S. Rowland, T. Whitworth, Michele Jones, J. Dooley, Eric Chameroy, T. Gordon
Abstract: We report the occurrence of abundant dipteran puparia of Phormia regina, the black blow fly, in association with an early historic-age bison skeleton excavated near Carson City, Nevada. Cut marks on some of the bones indicate that the bison was butchered and probably skinned by humans. Radiocarbon dating provides two possible age intervals for the death of the bison: (1) latest seventeenth to early eighteenth century or (2) early nineteenth to early twentieth century; we consider the more recent age to be more plausible. The purpose of this study is to explore how the presence of puparia of this well-studied, necrophagous fly species can be used to help constrain the season of death and inform the interpretation of the taphonomic history of the bison. The life cycle of P. regina requires a minimum of 8.8 days within a temperature range of 14°C to 35°C, so the bison carcass must have been exposed to the air for at least that long within that temperature range. However, of the thousands of recovered puparia, 35% remain closed and did not produce adult flies; of this cohort, only a tiny percentage exhibit small exit holes attributable to parasitoid wasps. Cold temperatures, and not parasitoid wasps, are the most probable cause of the high pupal mortality. Climate data for the region, along with P. regina temperature constraints and streamflow and flooding records for the Carson River watershed, indicate that the bison died and was colonized by black blow flies in the spring, when night-time temperatures were low. A short time later the skinned and butchered skeleton was buried by floodplain sediments. Blow fly puparia can contribute useful information for the taphonomic analysis of vertebrate fossil sites.
{"title":"THE BISON AND THE BLOW FLY: USING PUPARIA OF THE BLACK BLOW FLY (PHORMIA REGINA: DIPTERA, CALLIPHORIDAE) TO CONSTRAIN THE SEASON OF DEATH AND TAPHONOMIC HISTORY OF AN EARLY HISTORIC-AGE BISON, CARSON CITY, NEVADA, USA","authors":"S. Rowland, T. Whitworth, Michele Jones, J. Dooley, Eric Chameroy, T. Gordon","doi":"10.2110/palo.2021.039","DOIUrl":"https://doi.org/10.2110/palo.2021.039","url":null,"abstract":"Abstract: We report the occurrence of abundant dipteran puparia of Phormia regina, the black blow fly, in association with an early historic-age bison skeleton excavated near Carson City, Nevada. Cut marks on some of the bones indicate that the bison was butchered and probably skinned by humans. Radiocarbon dating provides two possible age intervals for the death of the bison: (1) latest seventeenth to early eighteenth century or (2) early nineteenth to early twentieth century; we consider the more recent age to be more plausible. The purpose of this study is to explore how the presence of puparia of this well-studied, necrophagous fly species can be used to help constrain the season of death and inform the interpretation of the taphonomic history of the bison. The life cycle of P. regina requires a minimum of 8.8 days within a temperature range of 14°C to 35°C, so the bison carcass must have been exposed to the air for at least that long within that temperature range. However, of the thousands of recovered puparia, 35% remain closed and did not produce adult flies; of this cohort, only a tiny percentage exhibit small exit holes attributable to parasitoid wasps. Cold temperatures, and not parasitoid wasps, are the most probable cause of the high pupal mortality. Climate data for the region, along with P. regina temperature constraints and streamflow and flooding records for the Carson River watershed, indicate that the bison died and was colonized by black blow flies in the spring, when night-time temperatures were low. A short time later the skinned and butchered skeleton was buried by floodplain sediments. Blow fly puparia can contribute useful information for the taphonomic analysis of vertebrate fossil sites.","PeriodicalId":54647,"journal":{"name":"Palaios","volume":"38 1","pages":"22 - 30"},"PeriodicalIF":1.6,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45343179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT: The Bogda Mountains, Xianjiang Uygur Autonomous Region, western China, expose an uppermost Permian–Lower Triassic succession of fully continental strata deposited across three graben (half graben) structures in the mid-paleolatitudes of Pangea. A cyclostratigraphy scheme developed for the succession is subdivided into three low-order cycles (Wutonggou, Jiucaiyuan, Shaofanggou). Low-order cycles are partitioned into 1838 high-order cycles based on repetitive environmental changes, and their plant taphonomic character is assessed in > 4700 m of high-resolution, measured sections distributed across ∼ 100 km. Four taphonomic assemblages are represented by: permineralized wood (both autochthonous and allochthonous), megafloral adpressions (?parautochthonous and allochthonous) identifiable to systematic affinity, unidentifiable (allochthonous) phytoclasts concentrated or disseminated on bedding, and (autochthonous) rooting structures of various configurations (carbon films to rhizoconcretions). Their temporal and spatial occurrences vary across the study area and are dependent on the array of depositional environments exposed in any particular locality. Similar to paleobotanical results in other