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Saleh Farid - One of the best experts on this subject based on the ideXlab platform.
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A novel tool to untangle the ecology and Fossil Preservation knot in exceptionally preserved biotas
'Elsevier BV', 2022Co-Authors: Saleh Farid, Pittet Bernard, Lefebvre Bertrand, Ma Xiaoya, Bath-enright, Orla G., Daley, Allison C., Vite Antoine, Mángano M. Gabriela, Buatois, Luis A., Antcliffe, Jonathan B.Abstract:Understanding the functioning of extinct ecosystems is a complicated knot of ecological, evolutionary, and Preservational strands that must be untangled. For instance, anatomical and behavioral differences can profoundly alter Fossilization pathways. This is particularly true in exceptionally preserved soft-bodied biotas that record the earliest phases of animal evolution during the Cambrian Explosion and the Ordovician Radiation. Herein, a novel method of data partitioning based on probabilistic modelling is developed to examine these processes for the Walcott Quarry, Burgess Shale, Canada (510Ma), and the Fezouata Shale, Morocco (c. 475Ma). The modelling shows that the mechanism for soft-tissue Preservation in the Walcott Quarry is ecologically selective, favoring the endobenthos. This is not found in the Fezouata Shale. Taken in concert with bioturbation data, a new model of comparative Preservation is developed based on sedimentary flow dynamics. This suggests that during the Cambrian Explosion and Ordovician Radiation the most exceptional Fossils sites must still be calibrated against each other to understand the unfolding evolutionary events and the ecological structuring of ancient animal communities
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Untangling the ecology and Fossil Preservation knot for Paleozoic Biotas
'Geological Society of America', 2020Co-Authors: Saleh Farid, Bath Enright Orla, Daley Allison, Pittet Bernard, Lefebvre Bertrand, Antcliffe JonathanAbstract:International audienceFossil deposits are a tangle of multiple signals that make understanding the functioning of past ecosystems a complicated and fraught process. The main difficulty is whether differences between Fossil sites show an evolutionary or ecological signal, or are influenced by Fossil Preservation. These processes are not independent, as anatomical or behavioral differences can alter Preservational pathways. It is particularly important to untangle these interacting processes when examining the animal communities of the Cambrian Explosion and Ordovician Radiation, where exceptional Preservation of soft tissues provides relatively complete assemblage data. A novel method of data partitioning based on probabilistic modelling is used to examine these factors with respect to The Walcott Quarry, Burgess Shale, Canada (510Ma) and the Fezouata Shale, Morocco (c. 475Ma). As the prototypical Burgess Shale-type locality, the Walcott Quarry, is usually used as a basis for understanding Cambrian community structure and early ecosystem evolution. The result of probabilistic modelling shows that the Walcott Quarry biota best preserves the endobenthic community whilst systematically under-representing the nekton/plankton. The reverse is true for the Fezouata biota, with under-representation of the endobenthos. Taken in concert with data from a bioturbation index for these sites, a new model of comparative taphonomy is developed based on sedimentary input timing with respect to organism mortality. These results suggest that during the Cambrian Explosion and Ordovician Radiation the most exceptional Fossils sites must still be calibrated against each other to understand the unfolding evolutionary events and ecosystem structures
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Mécanismes de préservation exceptionnelle dans le Lagerstätte des Fezouata (Ordovicien inférieur, Maroc)
HAL CCSD, 2020Co-Authors: Saleh FaridAbstract:The Fezouata Shale is the most diverse Lower Ordovician unit with exceptional Fossil Preservation. Fossils from this formation altered our understanding of early metazoan communities at the transition between the Cambrian Explosion and the Ordovician Radiation. The paleontology and the general sedimentological context of the Fezouata Shale are well established. However, little was done to understand the interaction between both, and studies regarding Fossil Preservation remain scarce. In this thesis, we investigate the general conditions and mechanisms responsible for soft-tissue Preservation in the Fezouata Shale. Comparing brachiopod, bivalve, and trilobite size fluctuations between sites allowed us to constrain burial rates in this formation. This permitted the