Artículos de revistas: "Experimental fossilization"

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Grimes, Stephen T., Fiona Brock, David Rickard, Kevin L. Davies, Dianne Edwards, Derek E. G. Briggs y R. John Parkes. "Understanding fossilization: Experimental pyritization of plants". Geology 29, n.º 2 (2001): 123. http://dx.doi.org/10.1130/0091-7613(2001)029<0123:ufepop>2.0.co;2.

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Carpenter, Kenneth. "Experimental investigation of the role of bacteria in bone fossilization". Neues Jahrbuch für Geologie und Paläontologie - Monatshefte 2005, n.º 2 (17 de febrero de 2005): 83–94. http://dx.doi.org/10.1127/njgpm/2005/2005/83.

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3

Babcock, Loren Edward. "Experimental Investigation of the Processes of Fossilization". Journal of Geoscience Education 46, n.º 3 (mayo de 1998): 252–60. http://dx.doi.org/10.5408/1089-9995-46.3.252.

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4

Hippler, D., N. Hu, M. Steiner, G. Scholtz y G. Franz. "Experimental mineralization of crustacean eggs: new implications for the fossilization of Precambrian–Cambrian embryos". Biogeosciences 9, n.º 5 (21 de mayo de 2012): 1765–75. http://dx.doi.org/10.5194/bg-9-1765-2012.

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Abstract. Phosphatized globular microfossils from the Ediacaran and lower Cambrian of South China represent an impressive record of early animal evolution and development. However, their phylogenetic affinity is strongly debated. Understanding key processes and conditions that cause exceptional egg and embryo preservation and fossilization are crucial for a reliable interpretation of their phylogenetic position. We conducted phosphatization experiments on eggs of the marbled crayfish Procambarus that indicate a close link between early mineralization and rapid anaerobic decay of the endochorional envelope. Our experiments replicated the different preservational stages of degradation observed in the fossil record. Stabilization of the spherical morphology was achieved by pre-heating of the eggs. Complete surface mineralization occurred under reduced conditions within one to two weeks, with fine-grained brushite (CaHPO4 · 2H2O) and calcite. The mechanisms of decay, preservation of surface structures, and mineral replacement in the experiment were likely similar during fossilization of Cambrian embryos.

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5

Saitta, Evan T., Chris Rogers, Richard A. Brooker, Geoffrey D. Abbott, Sumit Kumar, Shane S. O'Reilly, Paul Donohoe, Suryendu Dutta, Roger E. Summons y Jakob Vinther. "Low fossilization potential of keratin protein revealed by experimental taphonomy". Palaeontology 60, n.º 4 (8 de mayo de 2017): 547–56. http://dx.doi.org/10.1111/pala.12299.

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Purnell, Mark A., Philip J. C. Donoghue, Sarah E. Gabbott, Maria E. McNamara, Duncan J. E. Murdock y Robert S. Sansom. "Experimental analysis of soft-tissue fossilization: opening the black box". Palaeontology 61, n.º 3 (20 de marzo de 2018): 317–23. http://dx.doi.org/10.1111/pala.12360.

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7

Farr, Fiona. "Plateaux in pronunciation". TEANGA, the Journal of the Irish Association for Applied Linguistics 20 (8 de octubre de 2020): 53–66. http://dx.doi.org/10.35903/teanga.v20i.504.

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Within the field of second language acquisition the question of cessation of learning short of the target language norms, particularly among adult populations, has been widely discussed since the term FOSSILIZATION was first coined by Selinker in 1972. This article briefly outlines the main theoretical concerns of this phenomenon, which has had various terminological badges over the past three decades. It then details an experimental study whose aim it was to uncover the destabilizing potential of instruction on the pronunciation of advanced French learners of English as a Foreign Language who displayed fossilization tendencies. The results indicate significant improvements made by the experimental group relative to the control group. In conclusion it is deemed appropriate to classify such learners as stabilized and not permanently fossilized, as changes in pronunciation systems can occur give optimal conditions of learning and exposure.

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8

Newman, S. A., V. Klepac-Ceraj, G. Mariotti, S. B. Pruss, N. Watson y T. Bosak. "Experimental fossilization of mat-forming cyanobacteria in coarse-grained siliciclastic sediments". Geobiology 15, n.º 4 (11 de febrero de 2017): 484–98. http://dx.doi.org/10.1111/gbi.12229.

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Hajar, Sitti, Eka Prabawati Rum y Ika Sastrawati. "IMPLEMENTING HYPERCORRECTION APPROACH TO REDUCE THE STUDENTS FOSSILIZATION IN ENGLISH PRONUNCIATION AT SMA NEGERI 7 SELAYAR". English Language Teaching Methodology 3, n.º 3 (30 de diciembre de 2023): 257–63. http://dx.doi.org/10.56983/eltm.v3i3.306.

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The purpose based on this research was to find out whether or not the hypercorrection approach reduces the student’s fossilization in English pronunciation at SMA Negeri 7 Selayar. The researcher used a pre-experimental design and quantitative method using one class for a pre-test and post-test.In the 2022–2023 academic year, the population of this study were 32 students of class 10 IPA at SMA Negeri 7 Selayar. To determine the research sample, cluster sampling method is used. The speaking test is used a data collection method.The results show of the study show that the application of the hypercorrection approach can reduce the fossilization of students’ pronunciation in vowels (/i:/, /I/, /e/, /æ/). This is evidenced by using pre-test scores (39.53) and a post-tests score(72.18), which shows that in addition to the test scores, students’ pronunciation in the post-test is higher than the pre-test. (29.10) which is higher based on the t-table value (1.696). As a result, the Null hypothesis was refuted and the alternative hypothesis was adopted. In the study the researcher came to the conclusion that Hypercorrection reduces student’s fossilization of pronunciation.

