proportion of ecologically relevant environmental information preserved in the geologic record.
Global Paleobiogeographical Patterns and Correlations in the Palm Macrofossil Record
Palms (Aracaceae/Palmae) are an important component of some modern and ancient forested terrestrial ecosystems. Dominantly tropical in distribution today, their macrofossil record extends back to Cretaceous time and, during some periods, into polar paleolatitudes. While there has been much recent work on the evolution, systematics, historical ecology, and biogeography of modern palms, what deserves more study is the global macrofossil occurrence of this group from leaf, fruit, axis, and inflorescence remains.
More than 300 palm macrofossil occurrences from over 220 localities reported in the published literature were collected in a database of taxonomic (genus, species, and/or form) and locality (formation, literature age, age constraint, preservation lithology, modern geographic coordinates, paleogeographic coordinates) data.
These data show the greatest paleolatitudinal extent of the palm macrofossil record to be during Early Paleogene time (spanning >100 latitudinal degrees). The data also show a bimodal paleolatitudinal concentration in the northern and southern subtropics when totaled across Cretaceous to Recent occurrences, in line with marine carbonate and evaporite lithofacies distributions.
Understanding the paleobiogeographical record of these iconically tropical plants (in the modern world) can help elucidate Earth’s paleoclimate, paleoecological, and paleoenvironmental history in ancient worlds and provide context for modern and future climate change.
Fossil micrometeorites hidden within acid-digestion residues
1Imperial College London
2The Natural History Museum, London
Disrupted asteroids and sublimating short-period comets produce a continuous flux of submillimetre extraterrestrial dust. This material, termed micrometeorites, spirals into the inner solar system and is either captured by terrestrial planets or consumed by the Sun. On Earth, infalling micrometeorites become incorporated into actively forming marine sediments and are ultimately preserved in the geological record. Thus, palaeontologists searching for microfossils, have unknowingly collected, extracted and curated an abundance of micrometeorites, which today remain hidden within acid digestion residues. In this study we explore several conodont residues for cosmic dust. Although the yield of micrometeorites recovered is relatively small, the initial rock samples analysed were also modest. By contrast, several systematic large-scale micropalaeontology projects have previously dissolved significantly larger samples, even exceeding 100kg. From such projects, an interdisciplinary collaboration re-examining the detrital remains would generate vast numbers of cosmic spherules, thereby providing a significant contribution to our collective understanding of the extraterrestrial flux over geological time and the formation of asteroid families. The aim of this presentation is to highlight the potential for further research into micropalaeontology residues as collection sites for micrometeorites.
New data about inner morphology of petrosum of Miocene baleen whale Vampalus sayasanicus from Chechnya
1Paleontological Institute A.A. Borissiak RAS, Moscow
2NRC Kurchatov Institute, Moscow
Vampalus sayasanicus is very interesting Miocene baleen whale from Chechnya and very differs from other typical Cetotheriidae (i.e. typical cetotheriinae and herpetocetinae). We scanned the right cochlea of V. sayasanicus. The specimens were scanned in NRC "Kurchatov Institute" by using "Kurchatov synchrotron radiation source" and "Research reactor IR-8". A spatial resolution was 130 μm for synchrotron tomography and 160 μm for neutron tomography. Recovered virtual sections have been morphological described by neutron data because a strong contrast on the rock that filled some cavities (or small crystals grown in these cavities) was observed on synchrotron data. The 3D model was obtained by synchrotron data ready. The result found that the cochlea has approximately 3.25 turnover, which differs from herpetocetinae - 2.5-2.75 turns (Park et al., 2017), Cetotheriinae – about 2.7 turns (Tarasenko et al., 2017). Earlier V. sayasanicus was considered to herpetocetinae (Tarasenko et Lopatin, 2012), but the new data of the morphology of the petrosum, some morphological features of the external morphology of this bone, make it necessary to revise the taxonomic position of this whale.This work was supported by the FRP RAS Biodiversity of Natural Systems. Biological resources of Russia: assessment of state and fundamental principles monitoring ".