fully continental basins, megafloral elements are rarely encountered. Both wood (erect permineralized stumps and prostrate logs) and adpressions are found in < 2% of meandering river and limnic cycles, where sediment accumulated under semi-arid to humid conditions. The absence of such assemblages in river-and-lake deposits is more likely related to physical or geographical factors than it is to an absence of organic-matter contribution. With such a low frequency, no predictable pattern or trend to their occurrence can be determined. This is also true for any horizon in which rooting structures are preserved, although paleosols occur in all or parts of high-order cycles developed under arid to humid conditions. Physical rooting structures are encountered in only 23% of these and are not preserved equally across space and time. Allochthonous phytoclasts are the most common taphonomic assemblage, preserved in association with micaceous minerals on bedding in fine-grained lithofacies. The consistency of phytoclast assemblages throughout the succession is empirical evidence for the presence of riparian vegetation during a time when models propose the catastrophic demise of land plants, and does not support an interpretation of vegetational demise followed by long-term recovery across the crisis interval in this basin. These mesofossil and microfossil (palynological) assemblages offer the best opportunity to understand the effects of the crisis on the base of terrestrial ecosystems.
{"title":"THE TAPHONOMIC CHARACTER, OCCURRENCE, AND PERSISTENCE OF UPPER PERMIAN–LOWER TRIASSIC PLANT ASSEMBLAGES IN THE MID-PALEOLATITUDES, BOGDA MOUNTAINS, WESTERN CHINA","authors":"R. Gastaldo, Mingli Wan, Wan Yang","doi":"10.2110/palo.2022.025","DOIUrl":"https://doi.org/10.2110/palo.2022.025","url":null,"abstract":"ABSTRACT: The Bogda Mountains, Xianjiang Uygur Autonomous Region, western China, expose an uppermost Permian–Lower Triassic succession of fully continental strata deposited across three graben (half graben) structures in the mid-paleolatitudes of Pangea. A cyclostratigraphy scheme developed for the succession is subdivided into three low-order cycles (Wutonggou, Jiucaiyuan, Shaofanggou). Low-order cycles are partitioned into 1838 high-order cycles based on repetitive environmental changes, and their plant taphonomic character is assessed in > 4700 m of high-resolution, measured sections distributed across ∼ 100 km. Four taphonomic assemblages are represented by: permineralized wood (both autochthonous and allochthonous), megafloral adpressions (?parautochthonous and allochthonous) identifiable to systematic affinity, unidentifiable (allochthonous) phytoclasts concentrated or disseminated on bedding, and (autochthonous) rooting structures of various configurations (carbon films to rhizoconcretions). Their temporal and spatial occurrences vary across the study area and are dependent on the array of depositional environments exposed in any particular locality. Similar to paleobotanical results in other fully continental basins, megafloral elements are rarely encountered. Both wood (erect permineralized stumps and prostrate logs) and adpressions are found in < 2% of meandering river and limnic cycles, where sediment accumulated under semi-arid to humid conditions. The absence of such assemblages in river-and-lake deposits is more likely related to physical or geographical factors than it is to an absence of organic-matter contribution. With such a low frequency, no predictable pattern or trend to their occurrence can be determined. This is also true for any horizon in which rooting structures are preserved, although paleosols occur in all or parts of high-order cycles developed under arid to humid conditions. Physical rooting structures are encountered in only 23% of these and are not preserved equally across space and time. Allochthonous phytoclasts are the most common taphonomic assemblage, preserved in association with micaceous minerals on bedding in fine-grained lithofacies. The consistency of phytoclast assemblages throughout the succession is empirical evidence for the presence of riparian vegetation during a time when models propose the catastrophic demise of land plants, and does not support an interpretation of vegetational demise followed by long-term recovery across the crisis interval in this basin. These mesofossil and microfossil (palynological) assemblages offer the best opportunity to understand the effects of the crisis on the base of terrestrial ecosystems.","PeriodicalId":54647,"journal":{"name":"Palaios","volume":"38 1","pages":"1 - 21"},"PeriodicalIF":1.6,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48258321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Lazer, Ian P. Stout, E. Simpson, M. Wizevich, Abigal M. Keebler, Grace Hetrick