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Slagter, Silvina, Lidya G. Tarhan, Weiduo Hao, Noah J. Planavsky y Kurt O. Konhauser. "Experimental evidence supports early silica cementation of the Ediacara Biota". Geology 49, n.º 1 (4 de septiembre de 2020): 51–55. http://dx.doi.org/10.1130/g47919.1.

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Abstract Casts and molds of soft-bodied organisms in Ediacaran sandstones (“Ediacara-style” fossilization) have played an important role in reconstruction of the emergence and radiation of early complex macroscopic life. However, the preservational processes responsible for the Ediacara fossil record are still vigorously debated. Whereas classic studies proposed fossilization via rapid sulfide mineralization of carcass and matground surfaces, a more recent view posits silica as the key mineral involved in their preservation. We performed experiments in which a variety of soft-bodied organisms were exposed to silica-rich solutions at concentrations considered characteristic of Ediacaran seawater (2 mM). Our results document continuous precipitation of amorphous silica onto the surfaces of these organic tissues under constant and normal marine pH values (7.8). Mineral formation was accompanied by a progressive decrease in the dissolved silica (DSi) concentration of the experimental solution to levels well below amorphous silica saturation. Additionally, we find that the magnitude of silica precipitation is correlated to each organism’s functional-group chemistry, as measured by potentiometric acid-base titrations. We suggest that a wide range of soft-bodied organisms were prone to silicification in Ediacaran marine environments characterized by anactualistically high DSi concentrations. This provides further support for the model that the extraordinary moldic preservation of the Ediacara Biota was promoted by early silica cementation and that this mode of preservation can offer an accurate glimpse into the composition of those early animal ecosystems.

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Odin, Giliane P., Maria E. McNamara, Hans Arwin y Kenneth Järrendahl. "Experimental degradation of helicoidal photonic nanostructures in scarab beetles (Coleoptera: Scarabaeidae): implications for the identification of circularly polarizing cuticle in the fossil record". Journal of The Royal Society Interface 15, n.º 148 (noviembre de 2018): 20180560. http://dx.doi.org/10.1098/rsif.2018.0560.

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Scarab beetles (Coleoptera: Scarabaeidae) can exhibit striking colours produced by pigments and/or nanostructures. The latter include helicoidal (Bouligand) structures that can generate circularly polarized light. These have a cryptic evolutionary history in part because fossil examples are unknown. This suggests either a real biological signal, i.e. that Bouligand structures did not evolve until recently, or a taphonomic signal, i.e. that conditions during the fossilization process were not conducive to their preservation. We address this issue by experimentally degrading circularly polarizing cuticle of modern scarab beetles to test the relative roles of decay, maturation and taxonomy in controlling preservation. The results reveal that Bouligand structures have the potential to survive fossilization, but preservation is controlled by taxonomy and the diagenetic history of specimens. Further, cuticle of specific genus ( Chrysina ) is particularly decay-prone in alkaline conditions; this may relate to the presence of certain compounds, e.g. uric acid, in the cuticle of these taxa.

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12

Hippler, D., N. Hu, M. Steiner, G. Scholtz y G. Franz. "Experimental mineralization of crustacean eggs leads to surprising tissue conservation: new implications for the fossilization of Precambrian-Cambrian embryos". Biogeosciences Discussions 8, n.º 6 (15 de diciembre de 2011): 12051–77. http://dx.doi.org/10.5194/bgd-8-12051-2011.

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Abstract. Phosphatized globular microfossils from the Ediacaran and Lower Cambrian of South China represent an impressive record of early animal evolution and development, however their affinity based on putative embryonic metazoan, bacterial and inorganic features is strongly debated. Understanding key processes and conditions that cause exceptional egg and embryo preservation and fossilization are therefore crucial for a reliable interpretation of their phylogenetic position. Taphonomic experiments on eggs of the marbled crayfish indicate a close link between early mineralization and rapid anaerobic decay of the endochorional envelope, producing different preservational stages of degradation resembling the various decay stages observed in the fossil record. Stabilization of the spherical morphology was achieved by pre-heating of the eggs. Complete surface mineralization occurred under reduced conditions within one to two weeks, with fine-grained brushite (CaHPO4·2H2O) over calcite as the dominating mineral phase. Although the endochorional envelope was not preserved, experiments resulted in exceptional preservation of the embryonic tissue at the cellular level. Thus our findings suggest that the mechanisms of decay, preservation of surface structures, and mineral replacement in the experiment and during fossilization of Cambrian embryos were likely operating at a similar rationale.

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13

Orange, François, Samuel Dupont, Olivier Le Goff, Nadege Bienvenu, Jean-Robert Disnar, Frances Westall y Marc Le Romancer. "Experimental fossilization of the Thermophilic Gram-positive BacteriumGeobacillusSP7A: A Long Duration Preservation Study". Geomicrobiology Journal 31, n.º 7 (17 de julio de 2014): 578–89. http://dx.doi.org/10.1080/01490451.2013.860208.

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14

Beli, Elena, Stefano Piraino y Christopher B. Cameron. "Fossilization processes of graptolites: insights from the experimental decay of Rhabdopleura sp. (Pterobranchia)". Palaeontology 60, n.º 3 (20 de marzo de 2017): 389–400. http://dx.doi.org/10.1111/pala.12290.

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15

Li, Jinhua, Sylvain Bernard, Karim Benzerara, Olivier Beyssac, Thierry Allard, Julie Cosmidis y Julien Moussou. "Impact of biomineralization on the preservation of microorganisms during fossilization: An experimental perspective". Earth and Planetary Science Letters 400 (agosto de 2014): 113–22. http://dx.doi.org/10.1016/j.epsl.2014.05.031.