Petrosal bone Upper Miocene Odontoceti from Northern Ciscaucasia (Krasnodar region and Adygea)
1Paleontological Institute of Borissiak RAS, Moscow
Three petrosal bone from the late Miocene of Northern Ciscaucasia (locality near Gladkovskaya and a number of locality in Adygea) are close in morphology to samples from the lower Serravalia Visiano (Clayey quarry, Northern Apennines, Parma, Italy), described as Acrodelphidae or Delphinidae (see Gigala-Fulgosi, Pilleri, 1985, Table 6, Figures 1-6). However, the Caucasian samples, in comparison with the Visiano samples, have a more robust and shortened anterior process, and also a relatively smaller opening of aqueductus cochleae. We scanned and investigated petrosal bone from smaller toothed whales in the Paleontological Institute of Russian Academy of Sciences, on the X-ray micro-CT Skyscan 1172. Microtomography parameters: I=100 mA, U=103-104 kV, a filter – Al (1 mm), a pixel size was from 25 to 34.1 μm, a rotation - 180º, steps of rotation were 0.7º, random movement – 10, frame averaging – 8. TView, NRecon, CTAn programs are used. As a result of the work, it was possible to describe in detail the morphology of the reconstructed virtual sections and construct a 3D model of the labyrinth of the petrosal bone. This work was supported by the FRP RAS Biodiversity of Natural Systems. Biological resources of Russia: assessment of state and fundamental principles monitoring.
The strange case of a Silurian fish fossil from the Kalana lagerstätte, Estonia
1University of Tartu, Estonia
22Tallinn University of Technology, Estonia
The Kalana Lagerstätte of the Silurian age (Aeronian, Llandovery) in Estonia has revealed rich exceptionally preserved non-calcified algal flora. The faunal fossils in Kalana display a rich biota, within which benthic, nektic and planktic faunas are all well represented. However, the preservation of different groups, depending upon their lifestyle and skeletal mineralogy, is rather variable. The excellent preservation of some fossils, e.g. crinoids suggests that they were buried in situ. Yet a considerable proportion of shelly fossils, including brachiopods and gastropods, are common in storm accumulated coquina lenses. Gastropods, as a rule, are preserved as internal moulds only.
A recent discovery of an agnathan head shield is a remarkable addition to the species list. This specimen belongs to Osteostraci, and as the earliest member of the group, pushes back the timing of the assumed origin of the clade by about 10 million years. The elemental analysis performed with EDS in order to determine the chemical composition of the dorsal head shield, revealed that instead of the supposed major constituent of the dermal skeleton - calcium phosphate – the fossil consists of carbonaceous matter only. The missing of phosphate in the fossil is extraordinary, especially taking into consideration that the locality yields also conodonts, which show normal preservation.
Foraminiferal reaction to changes in Pliocene climate
1University of Bristol
2US Geological Survey
Anthropogenic atmospheric carbon dioxide (pCO2) is rapidly rising. This increase is impacting on the ocean, affecting the biological pump, ocean chemistry and marine organisms. Marine calcifiers are affected by increased CO2, but future consequences are still unknown. We quantify the relationship between changing environmental conditions and calcification in foraminifera, a group essential to the biogeochemical and carbon cycle during the Pliocene. The Pliocene was the last time interval when atmospheric CO2 concentrations were comparable to today. We measured the test size of planktic foraminifera and the weight of the dominant species Globigerinoides ruber through the Pliocene at Ocean Drilling Program Site 999 in the Caribbean. Test size shows high-frequency variability not related to carbonate chemistry or to temperature, as these are generally stable at Site 999 during this interval. During marine isotope stage M2, foraminiferal test size increases and may have been linked to changes in stratification in response to the closure of the Panama Isthmus. From ongoing observations, foraminiferal weight is larger at higher temperatures and thereby for inference higher CO2. CT scans will be used to distinguish the driver of the observed changes such as wall thickness changes or increased number of chambers on the weight of foraminifera.
