Mistaken Point Research Articles

Ediacaran marine animal forests and the ventilation of the oceans

The rise of animals across the Ediacaran-Cambrian transition marked a step-change in the history of life, from a microbially dominated world to the complex macroscopic biosphere we see today.1,2,3 While the importance of bioturbation and swimming in altering the structure and function of Earth systems is well established,4,5,6 the influence of epifaunal animals on the hydrodynamics of marine environments is not well understood. Of particular interest are the oldest "marine animal forests,"7 which comprise a diversity of sessile soft-bodied organisms dominated by the fractally branching rangeomorphs.8,9 Typified by fossil assemblages from the Ediacaran of Mistaken Point, Newfoundland,8,10,11 these ancient communities might have played a pivotal role in structuring marine environments, similar to modern ecosystems,7,12,13 but our understanding of how they impacted fluid flow in the water column is limited. Here, we use ecological modeling and computational flow simulations to explore how Ediacaran marine animal forests influenced their surrounding environment. Our results reveal how organism morphology and community structure and composition combined to impact vertical mixing of the surrounding water. We find that Mistaken Point communities were capable of generating high-mixing conditions, thereby likely promoting gas and nutrient transport within the "canopy." This mixing could have served to enhance local-scale oxygen concentrations and redistribute resources like dissolved organic carbon. Our work suggests that Ediacaran marine animal forests may have contributed to the ventilation of the oceans over 560 million years ago, well before the Cambrian explosion of animals.

Frond orientations with independent current indicators demonstrate the reclining rheotropic mode of life of several Ediacaran rangeomorph taxa

AbstractFossils from the deep-sea Ediacaran biotas of Newfoundland are among the oldest architecturally complex soft-bodied macroorganisms on Earth. Most organisms in the Mistaken Point–type biotas of Avalonia—particularly the fractal-branching frondose Rangeomorpha— have been traditionally interpreted as living erect within the water column during life. However, due to the scarcity of documented physical sedimentological proxies associated with fossiliferous beds, Ediacaran paleocurrents have been inferred in some instances from the preferential orientation of fronds. This calls into question the relationship between frond orientation and paleocurrents. In this study, we present an integrated approach from a newly described fossiliferous surface (the “Melrose Surface” in the Fermeuse Formation at Melrose, on the southern portion of the Catalina Dome in the Discovery UNESCO Global Geopark) combining: (1) physical sedimentological evidence for paleocurrent direction in the form of climbing ripple cross-lamination and (2) a series of statistical analyses based on modified polythetic and monothetic clustering techniques reflecting the circular nature of the recorded orientation of Fractofusus misrai specimens. This study demonstrates the reclining rheotropic mode of life of the Ediacaran rangeomorph taxon Fractofusus misrai and presents preliminary inferences suggesting a similar mode of life for Bradgatia sp. and Pectinifrons abyssalis based on qualitative evidence. These results advocate for the consideration of an alternative conceptual hypothesis for position of life of Ediacaran organisms in which they are interpreted as having lived reclined on the seafloor, in the position that they are preserved.

The rangeomorph Pectinifrons abyssalis: Hydrodynamic function at the dawn of animal life

Rangeomorphs are among the oldest putative eumetazoans known from the fossil record. Establishing how they fed is thus key to understanding the structure and function of the earliest animal ecosystems. Here, we use computational fluid dynamics to test hypothesized feeding modes for the fence-like rangeomorph Pectinifrons abyssalis, comparing this to the morphologically similar extant carnivorous sponge Chondrocladia lyra. Our results reveal complex patterns of flow around P.abyssalis unlike those previously reconstructed for any other Ediacaran taxon. Comparisons with C. lyra reveal substantial differences between the two organisms, suggesting they converged on a similar fence-like morphology for different functions. We argue that the flow patterns recovered for P.abyssalis do not support either a suspension feeding or osmotrophic feeding habit. Instead, our results indicate that rangeomorph fronds may represent organs adapted for gas exchange. If correct, this interpretation could require a dramatic reinterpretation of the oldest macroscopic animals.