discovery of a relative post-mortem burial tardiness in sites where exceptional Fossil Preservation occurred. Moreover, mineralogical investigations showed a correlation between particular chlorite phases (i.e. chamosite/berthierine) and preserved soft parts. This mineralogy may have slowed down oxic decay and its deposition was most probably due to periods with high seasonality. Furthermore, we hypothesized for the first time, a possible implication of biomolecules (i.e. ferritin) in the Preservation of soft parts. This, if confirmed, would resolve the observed discrepancies between the Fossil record preserving nervous systems to the exclusion to everything else, and decay experiments showing that nervous tissues are among the first structures to decay and disappear in laboratory conditions. Additionally, we show that metamorphism was not operational in the Fezouata Shale. However, modern weathering leached organic material from surface sediments and transformed pyrite into iron oxides. This finding infers that the original mode of Preservation of the Fezouata Shale comprises both carbonaceous compressions and accessory authigenic pyritization. The direct implication of this work was shown through a comparison of enigmatic patterns preserved in three groups of echinoderms. It appears that some of these patterns in eocrinoids and somasteroids do not reflect original anatomies and are Preservation artifacts. However, it is certain that the structures preserved in stylophorans are real, closing a long-standing debate on the affinity of this animal group. Finally, a general comparison between the Fezouata Shale and Cambrian Lagerstätten allowed us to decipher the implication of the suggested taphonomic pathway on Fossil Preservation. It appears that the Fezouata Shale mechanism for Preservation failed to preserve completely cellular organisms (e.g. chordates, ctenophores, medusoids) implying a possible underestimation of the original Fezouata Biota and confirming that the Cambrian Explosion and the Ordovician Radiation are one single episode of anatomical innovation. Thus, all these results have implications on understanding ecosystems, and evolution at the dawn of animal life and may contribute in the future to the development of a predictive approach for the discovery of exceptionally preserved biotasLa Formation des Fezouata a livré les assemblages à préservation exceptionnelle les plus diversifiés de l'Ordovicien inférieur. Les Fossiles de cette unité ont bouleversé notre compréhension des premières communautés animales à la transition entre l'explosion cambrienne et la diversification ordovicienne. La paléontologie et le contexte sédimentologique général de la Formation des Fezouata sont bien établis. Cependant, l'interaction entre les deux demeurait peu connue, et les études concernant la préservation des Fossiles étaient rares. Dans cette thèse, nous étudions les conditions et les mécanismes qui ont abouti de la préservation des tissus mous dans la Formation des Fezouata. La comparaison des fluctuations de taille des brachiopodes, des bivalves et des trilobites entre les différents sites nous a permis de contraindre le taux d'enfouissement dans cette formation. Cela nous a permis de mettre en évidence un enfouissement post-mortem relativement tardif dans les sites à préservation exceptionnelle de cette formation. De plus, les recherches minéralogiques ont montré une corrélation entre certains minéraux de chlorite (chamosite / berthierine) et les parties molles. Cette minéralogie peut avoir inhibé la dégradation oxique des tissus durant les périodes à forte saisonnalité. De plus, nous avons émis l'hypothèse d'une possible implication des biomolécules (ferritine) dans la préservation des parties molles. Ce scénario permettrait d'expliquer les écarts observés entre le registre Fossile préservant les systèmes nerveux à l'exclusion de tout le reste, et les expériences de dégradation montrant que les tissus nerveux sont parmi les premières structures à disparaître au laboratoire. De plus, nous montrons que l'influence du métamorphisme est négligeable dans la formation des Fezouata. Cependant, l’altération récente a lessivé la matière organique des sédiments de surface et transformé la pyrite en oxydes de fer. Cette découverte implique que le mode original de préservation des Fossiles de la Formation des Fezouata comprend à la fois les compressions carbonées et la pyritisation authigénique. Une conséquence directe de ce résultat a consisté en la comparaison de motifs énigmatiques préservés dans trois groupes d'échinodermes. Il apparaît ainsi que deux de ces motifs, observés chez les éocrinoïdes et les somastéroïdes, ne reflètent pas les anatomies originales et ne sont que