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SELLY, TARA y JAMES D. SCHIFFBAUER. "X-RAY TOMOGRAPHIC MICROSCOPY AS A MEANS TO SYSTEMATICALLY TRACK EXPERIMENTAL DECAY AND FOSSILIZATION". PALAIOS 36, n.º 6 (23 de junio de 2021): 216–24. http://dx.doi.org/10.2110/palo.2021.004.

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ABSTRACT Laboratory-based decay experiments have become commonly used to supplement our understanding of how organisms enter the fossil record. Differences in how these experiments are designed and evaluated, however, including dissimilarities in qualitative decay-scoring indices superimposed on variability in model organisms, renders any semblance of comparison between studies unreliable. Here, we introduce the utility of X-ray tomographic microscopy (μCT) as a means for reliable and repeatable analysis of soft-tissue decay experiment products. As proof-of-concept, we used a relatively simple experimental design with classic studies as comparators, and present our analytical protocol using μCT for capturing the entire volume of the decay subject. Segmentation software then allows for 3D volume analysis and high-resolution internal and external character identification. We describe the workflow from sample preparation, contrast-staining, and data collection to processing and analysis of the resulting data, using peppermint shrimp (Lysmata wurdemanni) as model organisms, and compare our results to previous taphonomic studies. These methods allow for improved visualization and quantification of decay and internal volume analysis with minimal handling as compared to traditional qualitative scoring methods. Using the same scoring criteria as previous studies, this study revealed similar decay results for certain features, while we were additionally able to detect other feature loss or alteration earlier—importantly without need for potentially distortive sample handling. We conclude that μCT is a more effective, straightforward, and exact means for extracting quantitative data on the progression of decay and should be adopted in future studies, where available, to streamline and standardize comparisons.

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Li, Jinhua, Karim Benzerara, Sylvain Bernard y Olivier Beyssac. "The link between biomineralization and fossilization of bacteria: Insights from field and experimental studies". Chemical Geology 359 (noviembre de 2013): 49–69. http://dx.doi.org/10.1016/j.chemgeo.2013.09.013.

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18

Butler, Aodhán D., John A. Cunningham, Graham E. Budd y Philip C. J. Donoghue. "Experimental taphonomy of Artemia reveals the role of endogenous microbes in mediating decay and fossilization". Proceedings of the Royal Society B: Biological Sciences 282, n.º 1808 (7 de junio de 2015): 20150476. http://dx.doi.org/10.1098/rspb.2015.0476.

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Exceptionally preserved fossils provide major insights into the evolutionary history of life. Microbial activity is thought to play a pivotal role in both the decay of organisms and the preservation of soft tissue in the fossil record, though this has been the subject of very little experimental investigation. To remedy this, we undertook an experimental study of the decay of the brine shrimp Artemia , examining the roles of autolysis, microbial activity, oxygen diffusion and reducing conditions. Our findings indicate that endogenous gut bacteria are the main factor controlling decay. Following gut wall rupture, but prior to cuticle failure, gut-derived microbes spread into the body cavity, consuming tissues and forming biofilms capable of mediating authigenic mineralization, that pseudomorph tissues and structures such as limbs and the haemocoel. These observations explain patterns observed in exceptionally preserved fossil arthropods. For example, guts are preserved relatively frequently, while preservation of other internal anatomy is rare. They also suggest that gut-derived microbes play a key role in the preservation of internal anatomy and that differential preservation between exceptional deposits might be because of factors that control autolysis and microbial activity. The findings also suggest that the evolution of a through gut and its bacterial microflora increased the potential for exceptional fossil preservation in bilaterians, providing one explanation for the extreme rarity of internal preservation in those animals that lack a through gut.

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19

Schnitzer, Marc L. "Steady as a rock: Does the steady state represent cognitive fossilization?" Journal of Psycholinguistic Research 22, n.º 1 (enero de 1993): 1–20. http://dx.doi.org/10.1007/bf01068154.

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20

Naimark, Elena, Maria Kalinina, Alexander Shokurov, Alexander Markov, Liubov Zaytseva y Natalia Boeva. "Mineral composition of host sediments influences the fossilization of soft tissues". Canadian Journal of Earth Sciences 55, n.º 11 (noviembre de 2018): 1271–83. http://dx.doi.org/10.1139/cjes-2017-0237.

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Cambrian Lagerstätten host rocks are frequently composed of kaolinite and chlorite in varying amounts; accordingly, our goal was to study the preservation potential of crustaceans in these two clays. We conducted long-term experiments (12–18 months, the longest duration of actualistic taphonomy experiments from published literature) on the decay of Artemia salina in these clay sediments. The degree of preservation, transformed mineralogical composition of the sediments, and the elemental composition of the nauplial remains were examined. We demonstrate that the kaolinite and chlorite sediment enhanced the preservation (in the kaolinite the effect was considerably higher than in the chlorite) compared with the sediment-free control. pH inside the sediments dropped to 6.5–7.1 and was even lower (<4) around the buried carcasses, facilitating the dissolution of clays. This phenomenon was confirmed by mineralogical analyses of the experimental sediments, which showed mineralogical signatures of such dissolution and new mineral phases. According to the variations in the dissolved minerals in the sediments, different cations entered the buried remains as was shown by the multiple energy dispersive X-ray analyses. An increased level of Mg was detected in the carcasses buried in chlorite, whereas Al and Si concentrations were higher in the kaolinite; in both cases, Ca rapidly entered the decaying tissues from marine water. Bacteria underwent similar mineralization as the macroremains and apparently had no direct effect on the mineralization. The results confirmed an important role of dissolved Al ions in preservation of soft-bodied organisms in clay-dominated sediments and explained wide variation in chemical composition of their fossils.

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Afanasieva, Marina S. "Experimental evidence for changes during fossilization of radiolarian tests and implications for a model of biomineralization". Marine Micropaleontology 15, n.º 3-4 (marzo de 1990): 233–48. http://dx.doi.org/10.1016/0377-8398(90)90013-c.