Morphological variation in the rangeomorph organism Fractofusus misrai from the Ediacaran of Newfoundland, Canada

AbstractThe Ediacaran rangeomorph Fractofusus misrai is the most common and best-preserved of the E Surface fossil assemblage in the Mistaken Point Ecological Reserve of southeastern Newfoundland, Canada. Fractofusus has been interpreted as a fusiform epifaunal soft-sediment recliner, and like other rangeomorphs it has a self-similar, fractal-like branching morphology. The rangeomorph branching of Fractofusus has been considered to be identical on the upper and lower surfaces; however, study of specimens with complex biostratinomic histories suggests clear differences between the upper and lower surfaces. The first-order branches grew downwards into the sediment from a high point near the midline but grew above the sediment–water interface at their lateral and distal margins. Our new three-dimensional appreciation of rangeomorph branching in Fractofusus explains many of the taphomorphs of Fractofusus including straight, curved, kinked and tousled forms. The three-dimensional morphology, mode of life, taphonomy and palaeoenvironmental interactions of F. misrai are discussed along with a new three-dimensional reconstruction.

Rheotropic Epifaunal Growth, Not Felling by Density Currents, Is Responsible for Many Ediacaran Fossil Orientations at Mistaken Point

OPINION article Front. Earth Sci., 14 February 2022 | https://doi.org/10.3389/feart.2022.849194

The sponge pump as a morphological character in the fossil record

AbstractThe timing of early animal evolution remains one of the biggest conundrums in biology. Molecular data suggest Porifera diverged from the metazoan lineage some 800 Ma to 650 Ma, which contrasts with the earliest widely accepted fossils of sponges at 535 Ma. However, the lack of criteria by which to recognize the earliest animals in the fossil record presents a challenge. The sponge body plan is unchanged since the early Cambrian, which makes a sponge-type animal a good candidate for the earliest fossils. Here we propose a method for identifying an organism as sponge grade by translating the sponge pump character into a quantifiable morphological trait. We show that the ratio between the two major components of the aquiferous system, the cross-sectional area of the osculum (OSA) and the surface area of the whole sponge (SA), is an effective metric of the pump character of extant sponges and that the slope of this ratio is distinct for three classes of Porifera: Demospongiae, Calcarea, and Hexactinellida. Furthermore, this metric is effective at distinguishing as sponges both extant taxa and fossils from two extremes of the Phanerozoic, the Cambrian and Paleogene. We tested this metric on the putative Ediacaran spongeThectardis avalonensisfrom Mistaken Point, Newfoundland, and foundThectardisfits both with Cambrian sponges and with modern demosponges. These analyses show that the OSA/SA ratio is a reliable character by which to identify fossils as sponge grade, opening up exciting possibilities for classifying new fossils as sponges.

Orientations of Mistaken Point Fronds Indicate Morphology Impacted Ability to Survive Turbulence

The Ediacaran fossils of the Mistaken Point E surface have provided crucial insight into early animal communities, including how they reproduced, the importance of Ediacaran height and what the most important factors were to their community dynamics. Here, we use this iconic community to investigate how morphological variation between eight taxa affected their ability to withstand different flow conditions. For each of Beothukis, Bradgatia, Charniodiscus procerus, Charniodiscus spinosus, Plumeropriscum, Primocandelabrum, Thectardis and Fractofusus we measured the orientation and length of their stems (if present) and their fronds. We statistically tested each taxon’s stem and frond orientation distributions to see whether they displayed a uniform or multimodal distribution. Where multimodal distributions were identified, the stem/frond length of each cohort was tested to identify if there were differences in size between different orientation groups. We find that Bradgatia and Thectardis show a bimodal felling direction, and infer that they were felled by the turbulent head of the felling flow. In contrast, the frondose rangeomorphs including Beothukis, Plumeropriscum, Primocandelabrum, and the arboreomorphs were felled in a single direction, indicating that they were upright in the water column, and were likely felled by the laminar tail of the felling flow. These differences in directionality suggests that an elongate habit, and particularly possession of a stem, lent greater resilience to frondose taxa against turbulent flows, suggesting that such taxa would have had improved survivability in conditions with higher background turbulence than taxa like Bradgatia and Thectardis, that lacked a stem and had a higher centre of mass, which may have fared better in quieter water conditions.