Cosmine means cosmine: morphology and phylogeny of sarcopterygian dermal tissue
1University of Chicago
Cosmine has traditionally been described as a sarcopterygian synapomorphy consisting of a single enamel layer overlaying a series of pore cavities connected by underlying canals in dentine. The discovery of such pore canals in several actinopterygian taxa have caused confusion about the definitive structure and phylogenetic signature of cosmine. We used synchrotron tomography to generate the first three dimensional model of cosmine in Megalichthys hibberti, the taxon cosmine was originally defined in. Accompanied by studies on the cosmine of the dipnomorph Porolepis, we propose that cosmine is indeed an informative rhipidistian synapomorphy. Ancestral state reconstruction further suggests that cosmine is a specific elaboration of an older osteichthyan pore canal system important for vascular supply through the dermis. This study provides a new framework for studying sarcopterygian relationships using specific structural differences in the pore canal systems, while also helping further clarify the positions of enigmatic basal osteichthyan taxa.
Mica-agglutinating worm tubes from the Upper Ordovician of Tafilalt, southeastern Morocco
1Edge Hill University
2Amgueddfa Cymru - National Museum of Wales and Nanjing Institute of Geology and Palaeontology.
3Amgueddfa Cymru - National Museum of Wales
4University of Missouri
A small number of organisms create exoskeletons not through biomineralisation, but rather through agglutination: binding sedimentary particles from their environment in a cement or organic matrix. Most agglutinating organisms use any and all materials available, but a small proportion show greater selectivity, for particle size or particle kind.
Here, we describe fossils from Ordovician strata of the Tafilalt region in southeastern Morocco which appear to be agglutinated tubes composed wholly of muscovite mica. Mica-agglutinating fossils have previously been described from the Cambrian of Estonia and the southwestern United States of America under the generic name Onuphionella, and interpreted as polychaete worm tubes.
We investigated the Moroccan fossils through microscopy and SEM analysis. These are similar to Onuphionella in their tubular form and micaceous mineralogy, but differ in a number of important respects. Most particularly, the mica flakes in the Moroccan material are arranged parallel to the tube length, rather than perpendicular as in Onuphionella; the Moroccan specimens also differ in width (smaller), length (longer), and flexibility (evidently much higher, with some specimens folded back on themselves). The specimens all appear to be lying flat on bedding plane surfaces, but are not current aligned, making palaeoecological and taphonomic interpretation puzzling.
A new species of Parotodus (Lamniformes: Otodontidae) from the Oligocene of Japan
1NHM London, UK
2Nagasaki Dinosaur Museum, Nagasaki, Japan
3NHM London, UK
The genus Parotodus Cappetta 1980 is a lamniform shark ranging from the Eocene to the Pliocene. Its teeth are rare and are usually found in mid to outer shelf deposits. In Japan it occurs in rocks of early Oligocene to late Pliocene age.
Three fossil shark teeth were collected from the Yukiaino Sandstone Member, Karatsu Formation in Saga Prefecture, south-western Japan. They were referred to the genus Parotodus because they could be distinguished from other lamniform sharks by the following combination of characters: absence of serrated cutting edges; presence of broad neck; U-shaped basal edge of the root and development of the lingual protuberance of the root.
These teeth were originally identified as Parotodus benedenii (Le Hon 1881), a Neogene species, based on their size and lack of lateral cusplets. However, two specimens possess a small pair of lateral cusplets similar to the middle Eocene species P. mangyshlakensis Kozlov 1999. Given that an increase in size and the progressive loss of lateral cusplets are a trend in Parotodus, we hypothesize that our specimens and some early Oligocene specimens described from Belgium by Leriche (1910) are a new species intermediate in morphology between P. mangyshlakensis and P. benedenii.
A first insight into macroflora from the Early Devonian (Emsian) of the Holy Cross Mountains, Poland.
1University of Silesia, Faculty o Earth Sciences, Department of Palaeontology and Stratigraphy
New macroflora data has been obtained from Bukowa Góra Quarry, western part of the Łysogóry Region of the Holy Cross Mountains. The formation consists of several dozen meters of sandy facies interbedded with thin mudstones and siltstones interpreted as a near shore (lagoon to shelf) paleoenvironment. The macroflora remains were found in mudstones intercalations. The fossil material includes impressions of plant stems, roots, charcoalified vascular strands, but also cuticles, as well as abundant spores. Preliminary study reviled presence of fragmented stems resembling Taeniocrada sp. with characteristic central xylem strand and branching Hostinella-like remains. Samples processed for palynology unveiled a great diversity of plant cuticles with stomata preserved, isolated tracheids of different types and fungal hyphae. Palynological examination allowed to assigned samples with macroflora to the douglastownense-eurypterota Zone (Emsian/Eifelian). Important miospore taxa found include Emphanisporites spp., Hystricosporites corystus, Grandispora douglastownense, Ancyrospora spp., Dibolisporites spp. and Retusotriltes spp. The lack of Ancyrospora eurypterota indicates that the age is not older than Emsian. Plant fossils are accompanied by numerous and diverse arthropods remains.