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Guo, Jun Jing y Wen Bin Chen. "The Adsorption of Copper Ions by Sodium Alginate Immobilized Bacillus Subtilis Body and Purify Copper of Mine Wastewater". Advanced Materials Research 356-360 (octubre de 2011): 1469–74. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.1469.

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In this study, calcium alginate immobilized bacillus subtilis body was used as an adsorbent for the aim of adsorpting Cu(Ⅱ) ions form the aqueous solutions, On sutiable condition, this study use purely bacteria eliminate other bacteria come in life-form bacteria .Through the orthogonal experiment obtains the optimum condition of sodium alginate fossilization bacillus subtilus pellet to the Cu(Ⅱ) adsorption, The biosorption efficiency was strongly influenced by the pH and the initial concentration ofthe Cu(Ⅱ) aqueous solutions. We also discusses the influence of single factor to the sodium alginate fossilization bacillus subtilus pellet to the Cu(Ⅱ) adsorption ,which included pH, contact time, temperature, initial metal ion concentrations and ionic strength in the adsorption process. The adsorption of the adsorbent on Cu(Ⅱ) is related to its concentration . From the research,we know the maximum adsorption rate to the Cu(Ⅱ) is about 83.2%. Using different model to analyse data. The sorption process follows pseudo-second-order kinetics very well,and the correlation coefficients R all reached to 0.9, and the rate constant of this kinetics model for the adsorption processes, k2, increased with the increasing temperatures. The isothermal data could be well described by the Langmuir adsorption isothermal equations．The experimental results showed that heavy metals could be eficciently accumulated by the immobilized bacteria.

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McNamara, Maria E., Derek E. G. Briggs, Patrick J. Orr, Daniel J. Field y Zhengrong Wang. "Experimental maturation of feathers: implications for reconstructions of fossil feather colour". Biology Letters 9, n.º 3 (23 de junio de 2013): 20130184. http://dx.doi.org/10.1098/rsbl.2013.0184.

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Fossil feathers often preserve evidence of melanosomes—micrometre-scale melanin-bearing organelles that have been used to infer original colours and patterns of the plumage of dinosaurs. Such reconstructions acknowledge that evidence from other colour-producing mechanisms is presently elusive and assume that melanosome geometry is not altered during fossilization. Here, we provide the first test of this assumption, using high pressure–high temperature autoclave experiments on modern feathers to simulate the effects of burial on feather colour. Our experiments show that melanosomes are retained despite loss of visual evidence of colour and complete degradation of other colour-producing structures (e.g. quasi-ordered arrays in barbs and the keratin cortex in barbules). Significantly, however, melanosome geometry and spatial distribution are altered by the effects of pressure and temperature. These results demonstrate that reconstructions of original plumage coloration in fossils where preserved features of melanosomes are affected by diagenesis should be treated with caution. Reconstructions of fossil feather colour require assessment of the extent of preservation of various colour-producing mechanisms, and, critically, the extent of alteration of melanosome geometry.

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Kaesler, Roger L., Mervin Kontrovitz y Stefanie Taunton. "Crushing strength ofPuriana pacifica(Ostracoda), an experimental approach to taphonomy". Journal of Paleontology 67, n.º 6 (noviembre de 1993): 1005–10. http://dx.doi.org/10.1017/s0022336000025324.

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Specimens of the ostracode speciesPuriana pacificaBenson, 1959, from a modern assemblage from the Gulf of California can be sorted by visual inspection into five groups based on taphonomic condition. Characteristics used for sorting include: presence or absence of appendages; color and opacity of the valves; and evidence of abrasion, fragmentation, and boring. As measured by resistance to crushing force, members of the five groups show appreciable, progressive, postmortem weakening so that specimens in the poorest apparent condition are the weakest mechanically. The groups also differ in style of fracturing in response to crushing force. Fractures of valves of the freshest specimens are located quite consistently. Among specimens with progressively more damage, the location of fractures becomes less predictable. On valves of the most damaged specimens, typical fractures are short and likely to occur almost anywhere on the valve. These experimental results emphasize the importance of rapid burial in enhancing the likelihood of fossilization. Furthermore, they cast doubt on the ability of paleoecologists to use valves and carapaces of fossil ostracodes to interpret levels of wave and current energy in ancient environments because taphonomic weakening and subsequent destruction may effectively mask functional morphology.

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Sahni, Ashok y Asit Jolly. "Status of taphonomical studies in India: A review". Journal of Palaeosciences 44 (31 de diciembre de 1995): 29–37. http://dx.doi.org/10.54991/jop.1995.1199.

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Taphonomy, a sub-branch of palaeontology, is defined as the study of the sequence of events beginning with the death of an organism and its subsequent deposition and fossilization. The present paper outlines important areas in which the work has been done on this subject and also attempts to review the Indian contributions. The conditions of the burial and the preservation of nests and eggshell fragments of dinosaurs provide ample for taphonomic analysis. There is a need for experimental study on dispersal, disintegration, preservation and diagenesis of organic fossils. In puts from sedimentology are essential and only an interdisciplinary effort can result in any success to build the postmortem history of plants and animals.

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Kropacheva, Yu E., S. V. Zykov, N. G. Smirnov y R. M. Salimov. "Dental microwear and mesovear of Microtus voles before and after experimental feeding of owls". Доклады Академии наук 486, n.º 5 (20 de junio de 2019): 638–42. http://dx.doi.org/10.31857/s0869-56524865638-642.