Abstract: Dinosaur eggshell fragments, from the Upper Jurassic Brushy Basin Member of the Morrison Formation, Utah, were examined using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive Spectroscopy, and Raman Spectroscopy. Analyses revealed that the mammillary tips on the shell interior contain carbonaceous residue. Comparison under the FESEM of these shells with modern bird shells, including some samples heated to diagenetic temperatures, indicate that the residue is degraded organic compounds (DOC). Bird egg membrane is composed of interlaced collagen fibers. Features observed on, and common to, modern bird and dinosaur egg fragments include: (1) irregular-shaped calcium carbonate grains “floating” in an organic matrix; (2) three-dimensional organic fiber matrix; (3) external calcium carbonate molds of fibers in the mammillary bodies; and in heated specimens, (4) carbonaceous residue with ovate to circular pores. However, unlike birds' eggs, the dinosaur eggs contain a calcium carbonate tube around fibrous organic material that emerges from the tube and spreads laterally in a ‘puddle-like’ deposit. The sizes of circular organic matrix pores of the dinosaur egg fragments are significantly smaller than those in the bird shells. Gallus gallus domesticus eggshell membranes heated to diagenetic temperatures resulted in alteration of collagen fibers to gel-like substances. The organic matrix with ovate to circular pore openings and the puddle-like deposits in the dinosaur egg fragments are interpreted as the product of membrane thermal diagenesis. The recognition of carbonaceous residue of the shell membrane on dinosaur shell fragments opens newfound opportunities to explore DOC associated with fragmental dinosaur eggs.
{"title":"PRESERVED MEMBRANE ON DINOSAUR EGGSHELL FRAGMENTS, UPPER JURASSIC MORRISON FORMATION, EASTERN UTAH","authors":"K. Lazer, Ian P. Stout, E. Simpson, M. Wizevich, Abigal M. Keebler, Grace Hetrick","doi":"10.2110/palo.2022.002","DOIUrl":"https://doi.org/10.2110/palo.2022.002","url":null,"abstract":"Abstract: Dinosaur eggshell fragments, from the Upper Jurassic Brushy Basin Member of the Morrison Formation, Utah, were examined using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive Spectroscopy, and Raman Spectroscopy. Analyses revealed that the mammillary tips on the shell interior contain carbonaceous residue. Comparison under the FESEM of these shells with modern bird shells, including some samples heated to diagenetic temperatures, indicate that the residue is degraded organic compounds (DOC). Bird egg membrane is composed of interlaced collagen fibers. Features observed on, and common to, modern bird and dinosaur egg fragments include: (1) irregular-shaped calcium carbonate grains “floating” in an organic matrix; (2) three-dimensional organic fiber matrix; (3) external calcium carbonate molds of fibers in the mammillary bodies; and in heated specimens, (4) carbonaceous residue with ovate to circular pores. However, unlike birds' eggs, the dinosaur eggs contain a calcium carbonate tube around fibrous organic material that emerges from the tube and spreads laterally in a ‘puddle-like’ deposit. The sizes of circular organic matrix pores of the dinosaur egg fragments are significantly smaller than those in the bird shells. Gallus gallus domesticus eggshell membranes heated to diagenetic temperatures resulted in alteration of collagen fibers to gel-like substances. The organic matrix with ovate to circular pore openings and the puddle-like deposits in the dinosaur egg fragments are interpreted as the product of membrane thermal diagenesis. The recognition of carbonaceous residue of the shell membrane on dinosaur shell fragments opens newfound opportunities to explore DOC associated with fragmental dinosaur eggs.","PeriodicalId":54647,"journal":{"name":"Palaios","volume":"38 1","pages":"43 - 55"},"PeriodicalIF":1.6,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46784448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract: Bioturbating activities have played a vital role in shaping the marine ecosystem throughout metazoan history, influencing the abundance and preservation potential of body fossil-producing taxa and driving major environmental and geochemical changes. The earliest trace making behaviors arose during the late Ediacaran Period (∼ 560–541 Ma), disrupting the substrate previously occupied by dominantly sessile organisms. Simple dwelling and grazing behaviors exploited the organic-rich matgrounds, expanding into the underutilized microbial mat ecosystem. In the western United States, trace assemblages from Ediacaran–Cambrian boundary-spanning deposits document a thriving trace-maker ecosystem. One boundary-spanning deposit in this region, the lower member of the Wood Canyon Formation, crops out along the California-Nevada boundary and contains both trace and body fossil assemblages. The Chicago Pass section of the lower Wood Canyon Formation contains a suite of dominantly simple Ediacaran traces, which become commonplace in the upper part of the stratigraphic section, documenting the onset of prevalent trace-making behaviors in this region. While traces have been previously described from this locality, the addition of the complex trace Lamonte trevallis and quantification of trace fossil density of simple Ediacaran traces provides a more comprehensive ichnological view of the Chicago Pass section. Although Chicago Pass does not yield abundant tubicolous body fossils, as are found elsewhere in the region, the low diversity ichnoassemblages document both burgeoning surficial trace making groups and mat-targeted mining in the latest Ediacaran. The behaviors present at Chicago Pass are similar to those of the Dengying Formation in South China, and highlight the need for petrographic-based trace fossil studies. Additionally, studies of Nama Group trace fossils of the same age from Namibia report higher diversity and complexity in trace-making activities than what has been observed at Chicago Pass, but with similar, low Ediacara biota body fossil diversity. If Ediacara biota diversity is anticorrelated with trace-making behaviors, Chicago Pass represents a low-complexity end-member of the same phenomenon observed in Namibia. The effect of surface sediment disruption on the sessile Ediacaran communities may have been decoupled from complexity of the traces, more so influenced by the presence of general trace-making behaviors in aggregate, including simple traces.
