Beothukis 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.
The palaeopascichnids are a relatively abundant component of the Ediacara biota. The eponymous Palaeopascichnus delicatus consists of serially arranged, millimetre-scale allantoid chambers that have variously been interpreted as evidence of movement, feeding traces, and body fossils of various affinities. Palaeopascichnus has most recently been compared to the deep-marine Xenophyophora, an extant group of large, benthic protists characterized by their greater size and possession of stercomata within their cells. The morphometric variation in palaeopascichnids is assessed using material from the Avalon Peninsula of Newfoundland, Canada. The application of quantitative morphological analysis to the study of over 90 well-preserved specimens of Palaeopascichnus demonstrates considerable variation in chamber shape and size, and in behaviour along the chamber series. The combination of morphometric and multivariate statistical analysis allows the recognition of natural groups within the dataset, thereby demonstrating variability within and between morphospecies. Morphological comparisons of fossil palaeopascichnids with fossil and extant protistan taxa support the proposed protistan affinity of Palaeopascichnus, allowing further resolution regarding the diversity and disparity within this prominent element of the later Ediacara biotas of Gondwana and Baltica.
The Avalon assemblage of Newfoundland, Canada contains abundant fossils of enigmatic soft-bodied Ediacaran organisms, many with remarkable preservation. One of the most numerically dominant groups of organisms in the assemblage is the Rangeomorpha, a frondose clade characterized by self-similar, repeating branching architecture known worldwide from rocks of Ediacaran age. Variations in branching characters and gross morphology have historically been used to divide this group, but there has been little consistency in taxonomic approach to the Rangeomorpha, concomitantly there are conflicting opinions that have resulted in some overlapping taxonomic diagnoses. Here we investigate one such taxonomic dispute, the Beothukis/Culmofrons problem. The two genera were recently synonymized into Beothukis based on the assertion that some characters were of different taxonomic rank than others. Subsequent debate has focused on which taxonomic characters displayed by the Rangeomorpha should be used for genus- and species-level subdivision. To test the validity of using continuous versus discrete characters in rangeomorph taxonomy we use a combination of morphometrics and statistical analysis to identify natural clusters within our specimen dataset which was collected from Beothukis sensu lato including material that was, until recently, attributed to Culmofrons. The results of the cluster assignment validates the differentiation between Beothukis mistakensis and Beothukis (Culmofrons) plumosa, but cannot—in isolation—be used to determine at what taxonomic rank that distinction should be made. We demonstrate a considerable degree of variation within Beothukis and Culmofrons, which has not yet been recorded for unifoliate rangeomorph taxa.
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.
The Winterhouse Formation (Port au Port Peninsula, western Newfoundland, Canada) is a lateral equivalent to the Utica and Macasty formations farther west. With hydrocarbon stains and odours as a guide towards a common and regional upper Ordovician hydrocarbon system, Winterhouse rocks may yet contain their own suite of source reservoir and seal strata, with coarser, sandier beds perhaps playing host to other varieties of conventional and unconventional hydrocarbon traps. Hence, addressing basic properties of fluid transmission is an important and unknown variable that needs to be addressed for this formation. In this pilot study, Mercury Intrusion Porosimetry (MIP) is applied to measure the petrophysical properties of a single tight (low porosity, low permeability) quartz-carbonate sandstone sample from a Winterhouse outcrop. As a tool, Mercury Intrusion Porosimetry is strongly dependent on conformity of sample size and shape as a determinant of pore accessibility. Hence two sample types (i) plugs and (ii) cuttings (both real and artificial) are analyzed to explore aspects of core and cuttings preparation and data reduction work flow measurements of storage and transport properties. For artificial "cuttings" a horizontal 2.5 cm core plug and rock fragments are crushed and sieved to replicate fine and coarse fractions. For porosimetry, a Micromeretrics AutoPore IV porosimeter with a maximum pressure of 33,000 psi is used to determine the porosity, pore size distribution, surface area, and bulk density of all samples. Additionally, the FEI Quanta 650 Field Emission Gun (FEG) SEM is used to take images of the pore structure. Mineralogy is determined from the GXMAP measurement mode within FEI Mineral Liberation AnalyzerTM software. A comprehensive analysis corroborating results from MIP and SEM indicates that for these tight rocks, and namely, outcrop plugs, artificial cuttings, and real drill cuttings from a nearby well, all show a similar spectrum of results, but smaller coarse fragments are recommended for reliability. In terms of the Winterhouse strata, it is clear that some of this rock is very tight and highly cemented, but that it also possesses fractures and high permeability values which may make it a good unconventional reservoir. These porosity-permeability results are simply a beginning in a search to understand the petrophysical properties of the strata on the western coast of Newfoundland. The western part of Newfoundland has seen extensive oil exploration efforts in the last few decades, these efforts have resulted in little success. A large degree of this is due to the complex geological history and overall lack of knowledge concerning the structure and diagenesis of these rocks (Cooper et al, 2001). This study will support the new sampling programs in the hope of gaining new insights into potential oil exploitation.
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