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Form of expressions of dental microwear and mesovear of small mammals depends on abrasiveness, hardness and a number of other characteristics of the feed. Analysis of micro- and mesorelief is used on paleontological materials for the reconstruction of some parameters of the animals diet. Small mammals move a hard way from objects of biocenoses to fossils. Bone remains are modified in the process of accumulation and fossilization. In particular, bone remains from ornithogenous deposits were influenced to the substances of the digestive system of birds. In this work, an experimental estimation was made of the degree of changes in a number of characteristics of narrow-headed vole molars (Microtus gregalis) from the pellets of two species of owls. On the same samples before and after exposure to substances of the digestive system of a Polar Owl (Nyctea scandiaca) and Eagle Owl (Bubo bubo), it was shown that the microrelief of the tooth enamel undergoes serious changes and haven't information about the in vivo diet of the voles. A different degree of preservation of the mesoreliefs characteristic was shown. An assessment of their applicability for paleoreconstructions depending on this was given.

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Hercman, Helena, Marek Szczerba, Paweł Zawidzki y Agata Trojan. "Carbon isotopes in wood combustion/pyrolysis products: experimental and molecular simulation approaches". Geochronometria 46, n.º 1 (19 de julio de 2019): 111–24. http://dx.doi.org/10.1515/geochr-2015-0110.

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Abstract A series of laboratory experiments was performed to determine the carbon stable isotopic composition of different combustion/pyrolysis (B/P) products. Variation in the δ13C values of the products was observed, up to 4‰. The differences in the carbon isotopic compositions of the B/P products were dependent on temperature, time and wood type. Comparison of the results for fresh and fossil oak wood suggested that the δ13C differences were the effect of selective decomposition of some wood components during the fossilization process. The temperature dependence of the carbon isotopic composition was linked to variation in the carbon isotopic composition of the main wood components, which each had different levels of thermal stability. Isotopes exchange reactions in between different products can be also considered as possible source of variation of δ13C on temperature. Both these hypotheses were supported by molecular simulations of cellulose and lignin B/P. The results confirm that B/P should be treated as a continuous process, where the results depend on the degree of process development. Natural burning processes are dynamic and burning conditions change rapidly and it is necessary to take care when using combustion products as a paleoenvironmental proxy or as an isotopic characteristic for the identification of source material.

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da Silva, João Hermínio, Francisco Eduardo de Sousa Filho, Antônio Álamo Feitosa Saraiva, Nádia Amanda Andrade, Bartolomeu Cruz Viana, Juliana Manso Sayão, Bruno Tavares de Oliveira Abagaro, Paulo de Tarso Cavalcante Freire y Gilberto Dantas Saraiva. "Spectroscopic Analysis of a Theropod Dinosaur (Reptilia, Archosauria) from the Ipubi Formation, Araripe Basin, Northeastern Brazil". Journal of Spectroscopy 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/437439.

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The Araripe Sedimentary Basin is known by the excellence of its fossils, regarding the preservation, diversity, and quantity. Here, we present a spectroscopic analysis using several experimental techniques (X-ray energy dispersion spectroscopy, Fourier-transform infrared spectroscopy) as well as X-ray diffraction and thermogravimetric analysis applied in small fragments of bones from the posterior members of a theropod dinosaur. The results agree regarding the different composition of the stone matrix and the fossilized bone, indicating a partial substitution of the material by elements present in the depositional environment. However, differently from what is believed to occur, there is evidence that pyritization is not the only mechanism of fossilization for a specimen of Ipubi formation, but calcification, additionally, plays an important role in the fossil production of this Formation.

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Cunningham, J. A., C. W. Thomas, S. Bengtson, F. Marone, M. Stampanoni, F. R. Turner, J. V. Bailey, R. A. Raff, E. C. Raff y P. C. J. Donoghue. "Experimental taphonomy of giant sulphur bacteria: implications for the interpretation of the embryo-like Ediacaran Doushantuo fossils". Proceedings of the Royal Society B: Biological Sciences 279, n.º 1734 (7 de diciembre de 2011): 1857–64. http://dx.doi.org/10.1098/rspb.2011.2064.

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The Ediacaran Doushantuo biota has yielded fossils interpreted as eukaryotic organisms, either animal embryos or eukaryotes basal or distantly related to Metazoa. However, the fossils have been interpreted alternatively as giant sulphur bacteria similar to the extant Thiomargarita . To test this hypothesis, living and decayed Thiomargarita were compared with Doushantuo fossils and experimental taphonomic pathways were compared with modern embryos. In the fossils, as in eukaryotic cells, subcellular structures are distributed throughout cell volume; in Thiomargarita , a central vacuole encompasses approximately 98 per cent cell volume. Key features of the fossils, including putative lipid vesicles and nuclei, complex envelope ornament, and ornate outer vesicles are incompatible with living and decay morphologies observed in Thiomargarita . Microbial taphonomy of Thiomargarita also differed from that of embryos. Embryo tissues can be consumed and replaced by bacteria, forming a replica composed of a three-dimensional biofilm, a stable fabric for potential fossilization. Vacuolated Thiomargarita cells collapse easily and do not provide an internal substrate for bacteria. The findings do not support the hypothesis that giant sulphur bacteria are an appropriate interpretative model for the embryo-like Doushantuo fossils. However, sulphur bacteria may have mediated fossil mineralization and may provide a potential bacterial analogue for other macroscopic Precambrian remains.

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NEWMAN, SHARON A., MIRNA DAYE, SIRINE C. FAKRA, MATTHEW A. MARCUS, MIHKEL PAJUSALU, SARA B. PRUSS, EMILY F. SMITH y TANJA BOSAK. "EXPERIMENTAL PRESERVATION OF MUSCLE TISSUE IN QUARTZ SAND AND KAOLINITE". PALAIOS 34, n.º 9 (26 de septiembre de 2019): 437–51. http://dx.doi.org/10.2110/palo.2019.030.