{"title":"THE ROLE OF SURFICIAL BIOTURBATION IN THE LATEST EDIACARAN: A QUANTITATIVE ANALYSIS OF TRACE FOSSIL INTENSITY IN THE TERMINAL EDIACARAN–LOWER CAMBRIAN OF CALIFORNIA","authors":"Gretchen R. O'Neil, L. Tackett, M. Meyer","doi":"10.2110/palo.2021.050","DOIUrl":"https://doi.org/10.2110/palo.2021.050","url":null,"abstract":"Abstract: Bioturbating activities have played a vital role in shaping the marine ecosystem throughout metazoan history, influencing the abundance and preservation potential of body fossil-producing taxa and driving major environmental and geochemical changes. The earliest trace making behaviors arose during the late Ediacaran Period (∼ 560–541 Ma), disrupting the substrate previously occupied by dominantly sessile organisms. Simple dwelling and grazing behaviors exploited the organic-rich matgrounds, expanding into the underutilized microbial mat ecosystem. In the western United States, trace assemblages from Ediacaran–Cambrian boundary-spanning deposits document a thriving trace-maker ecosystem. One boundary-spanning deposit in this region, the lower member of the Wood Canyon Formation, crops out along the California-Nevada boundary and contains both trace and body fossil assemblages. The Chicago Pass section of the lower Wood Canyon Formation contains a suite of dominantly simple Ediacaran traces, which become commonplace in the upper part of the stratigraphic section, documenting the onset of prevalent trace-making behaviors in this region. While traces have been previously described from this locality, the addition of the complex trace Lamonte trevallis and quantification of trace fossil density of simple Ediacaran traces provides a more comprehensive ichnological view of the Chicago Pass section. Although Chicago Pass does not yield abundant tubicolous body fossils, as are found elsewhere in the region, the low diversity ichnoassemblages document both burgeoning surficial trace making groups and mat-targeted mining in the latest Ediacaran. The behaviors present at Chicago Pass are similar to those of the Dengying Formation in South China, and highlight the need for petrographic-based trace fossil studies. Additionally, studies of Nama Group trace fossils of the same age from Namibia report higher diversity and complexity in trace-making activities than what has been observed at Chicago Pass, but with similar, low Ediacara biota body fossil diversity. If Ediacara biota diversity is anticorrelated with trace-making behaviors, Chicago Pass represents a low-complexity end-member of the same phenomenon observed in Namibia. The effect of surface sediment disruption on the sessile Ediacaran communities may have been decoupled from complexity of the traces, more so influenced by the presence of general trace-making behaviors in aggregate, including simple traces.","PeriodicalId":54647,"journal":{"name":"Palaios","volume":"37 1","pages":"703 - 717"},"PeriodicalIF":1.6,"publicationDate":"2022-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45661381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. De Baets, E. Jarochowska, Stella Zora Buchwald, C. Klug, D. Korn
Abstract: Body-size distributions of organisms across environments in space and time are a powerful source of information on ecological and evolutionary processes. However, most studies only focus on selected parameters of size distributions (e.g., central tendency or extremes) and rarely take into account entire distributions and how they are affected by the collection style and facies. Here we analyze the impact of facies, region, taxonomy, and collection style over size distributions using diameter as a proxy of Late Devonian ammonoids in their entirety using non-metric multidimensional scaling and PERMANOVA based on Kolmogorov distance. The effects are then compared with effects on mean sizes. In all analyses, lithology was the dominant effect, with sizes greater by 59% in marls and by 33% in limestones, as compared to black shales. The effect of complete sampling style was a decrease in size by 11%. Kurtosis was an important parameter differentiating size distributions, with platykurtic distributions in marls and leptokurtic distributions in limestones, suggesting that this parameter may reflect different degrees of time averaging. Most size distributions were positively skewed, but most strongly in marls. Complete sampling led to skewness values close to zero (symmetrical distributions) and high kurtosis. Samples from higher paleolatitudes were on average smaller, but contained outliers with the largest sizes, highlighting the need to analyze entire distributions. Lithology and collection differences need to be accounted for when evaluating size differences across space (polar gigantism) and time (Lilliput effect). Similarly, differences in facies may affect species determination.
