| 1. |
- Hoshino, Yosuke, et al.
(author)
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Cryogenian evolution of stigmasteroid biosynthesis
- 2017
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In: Science Advances. - : AMER ASSOC ADVANCEMENT SCIENCE. - 2375-2548. ; 3:9
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Journal article (peer-reviewed)abstract
- Sedimentary hydrocarbon remnants of eukaryotic C-26-C-30 sterols can be used to reconstruct early algal evolution. Enhanced C-29 sterol abundances provide algal cellmembranes a density advantage in large temperature fluctuations. Here, we combined a literature review with new analyses to generate a comprehensive inventory of unambiguously syngenetic steranes in Neoproterozoic rocks. Our results show that the capacity for C-29 24ethyl- sterol biosynthesis emerged in the Cryogenian, that is, between 720 and 635 million years ago during the Neoproterozoic Snowball Earth glaciations, which were an evolutionary stimulant, not a bottleneck. This biochemical innovation heralded the rise of green algae to global dominance of marine ecosystems and highlights the environmental drivers for the evolution of sterol biosynthesis. The Cryogenian emergence of C-29 sterol biosynthesis places benchmark for verifying older sterane signatures and sets a new framework for our understanding of early algal evolution.
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| 2. |
- Landing, Ed, et al.
(author)
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Global standard names for the Lowermost Cambrian Series and Stage
- 2007
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In: Episodes. - 0705-3797. ; 30:4, s. 287-289
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Journal article (peer-reviewed)abstract
- The GSSP marking the base of the Cambrian System was ratified by the IUGS in 1992. Ratification of the GSSP point at the base of the Trichophycus pedum Ichnozone in the Fortune Head section, eastern Newfoundland, Canada, automatically defined the conterminant base of the lowermost series and stage of the Cambrian although names for those subdivisions were not proposed at the time of the decision. In 2007, the IUGS ratified the names Terreneuvian Series and Fortunian Stage for these previously unnamed chronostratigraphic subdivisions. The Terreneuvian Series replaces the provisional name "Series 1," and the Fortunian Stage replaces the provisional name "Stage 1," of the Cambrian System.
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| 3. |
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| 4. |
- Moczydlowska-Vidal, Malgorzata, 1951-, et al.
(author)
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Ediacaran algal cysts from the Doushantuo Formation, South China
- 2022
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In: Geological Magazine. - : Cambridge University Press. - 0016-7568 .- 1469-5081. ; 159:7, s. 1050-1070
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Journal article (peer-reviewed)abstract
- Early-middle Ediacaran organic-walled microfossils from the Doushantuo Formation studied in several sections in the Yangtze Gorges area, South China, show ornamented cyst-like vesicles of very high diversity. These microfossils are diagenetically permineralized and observed in petrographic thin-sections of chert nodules. Exquisitely preserved specimens belonging to seven species of Appendisphaera, Mengeosphaera, Tanarium, Urasphaera and Tianzhushania contain either single or multiple spheroidal internal bodies inside the vesicles. These structures indicate reproductive stages, endocyst and dividing cells, respectively, and are preserved at early to late ontogenetic stages in the same taxa. This new evidence supports the algal affiliations for the studied taxa and refutes previous suggestions of Tianzhushania being animal embryo or holozoan. The first record of a late developmental stage of a completely preserved specimen of T. spinosa observed in thin-section demonstrates the interior of vesicles with clusters of identical cells but without any cavity that is diagnostic for recognizing algal cysts vs animal diapause cysts. Various lines of evidence to infer biological affinities of these microfossils - morphology, reproductive characters, spatial arrangement of cells, and biochemical properties of the vesicle wall - are collectively characteristic of algal clades. Recognizing the biological affinities of these microfossils is key to understanding whether animals capable of producing such morphologically complex diapause cysts had an early Ediacaran fossil record (633-610 Ma), or the microfossils were non-animal holozoans or algae as argued herein for Tianzhushania spinosa and other studied microfossils.
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| 5. |
- Moczydlowska-Vidal, Malgorzata, 1951-, et al.