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ABSTRACT Siliciclastic sediments of the Ediacaran Period contain exceptionally preserved fossils of macroscopic organisms, including three-dimensional casts and molds commonly found in sandstones and siltstones and some two-dimensional compressions reported in shales. The sporadic and variable associations of these exceptionally preserved macroscopic fossils with pyrite, clay minerals, and microbial fossils and textures complicate our understanding of fossilization processes. This hinders inferences about the evolutionary histories, tissue types, original morphologies, and lifestyles of the enigmatic Ediacara biota. Here, we investigate the delayed decay of scallop muscles buried in quartz sand or kaolinite for 45 days. This process occurs in the presence of microbial activity in mixed redox environments, but in the absence of thick, sealing microbial mats. Microbial processes that mediate organic decay and release the highest concentrations of silica and Fe(II) into the pore fluids are associated with the most extensive tissue decay. Delayed decay and the preservation of thick muscles in sand are associated with less intense microbial iron reduction and the precipitation of iron oxides and iron sulfides that contain Fe(II) or Fe(III). In contrast, muscles buried in kaolinite are coated only by <10 μm-thick clay veneers composed of kaolinite grains and newly formed K- and Fe(II)-rich aluminosilicate phases. Muscles that undergo delayed decay in kaolinite lose more mass relative to the muscles buried in sand and undergo vertical collapse. These findings show that the composition of minerals that coat or precipitate within the tissues and the vertical dimension of the preserved features can depend on the type of sediment that buries the muscles. Similar processes in the zone of oscillating redox likely facilitated the formation of exceptionally preserved macrofossils in Ediacaran siliciclastic sediments.

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Nanglu, Karma, Jean-Bernard Caron y Christopher B. Cameron. "Using experimental decay of modern forms to reconstruct the early evolution and morphology of fossil enteropneusts". Paleobiology 41, n.º 3 (junio de 2015): 460–78. http://dx.doi.org/10.1017/pab.2015.11.

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AbstractDecay experiments are becoming a more widespread tool in evaluating the fidelity of the fossil record. Character interpretations of fossil specimens stand to benefit from an understanding of how decay can result in changes in morphology and, potentially, total character loss. We performed a decay experiment for the Class Enteropneusta to test the validity of anatomical interpretations of the Burgess Shale enteropneust Spartobranchus tenuis and to determine how the preservation of morphological features compares with the sequence of character decay in extant analogues. We used three species of enteropneust (Saccoglossus pusillus, Harrimania planktophilus, and Balanoglossus occidentalis) representing the two major families of Enteropneusta. Comparisons between decay sequences suggest that morphological characters decay in a consistent and predictable manner within Enteropneusta, and do not support the hypothesis of stemward slippage. The gill bars and nuchal skeleton were the most decay resistant, whereas the gill pores and pre-oral ciliary organ were unequivocally the most decay prone. Decay patterns support the identification of the nuchal skeleton, gill bars, esophageal organ, trunk, and proboscis in Spartobranchus tenuis and corroborate a harrimaniid affinity. Bias due to the taphonomic loss of taxonomically informative characters is unlikely. The morphologically simple harrimaniid body plan can be seen, therefore, to be plesiomorphic within the enteropneusts. Discrepancies between the sequence of decay in a laboratory setting and fossil preservation also exist. These discrepancies are highlighted not to discredit the use of modern decay studies but rather to underline their non-actualistic nature. Paleoenvironmental variables besides decay, such as the timeframe between death and early diagenesis as well as postmortem transport, are discussed relative to decay data. These experiments reinforce the strength of a comprehensive understanding of decay sequences as a benchmark against which to describe fossil taxa and understand the conditions leading to fossilization.

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Carpenter, Kenneth. "Hydraulic modeling and computational fluid dynamics of bone burial in a sandy river channel". Geology of the Intermountain West 7 (30 de abril de 2020): 97–120. http://dx.doi.org/10.31711/giw.v7.pp97-120.

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An oval recycling flume with live-beds (moveable) of medium and very coarse grained sands were used to explore the process of bone burial as a precursor to fossilization. Two-dimentional computation fluid dynamics was used to visualize and interpret the flow turbulence around bones. Results show that a water mass approaching and passing a static bone (obstruction) is subjected to flow modification by flow separation, flow constriction, and flow acceleration producing complex flow patterns (turbulence). These complex patterns include an upstream high-pressure zone, down flows, and vortices (with flow reversal near the bed) causing bed shear stress that produce bed erosion. Downstream of the bone, the water mass undergoes flow deceleration, water recirculation (turbulence eddies), flow reattachment, low-pressure zone (drag), and sediment deposition. Scour plays a crucial role by undercutting bone on the upstream side and may cause the bone to settle into the bed by rotation or sliding. Scour geometry is determined by bone size and shape, approaching flow velocity and angle to flow, flow depth, bed topography, and bed friction. Drag on the downstream side of the bone causes scoured sediment deposition, but burial by migrating bed forms is the most important method of large bone burial. Bone may be repeatedly buried and exposed with renewed scour. However, each episode of scour may lower the bone deeper into the bed so that it essentially buries itself. No difference in these effects were noted between experiments using fine or coarse grain sizes. This experimental work is then used to interpret the possible history of bone burial in the Upper Jurassic Morrison Formation on the bone wall inside the Quarry Exhibit Hall at Dinosaur National Monument, Utah.

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Иванов, В. П., А. А. Дмитриенко, И. В. Рычкова, Е. Р. Исаева, Т. В. Тимкин, Д. А. Болдина y М. Г. Пахтаева. "POSSIBILITIES OF DIFFUSE REFLECTION INFRARED SPECTROSCOPY FOR STUDYING ORGANIC SUBSTANCES OF CAUSTOBIOLITES". Koks i khimiya, n.º 5 (25 de mayo de 2023): 33–46. http://dx.doi.org/10.52351/00232815_2023_05_33.