A re-assessment of the taxonomy, palaeobiology and taphonomy of the rangeomorph organism Hapsidophyllas flexibilis from the Ediacaran of Newfoundland, Canada

Newfoundland’s Mistaken Point is home to some of the world’s oldest known complex body fossils. Detailed observation of newly discovered specimens has led to a reconsideration of Hapsidophyllas flexibilis, which is diagnosed as being a complex epifaunal multifoliate rangeomorph with a basal stolon. This study has revealed that published material of H. flexibilis includes a cryptic epifaunal recliner that grew on, and slightly into, the seafloor in a manner similar to the common Ediacaran epifaunal organisms Fractofusus and Beothukis. The new genus and species erected herein to accommodate these epifaunal organisms is Gigarimaneta samsoni, an organism that is broadly round in outline and composed of rows of allantoid units that are further sub-divided into smaller spherocylindrical units. There is no evidence of rangeomorph branching, instead the divisions seen in Gigarimaneta are considered to represent invaginations of the lower epithelium that increased the surface-area-to-volume ratio of these organisms without the creation of true branches. The resulting ‘pneu’-like divisions may have allowed this quasi-infaunal taxon to have gained nutriment from the substrate via the culturing of sulfur-oxidizing bacteria, either as endo- or epi-symbionts, perhaps coupled with the absorption of dissolved organic material from pore/seawater.

Palaeobiology of the reclining rangeomorph Beothukis from the Ediacaran Mistaken Point Formation of southeastern Newfoundland

AbstractBeothukis mistakensis from the Ediacaran System of Newfoundland, Canada demonstrates complex fractal-like morphology through the development of primary-, secondary- and tertiary-order Rangea-like units. The primary-order rangeomorph units observed in B. mistakensis are tightly juxtaposed, show no evidence of being independent of one another and are made up of chamber-like secondary-order – probably mesoglea-filled – units. The growth of these rangeomorph units demonstrates that the frond developed from the tip towards the basal region through ontogeny. The tertiary-order units of Beothukis are considered to represent surface morphology on the secondary-order units. This is in contrast to palaeobiological reconstructions of Beothukis that invoke three-dimensional fractal-like branches with independent units, which has been used to infer an osmotrophic mode of life. It is considered here that the fractal-like morphology of the lower surface of B. mistakensis was an adaptation to increase surface area to volume ratio. The quilted morphology of Beothukis proposed here is consistent with a sessile, reclining, phagocytotic and/or chemosymbiotic mode of life similar to that invoked for the reclining rangeomorph Fractofusus.

Spatial analyses of Ediacaran communities at Mistaken Point – ADDENDUM

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A Chronostratigraphic Framework for the Rise of the Ediacaran Macrobiota: New Constraints from Mistaken Point Ecological Reserve, Newfoundland

Abstract The Conception and St. John’s Groups of southeastern Newfoundland contain some of the oldest known fossils of the Ediacaran macrobiota. The Mistaken Point Ecological Reserve UNESCO World Heritage Site is an internationally recognized locality for such fossils and hosts early evidence for both total group metazoan body fossils and metazoan-style locomotion. The Mistaken Point Ecological Reserve sedimentary succession includes ∼1500 m of fossil-bearing strata containing numerous dateable volcanogenic horizons, and therefore offers a crucial window into the rise and diversification of early animals. Here we present six stratigraphically coherent radioisotopic ages derived from zircons from volcanic tuffites of the Conception and St. John’s Groups at Mistaken Point Ecological Reserve. The oldest architecturally complex macrofossils, from the upper Drook Formation, have an age of 574.17 ± 0.66 Ma (including tracer calibration and decay constant uncertainties). The youngest rangeomorph fossils from Mistaken Point Ecological Reserve, in the Fermeuse Formation, have a maximum age of 564.13 ± 0.65 Ma. Fossils of the famous “E” Surface are confirmed to be 565.00 ± 0.64 Ma, while exceptionally preserved specimens on the “Brasier” Surface in the Briscal Formation are dated at 567.63 ± 0.66 Ma. We use our new ages to construct an age-depth model for the sedimentary succession, constrain sedimentary accumulation rates, and convert stratigraphic fossil ranges into the time domain to facilitate integration with time-calibrated data from other successions. Combining this age model with compiled stratigraphic ranges for all named macrofossils within the Mistaken Point Ecological Reserve succession, spanning 76 discrete fossil-bearing horizons, enables recognition and interrogation of potential evolutionary signals. Peak taxonomic diversity is recognized within the Mistaken Point and Trepassey Formations, and uniterminal rangeomorphs with undisplayed branching architecture appear several million years before multiterminal, displayed forms. Together, our combined stratigraphic, paleontological, and geochronological approach offers a holistic, time-calibrated record of evolution during the mid–late Ediacaran Period and a framework within which to consider other geochemical, environmental, and evolutionary data sets.