des artefacts de préservation. Cependant, il est démontré que les structures préservées chez les stylophores sont bien réelles, mettant fin au débat sur l'affinité de ce groupe. Enfin, une comparaison générale entre la Formation des Fezouata et les Lagerstätten cambriens nous a permis de déterminer quelle a été l'influence de la voie taphonomique empruntée sur la préservation des Fossiles. Il semblerait que le mécanisme de préservation dans la Formation des Fezouata n'ait pas permis la conservation des organismes complètement cellulaires (par exemple, les chordés, les cténophores, les médusoïdes), ce qui impliquerait une sous-estimation de la biodiversité originelle dans les Fezouata et confirmerait que l'explosion cambrienne et le la radiation ordovicienne ne représentent qu'un seul et même épisode d'innovation anatomique. Ainsi, tous ces résultats ont des implications sur la compréhension des écosystèmes et de l'évolution à l'aube de la vie animale et pourraient contribuer ultérieurement au développement d'une approche prédictive permettant la découverte de nouveaux sites à préservation exceptionnell
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Mécanismes de préservation exceptionnelle dans le Lagerstätte des Fezouata (Ordovicien inférieur, Maroc)
2020Co-Authors: Saleh FaridAbstract:La Formation des Fezouata a livré les assemblages à préservation exceptionnelle les plus diversifiés de l'Ordovicien inférieur. Les Fossiles de cette unité ont bouleversé notre compréhension des premières communautés animales à la transition entre l'explosion cambrienne et la diversification ordovicienne. La paléontologie et le contexte sédimentologique général de la Formation des Fezouata sont bien établis. Cependant, l'interaction entre les deux demeurait peu connue, et les études concernant la préservation des Fossiles étaient rares. Dans cette thèse, nous étudions les conditions et les mécanismes qui ont abouti de la préservation des tissus mous dans la Formation des Fezouata. La comparaison des fluctuations de taille des brachiopodes, des bivalves et des trilobites entre les différents sites nous a permis de contraindre le taux d'enfouissement dans cette formation. Cela nous a permis de mettre en évidence un enfouissement post-mortem relativement tardif dans les sites à préservation exceptionnelle de cette formation. De plus, les recherches minéralogiques ont montré une corrélation entre certains minéraux de chlorite (chamosite / berthierine) et les parties molles. Cette minéralogie peut avoir inhibé la dégradation oxique des tissus durant les périodes à forte saisonnalité. De plus, nous avons émis l'hypothèse d'une possible implication des biomolécules (ferritine) dans la préservation des parties molles. Ce scénario permettrait d'expliquer les écarts observés entre le registre Fossile préservant les systèmes nerveux à l'exclusion de tout le reste, et les expériences de dégradation montrant que les tissus nerveux sont parmi les premières structures à disparaître au laboratoire. De plus, nous montrons que l'influence du métamorphisme est négligeable dans la formation des Fezouata. Cependant, l’altération récente a lessivé la matière organique des sédiments de surface et transformé la pyrite en oxydes de fer. Cette découverte implique que le mode original de préservation des Fossiles de la Formation des Fezouata comprend à la fois les compressions carbonées et la pyritisation authigénique. Une conséquence directe de ce résultat a consisté en la comparaison de motifs énigmatiques préservés dans trois groupes d'échinodermes. Il apparaît ainsi que deux de ces motifs, observés chez les éocrinoïdes et les somastéroïdes, ne reflètent pas les anatomies originales et ne sont que des artefacts de préservation. Cependant, il est démontré que les structures préservées chez les stylophores sont bien réelles, mettant fin au débat sur l'affinité de ce groupe. Enfin, une comparaison générale entre la Formation des Fezouata et les Lagerstätten cambriens nous a permis de déterminer quelle a été l'influence de la voie taphonomique empruntée sur la préservation des Fossiles. Il semblerait que le mécanisme de préservation dans la Formation des Fezouata n'ait pas permis la conservation des organismes complètement cellulaires (par exemple, les chordés, les cténophores, les médusoïdes), ce qui impliquerait une sous-estimation de la biodiversité originelle dans les Fezouata et confirmerait que l'explosion cambrienne et le la radiation ordovicienne ne représentent qu'un seul et même épisode d'innovation anatomique. Ainsi, tous ces résultats ont des implications sur la compréhension des écosystèmes et de l'évolution à l'aube de la vie animale et pourraient contribuer ultérieurement au développement