The research were financed by the NCN grant 2015/19/B/ST10/01620.
A new site with Pleuromeia remains from the late Buntsandstein of the Holy Cross Mts, Poland.
1Department of Palaeontology and Stratigraphy, Faculty of Earth Sciences, University of Silesia, Poland
2Naturmuseum Bozen, Bolzano/Bozen, Italy
3Department für Geo- und Umweltwissenschaften, Paläontologie und Geobiologie, Ludwig-Maximilians- Universität, and Bayerische Staatssammlung für Paläontologie und Geologie, Munich, Germany
Pałęgi claypit are already known from numerous arthropods remains: conchostracans, cycloid crustacean and insects. Exposed siltstones, mudstones and sandstones of the Late Buntsandstein age (latest Olenkian-early Anisian) represents fluvial deposits and have yielded also bivalves, invertebrate ichnofossils as well as vertebrate bones and foot tracks. Until now plant fossils were mentioned only within stratigraphic context. Palynological expertise showed that deposits from Pałęgi claypit can be correlate with latest Olenkian-early Anisian units of the German Basin. Macrofloral remains are preserved as compressions and casts. Present are vegetative plant organs (leaves, stems and roots) along with reproductive structures: seeds, sporangia, cones. Our recent study reviled the presence of the floral assemblage consisting of lycophytes, horsetails, ferns and conifers. The most abundant are remains resembling Triassic plant from the genus Pleuromeia. Characteristic features of the fossils are suggesting the similarity of Polish specimens to Pleuromeia sternbergi from Bundtsandstein of Germany. Pleuromeia is the most important and typical plant from the Buntsandstein of the Germanic or Central European Basin. That would be the first complete description of that taxa from Triassic of Poland.
The research were financed by the NCN grant no 2014/15/N/ST10/05142
Persistence of shallow dwelling Cenozoic isocrinid crinoids in the Southern Hemisphere: implications for the Marine Mesozoic Revolution
1British Antarctic Survey
4The University of Western Australia
5Royal Botanic Gardens Victoria, Australia
Increased predation pressure as a result of the Marine Mesozoic Revolution (MMR, starting ~200 million years ago) shaped the ecological structure of benthic sea floor communities from the Mesozoic to the Recent. It has been argued that less mobile groups such as stalked isocrinids moved out of shallow water environments by the Late Cretaceous (100–66 million years ago) to evade increased predation pressure. Newly collected and described taxa from Antarctica and Australia, supplemented by data gathered from the literature, demonstrate a substantial Southern Hemisphere fossil record of stalked isocrinid crinoids (Order Isocrinida), which inhabited shallow water until the Eocene/Oligocene boundary (~34 million years ago). These occurrences, from often overlooked isolated crinoid columnals, as well as newly discovered articulated crinoid fossils, challenges the perceived notion that the majority of stalked crinoids became restricted to deep water in the mid-late Mesozoic. The delayed migration of the Southern Hemisphere isocrinids to deeper waters after the Eocene/Oligocene boundary may have been due to intraorder competition from the more motile comatulids, which became dominant in the Southern Hemisphere following major ocean circulation changes including the onset of the Antarctic Circumpolar Current.