(author)
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Ediacaran metazoan fossils with siliceous skeletons from the Digermulen Peninsula of Arctic Norway
- 2021
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In: Journal of Paleontology. - : Cambridge University Press. - 0022-3360 .- 1937-2337. ; 95:3, s. 440-475
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Journal article (peer-reviewed)abstract
- In this study, a new assemblage of Ediacaran metazoan fossils is reported from the basal Stahpogieddi Formation on the Digermulen Peninsula of Arctic Norway, including Anulitubus n. gen. Moczydlowska in Moczydlowska et al., Anulitubus formosus n. gen. n. sp. Moczydlowska in Moczydlowska et al., Coniculus n. gen. Moczydlowska in Moczydlowska et al., Coniculus elegantis n. gen. n. sp. Moczydlowska in Moczydlowska et al., Fistula n. gen. Moczydlowska in Moczydlowska et al., and Fistula crenulata n. gen. n. sp. Moczydlowska in Moczydlowska et al. The specimens are three-dimensionally preserved and include tubular and conical skeletons that are morphologically distinguished by their body-wall constructions, radial symmetry, polarity, segmentation, and annulation. The skeletons are interpreted to be biomineralized by primary silica based on computed micro-tomographic, petrographic, geochemical, and spectroscopic evidence of originally rigid body wall with layers of constant thicknesses, composed of opal, microcrystalline quartz, and an admixture of carbonaceous material, which differ from the host sediment mineralogy and do not show replacement or encrustation. The fossil-bearing interval immediately overlies strata of Gaskiers age and can be bracketed within 580-541 Ma, but it is estimated to be ca. 575 Ma on the basis of averaged sedimentation rates and biostratigraphic correlations with Ediacaran biota found in up-section deposits of ca. 558-555 Ma. Future new findings of such fossils in different preservation modes and further multi-collector inductively coupled plasma mass spectrometry, which shows the silicon fractionation and traces its biogenic origin versus inorganic mineralization, may corroborate the interpretation of biogenic silicification of these earliest skeletal fossils.
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| 6. |
- Moczydlowska-Vidal, Malgorzata, 1951-, et al.
(author)
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Ediacaran radiation of organic-walled microbiota recorded in the Ura Formation, Patom Uplift, East Siberia
- 2012
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In: Precambrian Research. - Elsevier : Elsevier BV. - 0301-9268 .- 1872-7433. ; 198, s. 1-24
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Journal article (peer-reviewed)abstract
- A new assemblage of morphologically complex, ornamented and large organic-walled microfossils (acritarchs) from the Ura Formation in the Patom Uplift, East Siberia, is identified and taxonomically described as a continuation of the previous studies (0245 and 0305). Nine new species and three new genera are recognised; 10 other species are known from occurrences in the Ediacaran strata of Australia, China, the Siberian Platform (SP), and the East European Platform (EEP). The new species are morphologically advanced phenotypes, showing innovative elements of vesicle ornamentation and variable symmetry, and internal bodies within zygotic cyst-like vesicles that are indicative of the sexual reproduction stage of the microorganism. The morphological features and the preliminarily recognised cell wall ultrastructure are characteristic of phytoplankton; thus the described microfossils are identified as green microalgae. The relative age of the Ura assemblage, by comparison to microfossil records elsewhere and estimated in the regional geologic context of the Dalniaya Taiga (containing the Ura Formation) and the Zhuya (overlying) groups, is suggested to be early Ediacaran. Radiation of the Ura-type microorganisms pre-dates the records of Ediacaran microbiota from Australia (the Pertatataka association/Ediacaran Complex Acanthomorphic Palynoflora), the Siberian Platform (Khamaka-type assemblages), and the EEP (Vychegda association) but is preceded by the appearance of certain species recorded in China at the base of the Doushantuo Formation. The stratigraphic ranges of genera co-occurring in these palaeocontinents (Appendisphaera, Cavaspina, Ceratosphaeridium, Gyalosphaeridium,Labruscasphaeridium, Multifronsphaeridium, Tanarium, and Variomargosphaeridium) are extended by their lower record in the Patom Uplift and may span a major portion of the Ediacaran Period. The refined stratigraphic distribution of microfossils may provide a means for zoning the entire Ediacaran System in addition to the upper zones established in Australia.