d'une approche prédictive permettant la découverte de nouveaux sites à préservation exceptionnelleThe Fezouata Shale is the most diverse Lower Ordovician unit with exceptional Fossil Preservation. Fossils from this formation altered our understanding of early metazoan communities at the transition between the Cambrian Explosion and the Ordovician Radiation. The paleontology and the general sedimentological context of the Fezouata Shale are well established. However, little was done to understand the interaction between both, and studies regarding Fossil Preservation remain scarce. In this thesis, we investigate the general conditions and mechanisms responsible for soft-tissue Preservation in the Fezouata Shale. Comparing brachiopod, bivalve, and trilobite size fluctuations between sites allowed us to constrain burial rates in this formation. This permitted the discovery of a relative post-mortem burial tardiness in sites where exceptional Fossil Preservation occurred. Moreover, mineralogical investigations showed a correlation between particular chlorite phases (i.e. chamosite/berthierine) and preserved soft parts. This mineralogy may have slowed down oxic decay and its deposition was most probably due to periods with high seasonality. Furthermore, we hypothesized for the first time, a possible implication of biomolecules (i.e. ferritin) in the Preservation of soft parts. This, if confirmed, would resolve the observed discrepancies between the Fossil record preserving nervous systems to the exclusion to everything else, and decay experiments showing that nervous tissues are among the first structures to decay and disappear in laboratory conditions. Additionally, we show that metamorphism was not operational in the Fezouata Shale. However, modern weathering leached organic material from surface sediments and transformed pyrite into iron oxides. This finding infers that the original mode of Preservation of the Fezouata Shale comprises both carbonaceous compressions and accessory authigenic pyritization. The direct implication of this work was shown through a comparison of enigmatic patterns preserved in three groups of echinoderms. It appears that some of these patterns in eocrinoids and somasteroids do not reflect original anatomies and are Preservation artifacts. However, it is certain that the structures preserved in stylophorans are real, closing a long-standing debate on the affinity of this animal group. Finally, a general comparison between the Fezouata Shale and Cambrian Lagerstätten allowed us to decipher the implication of the suggested taphonomic pathway on Fossil Preservation. It appears that the Fezouata Shale mechanism for Preservation failed to preserve completely cellular organisms (e.g. chordates, ctenophores, medusoids) implying a possible underestimation of the original Fezouata Biota and confirming that the Cambrian Explosion and the Ordovician Radiation are one single episode of anatomical innovation. Thus, all these results have implications on understanding ecosystems, and evolution at the dawn of animal life and may contribute in the future to the development of a predictive approach for the discovery of exceptionally preserved biota
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Orbital control on exceptional Fossil Preservation
'Geological Society of America', 2019Co-Authors: Saleh Farid, Pittet Bernard, Perrillat Jean-philippe, Lefebvre BertrandAbstract:International audienceExceptional Fossil Preservation is defined by the Preservation of soft to lightly sclerotized organic tissues. The two most abundant types of soft-tissue Preservation are carbonaceous compressions and replicates in authigenic minerals. In the geological record, exceptionally preserved soft Fossils are rare and generally limited to only a few stratigraphic intervals. In the Fezouata Shale (Lower Ordovician, southern Morocco), we found that deposits yielding pyritized soft tissues contain iron-rich silicate minerals. These minerals played a crucial role in inhibiting the decay of dead individuals and are comparable to those found in formations yielding carbonaceous soft parts around the world. Furthermore, we found that iron-rich minerals show a cyclic pattern of occurrence (of ~100 k.y. periodicity) implicating a short-period eccentricity control on iron availability through the general oceanic and atmospheric circulations. Our results identify, for the first time, an external climate forcing on exceptional Preservation and show that orbital forcing may be a level-selective parameter responsible for the discontinuous occurrence of horizons preserving soft parts around the world
Dario De Franceschi - One of the best experts on this subject based on the ideXlab platform.