{"title":"LITHOLOGY CONTROLS AMMONOID SIZE DISTRIBUTIONS","authors":"K. De Baets, E. Jarochowska, Stella Zora Buchwald, C. Klug, D. Korn","doi":"10.2110/palo.2021.063","DOIUrl":"https://doi.org/10.2110/palo.2021.063","url":null,"abstract":"Abstract: Body-size distributions of organisms across environments in space and time are a powerful source of information on ecological and evolutionary processes. However, most studies only focus on selected parameters of size distributions (e.g., central tendency or extremes) and rarely take into account entire distributions and how they are affected by the collection style and facies. Here we analyze the impact of facies, region, taxonomy, and collection style over size distributions using diameter as a proxy of Late Devonian ammonoids in their entirety using non-metric multidimensional scaling and PERMANOVA based on Kolmogorov distance. The effects are then compared with effects on mean sizes. In all analyses, lithology was the dominant effect, with sizes greater by 59% in marls and by 33% in limestones, as compared to black shales. The effect of complete sampling style was a decrease in size by 11%. Kurtosis was an important parameter differentiating size distributions, with platykurtic distributions in marls and leptokurtic distributions in limestones, suggesting that this parameter may reflect different degrees of time averaging. Most size distributions were positively skewed, but most strongly in marls. Complete sampling led to skewness values close to zero (symmetrical distributions) and high kurtosis. Samples from higher paleolatitudes were on average smaller, but contained outliers with the largest sizes, highlighting the need to analyze entire distributions. Lithology and collection differences need to be accounted for when evaluating size differences across space (polar gigantism) and time (Lilliput effect). Similarly, differences in facies may affect species determination.","PeriodicalId":54647,"journal":{"name":"Palaios","volume":"37 1","pages":"744 - 754"},"PeriodicalIF":1.6,"publicationDate":"2022-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41317718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract: Throughout the history of life on Earth, sedimentary environments have placed controls on the trajectory of evolutionary innovations. To survive and thrive in newly colonized sedimentary environments, organisms have needed to develop novel behaviors: often evidenced in the rock record as architectural innovation and diversification in trace fossil morphology. This study focuses on ichnological diversification as a response to challenges presented by different sediment grain sizes during the late Silurian to Early Devonian colonization of the continents by invertebrate life. The ichnodiversity and ichnodisparity from this interval reveal details of the biological response to newly adopted sedimentary and environmental conditions. Characteristics of ichnofaunas from terrestrial and emergent settings are compared across the Silurian-Devonian boundary, within both sand and mud dominated successions, to identify differences associated with different substrate compositions. Two trends are revealed: 1) Successions dominated by mudrock contain a lower ichnodiversity than sandstone-dominated successions of similar age, potentially due to the different challenges associated with burrowing in cohesive versus non-cohesive media. Alternatively, this could be due to preference of the tracemakers for the broader environmental conditions that lead to sand or mud deposition. 2) The maximum size of trace fossils within a given formation is larger in sandstone dominated strata than in mudrock dominated strata. Together, these suggest that the availability of substrates with different grain sizes was one factor determining the constitution of early animal communities and behavioral styles during the colonization of the continents.