Reevaluación crítica del holotipo de <em>Beothukis mistakensis</em>, único organismo rangeomorfo excepcionalmente preservado en Mistaken Point, Terranova, Canadá

El holotipo de Beothukis mistakensis en Mistaken Point, Terranova, es el único ejemplar actualmente conocido que puede ser colocado definitivamente dentro de la especie. Las diferencias morfológicas entre el holotipo de B. mistakensis y la especie plumosa sugieren que ambas no son congéneres y que Culmofrons plumosa debería conservarse como un taxón válido tal como se estableció originalmente.

On the Adhesion of Sediment to Footwear and the Implications for Geoconservation

The fossils at the Mistaken Point UNESCO World Heritage Site represent evidence of the oldest known, large, architecturally complex, life on Earth and are protected by the Government of Newfoundland and Labrador as part of an Ecological Reserve. Following concerns that foot traffic across the fossil surfaces was having a deleterious effect on the geoheritage, visitors were made to wear quilted ‘Bama Sokkets’ starting in 2009—though the efficacy of this management technique has never been tested. Previous studies in the materials sciences have revealed that footwear erosion of rock surfaces is primarily caused by the action of sediment between the foot and the surface; however, these findings have not before been applied to geoconservation research. In this study, we examine the adhesion of sediment to several footwear types. Our experiments reveal that under wet conditions, the ‘Bama Sokkets’ perform poorly in repelling sediment, and as such their use as a geoconservation management tool is discouraged. This study recommends the use of hydrophobic footwear for walking on geoheritage rock surfaces and has led to policy change at the Mistaken Point UNESCO World Heritage Site.

The utility of height for the Ediacaran organisms of Mistaken Point.

Ediacaran fossil communities consist of the oldest macroscopic eukaryotic organisms. Increased size (height) is hypothesized to be driven by competition for water column resources, leading to vertical/epifaunal tiering and morphological innovations such as stems. Using spatial analyses, we find no correlation between tiering and resource competition, and that stemmed organisms are not tiered. Instead, we find that height is correlated with greater offspring dispersal, demonstrating the importance of colonization potential over resource competition.

Registration of infrared and visible light image based on visual saliency and scale invariant feature transform

Visual saliency is a type of visual feature which simulates visual attention selection mechanism in biological system and has better robustness and invariance. A rapid infrared image and visible light image registration method based on visual saliency and SIFT (scale invariant feature transform) is proposed in this paper. The method adopts amplitude modulation Fourier transform to construct saliency map, and the image salient points are achieved preliminarily by salient threshold. Subsequently, this method calculates the local entropy for these salient points because of entropy’s character for information measurement, then these points are reordered and screened based on the strategy of entropy priority. The screened results are thought as centers for salient regions. Morphological operation is used for growing and merging for neighbor salient scene region in image. Aiming at the abstracted salient region for image, PCA (principal component analysis)-SIFT algorithm is proposed, which can produce the compressed SIFT registration features and largely reduce the computational cost of image registration. The proposed algorithm adopts random sampling conformance method to remove the mistaken point pairs before calculating the model parameter of affine transformation for registration between infrared image and visible lights. The experimental results indicate that the method has good invariance under image scale, rotation, translation, and illumination variation and can realize effective registration between infrared image and visible lights. Compared with some classical algorithms, the proposed method has advantage in registration accuracy and registration speed obviously.