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First record of an Icacinaceae Miers Fossil flower from Le Quesnoy (Ypresian, France) amber
Scientific Reports, 2017Co-Authors: Cedric Del Rio, Thomas Haevermans, Dario De FranceschiAbstract:Flowers embedded in amber are rare. Only about 70 flowers or inflorescences have been described among which only one lamiid is known. Nevertheless, these Fossils are important to our understanding of evolutionary process and past diversity due to the exceptional Preservation of fragile structures not normally preserved. In this work, a new flower named Icacinanthium tainiaphorum sp. nov. from Le Quesnoy (Houdancourt, Oise, France) is described. Our phylogenetic analysis with extant species suggests that the affinity of this flower lies with the family Icacinaceae, close to Natsiatum or Hosiea. The Fossil shows a combination of features unknown in extant Icacinaceae and we thus propose the description of a new Fossil genus. It reveals a previously unknown diversity in the family and demonstrates the complementarity of different types of Fossil Preservation for a better understanding of past floral diversity.
Cedric Del Rio - One of the best experts on this subject based on the ideXlab platform.
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First record of an Icacinaceae Miers Fossil flower from Le Quesnoy (Ypresian, France) amber
Scientific Reports, 2017Co-Authors: Cedric Del Rio, Thomas Haevermans, Dario De FranceschiAbstract:Flowers embedded in amber are rare. Only about 70 flowers or inflorescences have been described among which only one lamiid is known. Nevertheless, these Fossils are important to our understanding of evolutionary process and past diversity due to the exceptional Preservation of fragile structures not normally preserved. In this work, a new flower named Icacinanthium tainiaphorum sp. nov. from Le Quesnoy (Houdancourt, Oise, France) is described. Our phylogenetic analysis with extant species suggests that the affinity of this flower lies with the family Icacinaceae, close to Natsiatum or Hosiea. The Fossil shows a combination of features unknown in extant Icacinaceae and we thus propose the description of a new Fossil genus. It reveals a previously unknown diversity in the family and demonstrates the complementarity of different types of Fossil Preservation for a better understanding of past floral diversity.
Glenn A Brock - One of the best experts on this subject based on the ideXlab platform.
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facies phosphate and Fossil Preservation potential across a lower cambrian carbonate shelf arrowie basin south australia
Palaeogeography Palaeoclimatology Palaeoecology, 2019Co-Authors: Sarah M Jacquet, Marissa J Betts, John Warren Huntley, Glenn A BrockAbstract:Abstract The effects of sedimentological, depositional and taphonomic processes on Preservation potential of Cambrian small shelly Fossils (SSF) have important implications for their utility in biostratigraphy and high-resolution correlation. To investigate the effects of these processes on Fossil occurrence, detailed microfacies analysis, biostratigraphic data, and multivariate analyses are integrated from an exemplar stratigraphic section intersecting a suite of lower Cambrian carbonate palaeoenvironments in the northern Flinders Ranges, South Australia. The succession deepens upsection, across a low-gradient shallow-marine shelf. Six depositional Facies Sequences are identified ranging from protected (FS1) and open (FS2) shelf/lagoonal systems, high-energy inner ramp shoal complex (FS3), mid-shelf (FS4), mid- to outer-shelf (FS5) and outer-shelf (FS6) environments. Non-metric multi-dimensional scaling ordination and two-way cluster analysis reveal an underlying bathymetric gradient as the main control on the distribution of SSFs. Unlike groups that produced primary organophosphatic biominerals, taxa that built calcareous skeletons are more taphonomically-controlled, which is further exacerbated by sampling and processing biases. A strong facies association with condensed and reworked horizons suggests the stratigraphic occurrence of calcareous groups reflects conditions conducive to Preservation (phosphogenesis and phosphatization) rather than true stratigraphic ranges. Consequently, organophosphatic taxa should take precedence in the erection of biostratigraphic zones for subdivision of lower Cambrian successions.
Lefebvre Bertrand - One of the best experts on this subject based on the ideXlab platform.