{"title":"GRAIN-SIZE CONTROLS ON THE SILURO-DEVONIAN COLONIZATION OF NON-MARINE SUBSTRATES BY INFAUNAL INVERTEBRATES","authors":"Anthony P. Shillito, N. Davies","doi":"10.2110/palo.2021.069","DOIUrl":"https://doi.org/10.2110/palo.2021.069","url":null,"abstract":"Abstract: Throughout the history of life on Earth, sedimentary environments have placed controls on the trajectory of evolutionary innovations. To survive and thrive in newly colonized sedimentary environments, organisms have needed to develop novel behaviors: often evidenced in the rock record as architectural innovation and diversification in trace fossil morphology. This study focuses on ichnological diversification as a response to challenges presented by different sediment grain sizes during the late Silurian to Early Devonian colonization of the continents by invertebrate life. The ichnodiversity and ichnodisparity from this interval reveal details of the biological response to newly adopted sedimentary and environmental conditions. Characteristics of ichnofaunas from terrestrial and emergent settings are compared across the Silurian-Devonian boundary, within both sand and mud dominated successions, to identify differences associated with different substrate compositions. Two trends are revealed: 1) Successions dominated by mudrock contain a lower ichnodiversity than sandstone-dominated successions of similar age, potentially due to the different challenges associated with burrowing in cohesive versus non-cohesive media. Alternatively, this could be due to preference of the tracemakers for the broader environmental conditions that lead to sand or mud deposition. 2) The maximum size of trace fossils within a given formation is larger in sandstone dominated strata than in mudrock dominated strata. Together, these suggest that the availability of substrates with different grain sizes was one factor determining the constitution of early animal communities and behavioral styles during the colonization of the continents.","PeriodicalId":54647,"journal":{"name":"Palaios","volume":"37 1","pages":"731 - 743"},"PeriodicalIF":1.6,"publicationDate":"2022-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44222198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Brittany Laing, L. Buatois, M. Mángano, N. Minter, L. Strotz, G. Narbonne, G. Brock
ABSTRACT: Bioturbating organisms can dramatically alter the physical, chemical, and hydrological properties of the sediment and promote or hinder microbial growth. They are a classic example of “ecosystem engineers” as they alter the availability of resources to other species. Multiple evolutionary hypotheses evoke bioturbation as a possible driver for historical ecological change. To test these hypotheses, researchers need reliable and reproducible methods for estimating the impact of bioturbation in ancient environments. Early efforts to record and compare this impact through geologic time focused on the degree of bioturbation (e.g., bioturbation indices), the depth of bioturbation (e.g., bioturbation depth), or the structure of the infaunal community (e.g., tiering, ecospace utilization). Models which combine several parameters (e.g., functional groups, tier, motility, sediment interaction style) have been proposed and applied across the geological timescale in recent years. Here, we review all models that characterize the impact of bioturbators on the sedimentary environment (i.e., ‘ecosystem engineering’), in both modern and fossil sediments, and propose several questions. What are the assumptions of each approach? Are the current models appropriate for the metrics they wish to measure? Are they robust and reproducible? Our review highlights the nature of the sedimentary environment as an important parameter when characterizing ecosystem engineering intensity and outlines considerations for a best-practice model to measure the impact of bioturbation in geological datasets.