A new, basal actinopterygian from Nova Scotia: stem group survivorship in the early Carboniferous
1University of Calgary
The vertebrate fossil record of the earliest Carboniferous is notoriously poorly-sampled, obscuring a critical interval in the evolution of modern vertebrate diversity. Recent studies of diversity across the Devonian-Carboniferous boundary propose a vertebrate mass-extinction at the end-Devonian, and recent phylogenetic and molecular work suggests that the origin of the actinopterygian crown may have occurred in the earliest Carboniferous, as part of a broader recovery fauna. However, the data necessary to test this are limited. Here, we describe a partial actinopterygian skull, including diagnostic elements of the posterior braincase, from the Tournaisian Horton Bluff Formation of Blue Beach, Nova Scotia. The braincase surprisingly shows characters typical of Devonian taxa but absent in Mississippian forms, such as an open spiracular groove, open ventral cranial fissure, anteriorly-restricted parasphenoid, and lateral dorsal aortae that pass through open groves in the ventral otoccipital region. Phylogenetic analysis places it deep within the actinopterygian stem, among Devonian moythomasiids and mimiids, suggesting broader survivorship of plesiomorphic actinopterygians across the end-Devonian mass extinction. With high lineage survivorship in tetrapods and lungfish across the Devonian-Carboniferous boundary and high vertebrate diversity at other Tournaisian localities, this hints at a more gradual turnover between Devonian and Carboniferous vertebrate faunas.
Palaentology and stratigraphy of an exceptionally fossiliferous spherule-rich bed at the Cretaceous–Paleogene (K–Pg) boundary in Mississippi, USA: implications for events before, during, and after the K–Pg mass extinction
1American Museum of Natural History
2Earth and Environmental Sciences, Brooklyn College, 2900 Bedford Ave, Brooklyn, New York, USA
3Earth Sciences, University of Southern California, Los Angeles, California, USA
4Department of Earth and Planetary Sciences, University of New Mexico, Alberquerque, New Mexico, USA
5United States Geological Survey, Reston, Virginia, USA
6Institute of Marine and Coastal Sciences, Rutgers University, Piscataway, New Jersey, USA
7School of Marine and Atmospheric Science, Stony Brook University, Stony Brook, New York, USA
We describe an outcrop of the Cretaceous–Paleogene (K–Pg) boundary in Union County, Mississippi, USA, consisting of the Owl Creek and overlying Clayton formations. The Owl Creek Formation is rich in the ammonites Discoscaphites iris and Eubaculites carinatus. These indicate the D. iris Assemblage Zone and deposition in the final 300 kyr of the Cretaceous, confirmed by microfossil analysis. The base of the Clayton Formation marks the K–Pg boundary, and consists of a 15-30 cm thick muddy, poorly sorted quartz sand that contains abundant and well-preserved 0.5 mm to 1 mm-sized impact spherules, derived from the Chicxulub crater 1500 km to the south. The spherule bed contains a rich macrofossil fauna of 35 species of molluscs, echinoid fragments, and crab and shark remains. The infill of mollusc shells is identical to the surrounding matrix (including spherules) and differs from the underlying Owl Creek. This suggests the animals were either alive or loosely scattered on the sea floor at the time of deposition. A combination of geochemical and sedimentological analyses suggests multiple environmental and depositional changes during the K–Pg interval in the Gulf Coast. These can be related to both the Chicxulub impact and longer term environmental variability.
Reconstructing trophic networks across the early Toarcian Ocean Anoxic Event (Lower Jurassic)
1School of Earth and Environment, University of Leeds
2School of Biology, University of Leeds
Trophic guild diversity, connectivity, and robustness of trophic networks decreases across the Early Toarcian Ocean Anoxic Event. We focus on the reconstruction of trophic network dynamics across the early Toarcian extinction event; which is thought to have been driven by an Ocean Anoxic Event. The analysis is based on a field database collected from the Pliensbachian-Toarcian of the Yorkshire Coast, with 162 macrofossil species assigned to trophic guilds using the Bambach ecospace model. Although there is limited evidence for the decoupling of pelagic and benthic ecosystems, there is a major loss of motile, metabolically demanding benthic fauna. Network connectivity is greater in the late post-extinction recovery than in pre-extinction, although the number of guilds remain equal. This is likely due to the appearance of new predatory guilds that display a high degree of centrality, i.e. well connected to other nodes, in the networks. The results suggest that the early Toarcian extinction event was likely a top-down extinction with metabolically demanding benthic guilds, such as motile predators, disappearing during the Ocean Anoxic Event, as they were more sensitive to dysoxic and anoxic conditions than stationary benthic faunas with lower metabolic demands.