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| 7. |
- Moczydlowska-Vidal, Malgorzata, 1951-
(author)
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Life cycle of early Cambrian microalgae from the Skiagia-plexus acritarchs
- 2010
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In: Journal of Paleontology. - 0022-3360 .- 1937-2337. ; 84:2, s. 216-230
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Journal article (peer-reviewed)abstract
- Light microscopy studies on new materials and museum collections of early Cambrian organic-walled microfossils, informally called acritarchs, provide the observations on phenetic features that permit a comparison to certain Modern microalgae and the recognition of various developmental stages in their life cycle. The microfossils derive from various depositional settings in Estonia, Australia, Greenland, Sweden and Poland. The exceptionally preserved microfossils reveal the internal body within the vesicle, - the endocyst -, and the process of releasing the endocyst from the cyst. Vegetative cells, cysts and endocysts are distinguished, and the hypothetical reconstruction of a complex life cycle with the alternation of sexual and asexual generations is proposed. Acritarchs from the Skiagia-plexus are cysts, and likely zygotes in the sexual generation, which periodically rested as “benthic plankton”. Some microfossils of the Leiosphaeridia-plexus are inferred to be vegetative cells, were planktonic and probably haplobiontic. These form-taxa may belong to a single biological species, or a few closely related species, and represent the developmental stages and alternating generations in a complex life cycle that are expressed by polymorphic, sphaero- and acanthomorphic acritarchs. The morphological resemblance and diagnostic cell walls ultrastructure with the trilaminar sheath structure known from earlier studies suggest that the early Cambrian microfossils are the ancestral representatives and/or early lineages to Modern Class Chlorophyceae, and the orders Volvocales and Chlorococcales.
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| 8. |
- Moczydlowska-Vidal, Malgorzata, et al.
(author)
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Life cycle of Early Ordovician acritarch species
- 2003
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Conference paper (pop. science, debate, etc.)abstract
- Acritarchs are marine planktonic autotrophic protistans of heterogeneous origins. Their diversification into many morphotypes occurred throughout Neoproterozic and Early Palaeozoic; some morphotypes represent green algal classes but most are of unknown biological affinities. Palaeobiology and relationships to extant microbiota of some acritarchs, with emphasis on their life cycle, reproduction and environmental adaptations, may be inferred from phonetic morphological features and cell wall ultrastucture. Microfossils from the Cambrian-Ordovician of China are studied to reveal the wall ultrastructure of vegetative cells and dormant/reproductive cysts, the structural complexity of early eukaryotic cytoskeleton, and to recognize by morphological and ultrastructural means the relationships between various phenotypes. Acritarchs are considered to be preservable cysts of unicellular algae. The new discovery of the entire organism consisting of vegetative envelope and internal cyst shows that some taxa indeed represent the dormant/reproductive cysts whereas other may represent vegetative cells in their complex life cycle. Formation of the cyst, the excystment structure (pylome) and change of the generations (sexual and asexual) in the life cycle of unicellular microbiota may shed light on the development of the early adaptations to survive ecological crises events and as a competitive advantage in increasingly complex marine ecosystems.
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| 9. |
- Moczydlowska-Vidal, Malgorzata, 1951-, et al.
(author)
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Micro- and nano-scale ultrastructure of cell walls in Cryogenian microfossils : revealing their biological affinity
- 2010
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In: Lethaia. - : Scandinavian University Press / Universitetsforlaget AS. - 0024-1164 .- 1502-3931. ; 43:2, s. 129-136
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Journal article (peer-reviewed)abstract
- Recently established protocols and methods in advanced microscopy and spectrometry applied to studies of ancient unicellular organic-walled microfossils of uncertain biological affinities (acritarchs) provide new evidence of the fine ultrastructure of cell walls and their biochemistry that support the interpretation of some such microfossils as photosynthesizing microalgae. The micro-scale and nanoscale ultrastructure of the cell walls of late Cryogenian sphaeromorphic acritarchs from the Chichkan Formation (Kazakhstan) revealed by the advanced techniques and studied originally by Kempe et al. (2005) is here further analyzed and compared to that of modern microalgal analogues. On the basis of such comparison, we interpret the preserved cell wall ultrastructure to reflect original layering and lamination within sublayers of the fossil wall, rather than being a result of taphonomic and diagenetic alteration. The outer thick layer represents the primary wall and the inner layer the secondary wall of the cell, whereas the laminated amorphous sub-layers, 10-20 nm in thickness and revealed by transmission electron and atomic force microscopy, are recognized as trilaminar sheath structure (TLS). Because two-layered cell walls, trilaminar sheaths, and the position of the TLS within the fossil cell wall are characteristic of the mature developmental state in cyst morphogenesis in modern microalgae, we infer that the Chichkan sphaeromorphs are likely resting cells (aplanospores) of chlorophyceaen green microalgae from the Order Volvocales.
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| 10. |
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