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Предложенный подход изучения организации структуры каустобиолитов сингенетического ряда на основе инфракрасной спектроскопии диффузного отражения позволяет определять их сходство и различие независимо от происхождения (фоссилизацию, оторфенение, углефикацию) исходного растительного материала органических веществ. Он опирается на интерпретацию результатов структурно-группового и структурно-генетического анализов, позволяющих выявлять особенности образования. Проведены экспериментальные исследования образцов гумусового (торф, фитолейма хвоща, уголь пласта) и сапропелевого (донный осадок, фитолейма проптеридофита, липтобиолитовый уголь) происхождения углефицированных веществ. Результаты показывают, что применение отдельных функциональных групп связей химических элементов (C, N, O, H, S, Si), сгруппированных в виде функциональных структурных единиц, могут в структурах углефицированных веществ позиционироваться в виде кларатов. Клараты дают дополнительные сведения как об изменчивости строения растений-углеобразователей в виде фитолеймы (остатка растения) под влиянием обугливания (фоссилизация), так и о структурном преобразовании растений-углеобразователей в виде осадков под влиянием оторфенения, а в последующем под влиянием углефикации торфов и осадков в угли. Установлено, что функциональные структурные единицы как клараты дают однозначную идентификацию плоскостных и межплоскостных связей в структурах углефицированных веществ и позволяют выделять формообразующие связи в виде функциональных структурных единиц, а в целом характеризовать данный вид анализа как структурно-кластерный. An approach to the study of the organization of the structure of syngenetic series caustobiolites based on diffuse reflection infrared spectroscopy is proposed. This method makes it possible to determine the similarity and difference of caustobiolites regardless of the origin of the original plant material of organic substances (fossilization, detoxification, carbonification). The method is based on the interpretation of the results of structural-group and structural-genetic analyses, which make it possible to identify the features of genesis. Experimental studies of samples of humus (peat, horsetail phytoleimum, coal formation) and sapropel (bottom sediment, propteridophyte phytoleimum, liptobiolite coal) origin of carbonified substances were carried out. The results show that the use of separate functional groups of chemical element bonds (C, N, O, H, S, Si) grouped in the form of functional structural units can be positioned in the structures of carbonified substances in the form of clarates. Clarates provide additional information about the variability of the structure of carbon-forming plants under the influence of charring, detoxification and subsequent carbonification. It has been established that functional structural units as clarates provide unambiguous identification of planar and interplane connections in the structures of carbonified substances. they allow us to distinguish formative connections in the form of functional structural units, and in general characterize this type of analysis as structural-cluster.

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Amaya Dueñas, Diana Maria, Dirk Ullmer, Marc Riedel, Marius Tomberg, Daniele Fortunati, Marc P. Heddrich y S. Asif Ansar. "Operating Strategies for Fischer-Tropsch Tail Gas Recirculation on a 100 kW SOEC Reactor". ECS Meeting Abstracts MA2023-01, n.º 54 (28 de agosto de 2023): 305. http://dx.doi.org/10.1149/ma2023-0154305mtgabs.

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The efficient use of CO2 and its conversion into CO via high temperature electrolysis is considered as a suitable route for the de-fossilization of anthropogenic activities. Within electrochemical solid oxide cells reactors (SOCs), the co-electrolysis of H2O and CO2 at high temperature (above 800 °C) yields syngas (H2 + CO), one of the most important feedstocks for the production of synthetic fuels and chemicals, e. g. via the Fischer-Tropsch process. At the Institute of Engineering Thermodynamics of the German Aerospace Center (DLR) in Stuttgart Germany, a unique test environment (Galactica) for investigating SOC reactors has been designed and constructed with the aim to deepen the research at the 100 kW-scale reactor in commercial systems. State-of-the-Art SOCs have shown promising results that allow the scale-up to larger, industrially relevant systems sizes. With Galactica, DLR was able to demonstrate successfully how 100 kW-scale reactors are a suitable stepping stone towards multi MW-scale process systems. However, operating strategies are required in order to understand how these systems would perform when steady-state operation cannot be guaranteed and unexpected shortages on the feedstocks and electricity could arise. In this work, the coupling of a 100 kW SOC reactor (consisting of 24 single SOC stacks) with the tail gas recirculation of a Fischer-Tropsch reactor will be presented. The main motivation is to improve the overall process efficiency, increase the conversion (since tail gas hydrocarbons will be reformed) and reduce the net material consumption [1] [2]. By emulating the tail gas composition from the Fischer-Tropsch reactor, different syngas ratios (H2/CO) were investigated in Galactica, not only experimentally but also with the support of the in-house simulation framework TEMPEST [3], specialized for transient simulations on electrochemical reactors. Different operating conditions were evaluated by: (i) adding CH4 at open circuit voltage (OCV) and under current, (ii) performing an experimental ramp of the emulated Fischer-Tropsch gas composition into the inlet gases of the SOC reactor and (iii) by simulating a Feed-Forward controller in the case of H2O and CO2 shortages by varying the current and the air flow values in order to keep the operating temperature and reactor conversion in stable conditions. These results will allow to evaluate the performance of the SOC reactor with the temperature profile along the cells and the stacks, as well as with the syngas ratio behaviour. In this regard, operation strategies will be analyzed and discussed with the aim to mitigate failure conditions on SOC reactors, while operating in transient conditions in the frame of syngas production via high temperature co-electrolysis. [1] Herz, G.; Reichelt, E.; Jahn, M., Techno-economic analysis of a co-electrolysis-based synthesis process for the production of hydrocarbons. Applied Energy 2018, 215, 309-320 [2] Cinti, G.; Baldinelli, A.; Di Michele, A.; Desideri, U., Integration of Solid Oxide Electrolyzer and Fischer-Tropsch: A sustainable pathway for synthetic fuel. Applied Energy 2016, 162, 308-320. [3] Tomberg, M.; Heddrich, M. P.; Sedeqi, F.; Ullmer, D.; Ansar, S. A.; Friedrich, K. A., A New Approach to Modeling Solid Oxide Cell Reactors with Multiple Stacks for Process System Simulation. J. Electrochem. Soc 2022, 169, 054530.