The Ediacaran fossils of Charnwood Forest: Shining new light on a major biological revolution

Charnwood Forest (UK) hosts some of the oldest and best-preserved macrofossils known from the Ediacaran. It is the counterpoint to the more widely studied fossil sites of south-eastern Newfoundland (Canada), which include the recently-designated UNESCO World Heritage Site of Mistaken Point. Discoveries made in Charnwood Forest since 2008 have the potential to revolutionise our understanding of the evolution of complex macroscopic life and the subsequent development of ‘modern’ (i.e. Phanerozoic) ecosystems. The sites in Charnwood include the holotypes for several iconic Ediacaran taxa, and potentially both the oldest and youngest representatives of the deep-water Avalon Assemblage. These communities provide a unique opportunity to test models of community ecology, biological endemism and environmental sensitivity and adaptability in the Ediacaran. Here, we review the geology of Charnwood Forest and the palaeobiology of its biotas, and we summarise recent scientific advances in the context of our developing understanding of early macroscopic life. We review the application of Reflectance Transformation Imaging to these ancient communities, and signpost exciting new directions for research in Charnwood Forest, almost 170 years after the fossils were first brought to light.

Spatial analyses of Ediacaran communities at Mistaken Point

AbstractBedding-plane assemblages of Ediacaran fossils from Mistaken Point, Newfoundland, are among the oldest known records of complex multicellular life on Earth (dated to ~565 Ma). The in situ preservation of these sessile but otherwise deeply enigmatic organisms means that statistical analyses of specimen positions can be used to illuminate their underlying ecological dynamics, including the interactions between taxa.Fossil assemblages on Mistaken Point D and E surfaces were mapped to millimeter accuracy using differentiated GPS. Spatial correlations between 10 well-defined taxa (Bradgatia, Charniid,Charniodiscus,Fractofusus, Ivesheadiomorphs, Lobate Discs,Pectinifrons,Plumeropriscum,Hiemalora, andThectardis) were identified using Bayesian network inference (BNI), and then described and analyzed using spatial point-process analysis. BNI found that the E-surface community had a complex web of interactions and associations between taxa, with all but one taxon (Thectardis) interacting with at least one other. The unique spatial distribution ofThectardissupports previous, morphology-based arguments for its fundamentally distinct nature. BNI revealed that the D-surface community showed no interspecific interactions or associations, a pattern consistent with a homogeneous environment.On the E surface, all six of the abundant taxonomic groups (Fractofusus,Bradgatia, Charniid,Charniodiscus,Thectardis, andPlumeropriscum) were found to have a unique set of interactions with other taxa, reflecting a broad range of underlying ecological responses. Four instances of habitat associations were detected between taxa, of which two (Charniodiscus–PlumeropriscumandPlumeropriscum–Fractofusus) led to weak competition for resources. One case of preemptive competition between Charniid and Lobate Discs was detected. There were no instances of interspecific facilitation. Ivesheadiomorph interactions mirror those ofFractofususandCharniodiscus, identifying them as a form-taxonomic grouping of degradationally homogenized taphomorphs. The absence of increased fossil abundance in proximity to these taphomorphs argues against scavenging or saprophytic behaviors dominating the E-surface community.

Great Canadian Lagerstätten 6. Mistaken Point Ecological Reserve, Southeast Newfoundland

Mistaken Point Ecological Reserve (MPER) World Heritage Site, on the southeastern coast of Newfoundland, Canada, is one of the foremost global Ediacaran fossil localities. MPER contains some of the oldest known assemblages of the soft-bodied Ediacaran macrobiota, and its fossils have contributed significantly to Ediacaran paleobiological research since their initial discovery in 1967. Preservation of multiple in situ benthic paleocommunities, some comprising thousands of specimens, has enabled research into Ediacaran paleoecology, ontogeny, taphonomy, taxonomy and morphology, offering insights into the possible phylogenetic positions of Ediacaran taxa within the tree of life. Meanwhile, a thick and continuous geological record enables the fossils to be placed within a well-resolved temporal and paleoenvironmental context spanning an interval of at least 10 million years. This article reviews the history of paleontological research at MPER, and highlights key discoveries that have shaped global thinking on the Ediacaran macrobiota.RÉSUMÉLe site du Patrimoine mondial de la Réserve écologique de Mistaken Point (MPER), sur la côte sud-est de Terre-Neuve, au Canada, est l'une des principales localités fossilifères édiacariennes de la planète. Le MPER renferme quelques-uns des plus anciens assemblages connus de macrobiote édicarien à parties molles, et ses fossiles ont contribué de manière significative à la recherche paléobiologique édiacarienne depuis leur découverte en 1967. La préservation de multiples paléocommunautés benthiques in situ, dont certaines comptant des milliers de spécimens, a permis de faire des recherches en paléoécologie, ontogenèse, taphonomie, taxonomie et morphologie de biotes édiacariens, ce qui a permis d’avoir un aperçu de différentes positions phylogénétiques possibles des taxons édiacariens dans l'arborescence biologique. Aussi, grâce à une colonne géologique épaisse et continue, on a pu placer ces fossiles dans un contexte temporel et paléoenvironnemental bien circonscrit qui s’étend sur un intervalle d'au moins 10 millions d'années. Cet article passe en revue l'histoire de la recherche paléontologique au MPER et souligne les découvertes majeures qui ont façonné la réflexion sur le macrobiote édiacarien.