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A novel tool to untangle the ecology and Fossil Preservation knot in exceptionally preserved biotas
'Elsevier BV', 2022Co-Authors: Saleh Farid, Pittet Bernard, Lefebvre Bertrand, Ma Xiaoya, Bath-enright, Orla G., Daley, Allison C., Vite Antoine, Mángano M. Gabriela, Buatois, Luis A., Antcliffe, Jonathan B.Abstract:Understanding the functioning of extinct ecosystems is a complicated knot of ecological, evolutionary, and Preservational strands that must be untangled. For instance, anatomical and behavioral differences can profoundly alter Fossilization pathways. This is particularly true in exceptionally preserved soft-bodied biotas that record the earliest phases of animal evolution during the Cambrian Explosion and the Ordovician Radiation. Herein, a novel method of data partitioning based on probabilistic modelling is developed to examine these processes for the Walcott Quarry, Burgess Shale, Canada (510Ma), and the Fezouata Shale, Morocco (c. 475Ma). The modelling shows that the mechanism for soft-tissue Preservation in the Walcott Quarry is ecologically selective, favoring the endobenthos. This is not found in the Fezouata Shale. Taken in concert with bioturbation data, a new model of comparative Preservation is developed based on sedimentary flow dynamics. This suggests that during the Cambrian Explosion and Ordovician Radiation the most exceptional Fossils sites must still be calibrated against each other to understand the unfolding evolutionary events and the ecological structuring of ancient animal communities
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Untangling the ecology and Fossil Preservation knot for Paleozoic Biotas
'Geological Society of America', 2020Co-Authors: Saleh Farid, Bath Enright Orla, Daley Allison, Pittet Bernard, Lefebvre Bertrand, Antcliffe JonathanAbstract:International audienceFossil deposits are a tangle of multiple signals that make understanding the functioning of past ecosystems a complicated and fraught process. The main difficulty is whether differences between Fossil sites show an evolutionary or ecological signal, or are influenced by Fossil Preservation. These processes are not independent, as anatomical or behavioral differences can alter Preservational pathways. It is particularly important to untangle these interacting processes when examining the animal communities of the Cambrian Explosion and Ordovician Radiation, where exceptional Preservation of soft tissues provides relatively complete assemblage data. A novel method of data partitioning based on probabilistic modelling is used to examine these factors with respect to The Walcott Quarry, Burgess Shale, Canada (510Ma) and the Fezouata Shale, Morocco (c. 475Ma). As the prototypical Burgess Shale-type locality, the Walcott Quarry, is usually used as a basis for understanding Cambrian community structure and early ecosystem evolution. The result of probabilistic modelling shows that the Walcott Quarry biota best preserves the endobenthic community whilst systematically under-representing the nekton/plankton. The reverse is true for the Fezouata biota, with under-representation of the endobenthos. Taken in concert with data from a bioturbation index for these sites, a new model of comparative taphonomy is developed based on sedimentary input timing with respect to organism mortality. These results suggest that during the Cambrian Explosion and Ordovician Radiation the most exceptional Fossils sites must still be calibrated against each other to understand the unfolding evolutionary events and ecosystem structures
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Orbital control on exceptional Fossil Preservation
'Geological Society of America', 2019Co-Authors: Saleh Farid, Pittet Bernard, Perrillat Jean-philippe, Lefebvre BertrandAbstract:International audienceExceptional Fossil Preservation is defined by the Preservation of soft to lightly sclerotized organic tissues. The two most abundant types of soft-tissue Preservation are carbonaceous compressions and replicates in authigenic minerals. In the geological record, exceptionally preserved soft Fossils are rare and generally limited to only a few stratigraphic intervals. In the Fezouata Shale (Lower Ordovician, southern Morocco), we found that deposits yielding pyritized soft tissues contain iron-rich silicate minerals. These minerals played a crucial role in inhibiting the decay of dead individuals and are comparable to those found in formations yielding carbonaceous soft parts around the world. Furthermore, we found that iron-rich minerals show a cyclic pattern of occurrence (of ~100 k.y. periodicity) implicating a short-period eccentricity control on iron availability through the general oceanic and atmospheric circulations. Our results identify, for the first time, an external climate forcing on exceptional Preservation and show that orbital forcing may be a level-selective parameter responsible for the discontinuous occurrence of horizons preserving soft parts around the world