The early Cambrian origin of Pancrustacea revealed by micro-computed tomography
1University of Cambridge
3Massachusetts Institute of Technology
4Carl Zeiss (Shanghai) Co. Ltd
The early evolution of Pancrustacea is mainly informed by exceptional Cambrian microfossils preserved as three-dimensional phosphatic replicates in Orsten-type assemblages, or as flattened ‘small carbonaceous fossils’ (SCFs) from organic-rich shales. Although these taphonomic windows capture minute anatomical details, their preservation potential is strictly limited to larval stages (Orsten) or recalcitrant fragmentary remains (SCFs), precluding direct comparisons with macroscopic taxa from Burgess Shale-type deposits. We employ X-ray computed tomography to reveal the exceptionally preserved three-dimensional appendicular anatomy of the bivalved euarthropod Ercaicunia multinodosa from the Cambrian (Stage 3) Chengjiang Lagerstätte in China. The head comprises four differentiated appendage pairs, including well-developed antennules with sensorial setae, hook-shaped antennae composed of three robust podomeres, subquadrate serrated mandibles, and subtriangular maxillules with a multiarticulated distal palp. The gnathal limbs surround an oval-shaped hypostome. The trunk bears 16 pairs of biramous appendages. Each trunk limb consists of an endopod with five to nine podomeres with rounded endites, a three-segmented exopod with posterior-facing setae, and a proximal leaf-shaped epipodite attached to the basipod. The appendicular organization of E. multinodosa indicates affinities with stem-group Pancrustacea, with comparable implications for morphologically similar bivalved euarthropods from early and middle Cambrian Burgess Shale-type biotas such as clypecaridids, waptiids and hymenocarines.
A review of Loxodonta atlantica (Pomel, 1979) based on newly identified materials from the Muséum national d’Histoire naturelle (Paris, France)
1University of Bristol
2Natural History Museum, London
Among the two surviving genera of extant proboscideans, the African elephant Loxodonta has been long-held as the more evolutionarily conservative taxon. However, discussions over the deep-time evolution of this lineage remained unsatisfactory due to the presence of few identifiably diagnostic fossil materials. We hereby report previously unpublished craniomandibular elements of Loxodonta atlantica from the Pleistocene of Algeria, the most morphologically derived species from the genus, and one of the very largest. The specimens were collected during expeditions led by Camille Arambourg and now housed in the collections of the Muséum national d’Histoire naturelle, Paris, France. The rediscovered Algerian materials allow a thoroughly emended diagnosis for the poorly discussed species. The craniomandibular morphology of L. atlantica supports its attribution to the genus Loxodonta, but a few noticeable autapomorphies preclude it from the ancestral lineage leading to the extant Loxodonta species: L. africana and L. cyclotis. These systematic inferences are supported by a preliminary cladistic analysis.
A new marine snake (Palaeophiidae) from the early Paleogene of Morocco, a signal of early Cenozoic diversification
1University of Bath
The early Cenozoic phosphates of Morocco have yielded a diverse marine vertebrate fauna. Among these are the Palaeophiidae, a group of large to giant marine snakes. Previously, all Palaeophis specimen from Morocco have been identified as P. maghrebianus. We describe a new palaeophiid from the Palaeocene/Eocene boundary of the Oulad Abdoun basin. The fossil consists of disarticulated vertebrae and ribs, and is referred to the family Palaeophiidae based on the horizontal axis of the cotyle-condyle, the low position of the synapophyses, the long and slightly curved ribs, and lateral compression of the vertebrae. It differs from primitive palaeophiid snakes and resembles Pterosphenus in exhibiting a hypertrophied neural spine, which extends to twice the length of the centrum on trunk vertebrae, and in the pterapophysis protruding slightly over the dorsal height of the zygosphene at a low angle. Parsimony analyses based on 29 characters and 24 fossil snake taxa suggests a relatively derived form with affinities to the Pterosphenus clade. The specimen illustrates the extreme aquatic adaptations of this clade, and suggests that Palaeophiidae underwent a major diversification in the Paleocene and early Eocene in response to the extinction of Cretaceous marine reptiles and concurrent global warming.