Post-fossilization processes and their implications for understanding Ediacaran macrofossil assemblages

Abstract Fossil assemblages from Newfoundland's Avalon Peninsula preserve diverse examples of the enigmatic Ediacaran macrobiota, offering some of the earliest evidence for large and complex multicellular life. These fossils are exposed on extensive coastal bedding planes in extraordinary abundances, permitting palaeoecological studies based on census data from spatially extensive palaeocommunities. Such studies have been used to constrain the reproductive strategy and phylogenetic placement of Ediacaran organisms. Geological mapping and stratigraphic correlation in the Mistaken Point Ecological Reserve reveal that some fossil-bearing surfaces can be tracked over distances of several kilometres. These laterally extensive surfaces reveal that the modern processes by which the sediment overlying a fossil surface is removed may impose important controls on the observed composition of fossil assemblages. Weathering and erosion – along with factors associated with tectonics, metamorphism and discovery – are here grouped as ‘post-fossilization processes’ and introduce biases that are often not explicitly accounted for in palaeoecological studies. Specifically, post-fossilization processes may differentially influence the preservational fidelity of individual specimens on a given surface and generate features that could be mistaken for original morphological characters. We therefore recommend that post-fossilization processes must be considered when undertaking palaeoecological studies in Ediacaran successions in Newfoundland and, potentially, elsewhere.

Ediacaran fossils in thin-section

Retallack, G.J., June 2016. Ediacaran fossils in thin-section. Alcheringa 40, xx–xx. ISSN 0311-5518Megafossils from the Ediacaran Period (635–541 Ma) have been controversial in part because many are mere impressions in coarse-grained rocks. New examination of these fossils in petrographic thin-sections reveals various features that inform understanding of the biological affinities of these problematic fossils. Material examined includes Dickinsonia costata from the Ediacara Member of the Rawnsley Quartzite in South Australia, Ernietta plateauensis from the Kliphoek Member of Namibia, Ivesheadia lobata from the Drook Formation of Newfoundland, Charnia antecedens and Charniodiscus spinosus from the Mistaken Point Formation of Newfoundland, Aspidella terranovica from the Fermeuse Formation of Newfoundland, and Nemiana simplex from the Mogilev Formation of Ukraine and the Verkovka Formation of Russia. Three characteristics stand out for all but Nemiana. First, these fossils were remarkably resistant to burial compaction, as originally inferred from depth gauge measurements of overlying moulds, and here confirmed by thin-sections perpendicular to bedding planes. Second, thin-sections reveal a construction of micrometric branching elongate structures forming millimetric hollow elongate structures in fractal arrangements. Third, some of the fossils are asymmetric bifacial or unifacial, with a thick finished upper wall but lower wall thin or non-existent and attached to elongate structures downward into sediment. Compaction-resistant fossils with asymmetric histological layering are most like crustose and fruticose lichens fortified with chitin. In contrast, non-resistant impressions in the tops of beds filled by overlying cross-bedded sediment, as in Nemiana, preserve no informative histology and are similar to lake balls and microbial colonies.Gregory J. Retallack [gregr@uoregon.edu], Department of Geological Sciences, University of Oregon, Eugene, OR 97403-1272, USA.