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Slagter, Silvina, Weiduo Hao, Noah J. Planavsky, Kurt O. Konhauser y Lidya G. Tarhan. "Biofilms as agents of Ediacara-style fossilization". Scientific Reports 12, n.º 1 (23 de mayo de 2022). http://dx.doi.org/10.1038/s41598-022-12473-1.

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AbstractEarth’s earliest fossils of complex macroscopic life are recorded in Ediacaran-aged siliciclastic deposits as exceptionally well-preserved three-dimensional casts and molds, known as “Ediacara-style” preservation. Ediacara-style fossil assemblages commonly include both macrofossils of the enigmatic Ediacara Biota and associated textural impressions attributed to microbial matgrounds that were integral to the ecology of Ediacara communities. Here, we use an experimental approach to interrogate to what extent the presence of mat-forming microorganisms was likewise critical to the Ediacara-style fossilization of these soft-bodied organisms. We find evidence that biofilms can play an instrumental role in fostering fossilization. Rapid silica precipitation associated with macroorganism tissues is enhanced in the presence of mat- and biofilm-forming microorganisms. These results indicate that the occurrence of microbial mats and biofilms may have strongly shaped the preservational window for Ediacara-style fossils associated with early diagenetic silica cements, and therefore influenced the distribution and palaeoecological interpretation of the Ediacara Biota fossil record.

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Gäb, Fabian, Gabriele Bierbaum, Richard Wirth, Christoph Bultmann, Brianne Palmer, Kathrin Janssen y Sabina Karačić. "Enzymatic phosphatization of fish scales—a pathway for fish fossilization". Scientific Reports 14, n.º 1 (9 de abril de 2024). http://dx.doi.org/10.1038/s41598-024-59025-3.

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AbstractPhosphatized fish fossils occur in various locations worldwide. Although these fossils have been intensively studied over the past decades they remain a matter of ongoing research. The mechanism of the permineralization reaction itself remains still debated in the community. The mineralization in apatite of a whole fish requires a substantial amount of phosphate which is scarce in seawater, so the origin of the excess is unknown. Previous research has shown that alkaline phosphatase, a ubiquitous enzyme, can increase the phosphate content in vitro in a medium to the degree of saturation concerning apatite. We applied this principle to an experimental setup where fish scales were exposed to commercial bovine alkaline phosphatase. We analyzed the samples with SEM and TEM and found that apatite crystals had formed on the remaining soft tissue. A comparison of these newly formed apatite crystals with fish fossils from the Solnhofen and Santana fossil deposits showed striking similarities. Both are made up of almost identically sized and shaped nano-apatites. This suggests a common formation process: the spontaneous precipitation from an oversaturated solution. The excess activity of alkaline phosphatase could explain that effect. Therefore, our findings could provide insight into the formation of well-preserved fossils.

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Jacquemot, Pierre, Jean-Christophe Viennet, Sylvain Bernard, Corentin Le Guillou, Baptiste Rigaud, Ludovic Delbes, Thomas Georgelin y Maguy Jaber. "The degradation of organic compounds impacts the crystallization of clay minerals and vice versa". Scientific Reports 9, n.º 1 (diciembre de 2019). http://dx.doi.org/10.1038/s41598-019-56756-6.

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AbstractExpanding our capabilities to unambiguously identify ancient traces of life in ancient rocks requires laboratory experiments to better constrain the evolution of biomolecules during advanced fossilization processes. Here, we submitted RNA to hydrothermal conditions in the presence of a gel of Al-smectite stoichiometry at 200 °C for 20 days. NMR and STXM-XANES investigations revealed that the organic fraction of the residues is no longer RNA, nor the quite homogeneous aromatic-rich residue obtained in the absence of clays, but rather consists of particles of various chemical composition including amide-rich compounds. Rather than the pure clays obtained in the absence of RNA, electron microscopy (SEM and TEM) and diffraction (XRD) data showed that the mineralogy of the experimental residues includes amorphous silica and aluminosilicates mixed together with nanoscales phosphates and clay minerals. In addition to the influence of clay minerals on the degradation of organic compounds, these results evidence the influence of the presence of organic compounds on the nature of the mineral assemblage, highlighting the importance of fine-scale mineralogical investigations when discussing the nature/origin of organo-mineral microstructures found in ancient rocks.

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Iroegbu, Austine Ofondu Chinomso y Suprakas Sinha Ray. "On the chemistry of furfuryl alcohol polymerization: A review". Journal of Polymer Science, 22 de noviembre de 2023. http://dx.doi.org/10.1002/pol.20230708.

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AbstractThis review dives into the intricate chemistry of furfuryl alcohol (FA) polymerization, a critical process for producing FA‐based resins (oligomers and polymers). Despite over a century of studies, the complexity of FA resinification continues to intrigue scientists, engendering extensive discourses. The inherent complexity and heterogeneity of FA resins have thwarted attempts to propose a universally applicable structural elucidation, prompting the investigation of numerous proposed mechanisms. Drawing upon an extensive corpus of literature, we survey various proposed mechanisms and representative structural attributes of a range of FA polymeric systems. The insights from a rich tapestry of experimental evidence collectively illuminate the manifold intermediates and pathways that characterize various FA polymerization techniques. A critical appraisal of prevailing debates and counterarguments offers a nuanced perspective on the diverse facets of FA polymerization chemistry. Moreover, this work underscores the latent potential of biobased chemistry, from the perspective of furan chemistry, as a potent catalyst for driving the essential objectives of de‐fossilization and sustainability within the chemical and materials industries. Subsequently, it provides valuable insights into the present state of knowledge on FA polymerization, thereby serving as a vanguard for delineating future research trajectories in this captivating field.

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