{"title":"BIOTURBATORS AS ECOSYSTEM ENGINEERS: ASSESSING CURRENT MODELS","authors":"Brittany Laing, L. Buatois, M. Mángano, N. Minter, L. Strotz, G. Narbonne, G. Brock","doi":"10.2110/palo.2022.012","DOIUrl":"https://doi.org/10.2110/palo.2022.012","url":null,"abstract":"ABSTRACT: Bioturbating organisms can dramatically alter the physical, chemical, and hydrological properties of the sediment and promote or hinder microbial growth. They are a classic example of “ecosystem engineers” as they alter the availability of resources to other species. Multiple evolutionary hypotheses evoke bioturbation as a possible driver for historical ecological change. To test these hypotheses, researchers need reliable and reproducible methods for estimating the impact of bioturbation in ancient environments. Early efforts to record and compare this impact through geologic time focused on the degree of bioturbation (e.g., bioturbation indices), the depth of bioturbation (e.g., bioturbation depth), or the structure of the infaunal community (e.g., tiering, ecospace utilization). Models which combine several parameters (e.g., functional groups, tier, motility, sediment interaction style) have been proposed and applied across the geological timescale in recent years. Here, we review all models that characterize the impact of bioturbators on the sedimentary environment (i.e., ‘ecosystem engineering’), in both modern and fossil sediments, and propose several questions. What are the assumptions of each approach? Are the current models appropriate for the metrics they wish to measure? Are they robust and reproducible? Our review highlights the nature of the sedimentary environment as an important parameter when characterizing ecosystem engineering intensity and outlines considerations for a best-practice model to measure the impact of bioturbation in geological datasets.","PeriodicalId":54647,"journal":{"name":"Palaios","volume":"37 1","pages":"718 - 730"},"PeriodicalIF":1.6,"publicationDate":"2022-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48602525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anthony P. Shillito, N. Davies, W. McMahon, Ben J. Slater
This thematic set is the second of a pair of volumes delving into the co-evolution of life and sedimentary environments in deep time. Whilst the full gamut of life-sediment interactions is far too vast to cover in its entirety, across both volumes this set provides examples of how different organisms have interacted with sedimentary environments across the entirety of the Phanerozoic. The first thematic set of this pair focused on plant-sediment interactions from the Carboniferous to the Pliocene (Davies et al. 2022), whereas this second set has a loose running theme of ‘animals’; documenting examples of interactions between metazoans and the environments that they occupied. In the introduction to first thematic set,
{"title":"DEEP TIME BIOGEOMORPHOLOGY 2: ANIMALS AS ANCIENT ECOSYSTEM ENGINEERS","authors":"Anthony P. Shillito, N. Davies, W. McMahon, Ben J. Slater","doi":"10.2110/palo.2022.053","DOIUrl":"https://doi.org/10.2110/palo.2022.053","url":null,"abstract":"This thematic set is the second of a pair of volumes delving into the co-evolution of life and sedimentary environments in deep time. Whilst the full gamut of life-sediment interactions is far too vast to cover in its entirety, across both volumes this set provides examples of how different organisms have interacted with sedimentary environments across the entirety of the Phanerozoic. The first thematic set of this pair focused on plant-sediment interactions from the Carboniferous to the Pliocene (Davies et al. 2022), whereas this second set has a loose running theme of ‘animals’; documenting examples of interactions between metazoans and the environments that they occupied. In the introduction to first thematic set,","PeriodicalId":54647,"journal":{"name":"Palaios","volume":"37 1","pages":"701 - 702"},"PeriodicalIF":1.6,"publicationDate":"2022-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43904343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT: The late Paleozoic transition is well represented by the upper Pennsylvanian to lower Permian Conemaugh, Monongahela, and Dunkard groups of the western Appalachian Basin (U.S.A.). These units contain abundant paleosols possessing suites of ichnofossils that serve as indicators of soil moisture, soil organic content, water table level, precipitation, and landscape stability. Analysis of these units can, therefore, be used to refine the details of how late Paleozoic terrestrial landscapes changed through time. A study along a 50 km west-east and a 40 km north-south transect through southeast Ohio and southwest West Virginia resulted in the recognition of 24 pedotypes with distinct ichnofossil assemblages. Ichnofossils include rhizoliths, Planolites, Palaeophycus, Taenidium, Scoyenia, Macanopsis, Skolithos, Cylindricum, cf. Psilonichnus, Arenicolites, mottles, and coprolites produced by various plants, gastropods, and larval-to-adult soil arthropods. Soil-forming environments include palustrine, levee, proximal to distal floodplain, interfluve, backswamp, marsh, and fen settings. An up-section shift in pedotypes from Argillisols to Vertisols and Calcisols as well as an overall increase in the diversity of pedotypes recorded a change in soil-forming conditions, resulting in a diverse landscape that changed significantly as mean annual precipitation rose and fell. An up-section increase in ichnofossil diversity in the paleosols and changes in ichnocoenoses suggests an increased dependence on the soil as a refuge and as a food resource. Overall, growing instability of the climate during the Pennsylvanian–Permian transition led to a more heterogeneous landscape that helped to promote colonization of a more diverse assemblage of soil organisms.
{"title":"EARLY EFFECTS OF THE LATE PALEOZOIC CLIMATE TRANSITION ON SOIL ECOSYSTEMS OF THE APPALACHIAN BASIN (CONEMAUGH, MONONGAHELA, AND DUNKARD GROUPS): EVIDENCE FROM ICHNOFOSSILS","authors":"Daniel I. Hembree","doi":"10.2110/palo.2021.071","DOIUrl":"https://doi.org/10.2110/palo.2021.071","url":null,"abstract":"ABSTRACT: The late Paleozoic transition is well represented by the upper Pennsylvanian to lower Permian Conemaugh, Monongahela, and Dunkard groups of the western Appalachian Basin (U.S.A.). These units contain abundant paleosols possessing suites of ichnofossils that serve as indicators of soil moisture, soil organic content, water table level, precipitation, and landscape stability. Analysis of these units can, therefore, be used to refine the details of how late Paleozoic terrestrial landscapes changed through time. A study along a 50 km west-east and a 40 km north-south transect through southeast Ohio and southwest West Virginia resulted in the recognition of 24 pedotypes with distinct ichnofossil assemblages. Ichnofossils include rhizoliths, Planolites, Palaeophycus, Taenidium, Scoyenia, Macanopsis, Skolithos, Cylindricum, cf. Psilonichnus, Arenicolites, mottles, and coprolites produced by various plants, gastropods, and larval-to-adult soil arthropods. Soil-forming environments include palustrine, levee, proximal to distal floodplain, interfluve, backswamp, marsh, and fen settings. An up-section shift in pedotypes from Argillisols to Vertisols and Calcisols as well as an overall increase in the diversity of pedotypes recorded a change in soil-forming conditions, resulting in a diverse landscape that changed significantly as mean annual precipitation rose and fell. An up-section increase in ichnofossil diversity in the paleosols and changes in ichnocoenoses suggests an increased dependence on the soil as a refuge and as a food resource. Overall, growing instability of the climate during the Pennsylvanian–Permian transition led to a more heterogeneous landscape that helped to promote colonization of a more diverse assemblage of soil organisms.","PeriodicalId":54647,"journal":{"name":"Palaios","volume":"37 1","pages":"671 - 690"},"PeriodicalIF":1.6,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44048253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
April A. Miller, J. Huntley, Evan P. Anderson, Sarah M. Jacquet
Abstract: Here we describe an epibiont association between conulariids and holdfast producers, with attachment scars resembling those of the tubular epibiont, Sphenothallus, from the Silurian (late Telychian Series) Brandon Bridge Formation, Wisconsin. The conulariid population represents the most abundant sessile organisms in the Waukesha Biota and consists of two species, Conularia niagarensis Hall, 1852 and Metaconularia cf. manni (Roy, 1935). Attachment scars present on the conulariid test offer a unique glimpse into the paleoecology of this Silurian benthic assemblage. However, body fossils of the attached epibiont are scarce and have not been observed attached or near conulariid specimens. This study evaluates the identity and paleoecological relationship between the conulariids and their enigmatic epibionts. Statistical analyses of attachment trace size, frequency, and distribution on the conulariid test gives insight to the nature of their symbiotic relationship. Our results did not find any significant support for a parasitic relationship. However, commensalism cannot be ruled out and serves as an alternative explanation for the relationship between these two organisms.
{"title":"BIOTIC INTERACTIONS BETWEEN CONULARIIDS AND EPIBIONTS FROM THE SILURIAN WAUKESHA BIOTA","authors":"April A. Miller, J. Huntley, Evan P. Anderson, Sarah M. Jacquet","doi":"10.2110/palo.2022.027","DOIUrl":"https://doi.org/10.2110/palo.2022.027","url":null,"abstract":"Abstract: Here we describe an epibiont association between conulariids and holdfast producers, with attachment scars resembling those of the tubular epibiont, Sphenothallus, from the Silurian (late Telychian Series) Brandon Bridge Formation, Wisconsin. The conulariid population represents the most abundant sessile organisms in the Waukesha Biota and consists of two species, Conularia niagarensis Hall, 1852 and Metaconularia cf. manni (Roy, 1935). Attachment scars present on the conulariid test offer a unique glimpse into the paleoecology of this Silurian benthic assemblage. However, body fossils of the attached epibiont are scarce and have not been observed attached or near conulariid specimens. This study evaluates the identity and paleoecological relationship between the conulariids and their enigmatic epibionts. Statistical analyses of attachment trace size, frequency, and distribution on the conulariid test gives insight to the nature of their symbiotic relationship. Our results did not find any significant support for a parasitic relationship. However, commensalism cannot be ruled out and serves as an alternative explanation for the relationship between these two organisms.","PeriodicalId":54647,"journal":{"name":"Palaios","volume":"37 1","pages":"691 - 699"},"PeriodicalIF":1.6,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43833934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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