A. Kemp, C. Vane, N. Khan, J. Ellison, S. Engelhart, B. Horton, D. Nikitina, Struan R. Smith, L. Rodrigues, R. Moyer
On low-lying, tropical and sub-tropical coastlines freshwater marshes may be replaced by salt‑tolerant mangroves in response to relative sea-level rise. Pollen analysis of radiocarbon‑dated sediment cores showed that such a change occurred in Hungry Bay, Bermuda during the late Holocene. This well-established paleoenvironmental trajectory provides an opportunity to explore if geochemical proxies (bulk-sediment δ13C and Rock-Eval pyrolysis) can reconstruct known environmental changes and relative sea level. We characterized surface sediment from depositional environments in Bermuda (freshwater wetlands, saline mangroves, and wrack composed of Sargassum natans macroalgae) using geochemical measurements and demonstrate that a multi-proxy approach can objectively distinguish among these environments. However, application of these techniques to the transgressive sediment succession beneath Hungry Bay suggests that freshwater peat and mangrove peat cannot be reliably distinguished in the sedimentary record, possibly because of post‑depositional convergence of geochemical characteristics on decadal to multi‑century timescales and/or the relatively small number of modern samples analyzed. Sediment that includes substantial contributions from Sargassum is readily identified by geochemistry, but has a limited spatial extent. Radiocarbon dating indicates that beginning at –700 CE, episodic marine incursions into Hungry Bay (e.g., during storms) carried Sargassum that accumulated as wrack and thickened through repeated depositional events until ~300 CE. It took a further ~550 years for a peat‑forming mangrove community to colonize Hungry Bay, which then accumulated sediment rapidly, but likely out of equilibrium with regional relative sea-level rise.
{"title":"Testing the Utility of Geochemical Proxies to Reconstruct Holocene Coastal Environments and Relative Sea Level: A Case Study from Hungry Bay, Bermuda","authors":"A. Kemp, C. Vane, N. Khan, J. Ellison, S. Engelhart, B. Horton, D. Nikitina, Struan R. Smith, L. Rodrigues, R. Moyer","doi":"10.5334/OQ.49","DOIUrl":"https://doi.org/10.5334/OQ.49","url":null,"abstract":"On low-lying, tropical and sub-tropical coastlines freshwater marshes may be replaced by salt‑tolerant mangroves in response to relative sea-level rise. Pollen analysis of radiocarbon‑dated sediment cores showed that such a change occurred in Hungry Bay, Bermuda during the late Holocene. This well-established paleoenvironmental trajectory provides an opportunity to explore if geochemical proxies (bulk-sediment δ13C and Rock-Eval pyrolysis) can reconstruct known environmental changes and relative sea level. We characterized surface sediment from depositional environments in Bermuda (freshwater wetlands, saline mangroves, and wrack composed of Sargassum natans macroalgae) using geochemical measurements and demonstrate that a multi-proxy approach can objectively distinguish among these environments. However, application of these techniques to the transgressive sediment succession beneath Hungry Bay suggests that freshwater peat and mangrove peat cannot be reliably distinguished in the sedimentary record, possibly because of post‑depositional convergence of geochemical characteristics on decadal to multi‑century timescales and/or the relatively small number of modern samples analyzed. Sediment that includes substantial contributions from Sargassum is readily identified by geochemistry, but has a limited spatial extent. Radiocarbon dating indicates that beginning at –700 CE, episodic marine incursions into Hungry Bay (e.g., during storms) carried Sargassum that accumulated as wrack and thickened through repeated depositional events until ~300 CE. It took a further ~550 years for a peat‑forming mangrove community to colonize Hungry Bay, which then accumulated sediment rapidly, but likely out of equilibrium with regional relative sea-level rise.","PeriodicalId":37172,"journal":{"name":"Open Quaternary","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47241452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Late Quaternary packrat (Neotoma spp.) midden plant macrofossil record in western North America is an exceptional record of biotic change that provides strong evidence of past climate. In this study, we generate quantitative estimates of climate from plant community composition of more than 600 individual paleomiddens over the past 50,000 years. Here we present the first large-scale application of CRACLE (Climate Reconstruction Analysis using Coexistence Likelihood Estimation), a quantitative climate inference method that uses plant community composition as a climate proxy under the individualistic concept of plant community assembly. The results are spatiotemporally specific estimates of temperature, precipitation, available moisture, and seasonal patterns that are consistent with well understood global climate patterns but provide previously unavailable detail and precision of the regional paleoclimate in western North America. Rapid warming is estimated at the Pleistocene-Holocene transition, at a conservative estimate of ca. 1°C per millennium. Previously projected future temperature increases suggest a rate of increase of more than 2°C over the next century, an astonishing 10× the rate experienced at any point during the past 50,000 years in Western North America. These analyses form a baseline demonstration of how the growing paleoecological record of packrat midden plant macrofossils can provide quantitative estimates of paleoclimate that aid in understanding the complexities of, and biotic responses to the regional climate system. This work is the first synthetic application of any paleoclimate estimation method to packrat midden plant macrofossils.
{"title":"Quantitative Late Quaternary Climate Reconstruction from Plant Macrofossil Communities in Western North America","authors":"R. Harbert, K. Nixon","doi":"10.5334/OQ.46","DOIUrl":"https://doi.org/10.5334/OQ.46","url":null,"abstract":"The Late Quaternary packrat (Neotoma spp.) midden plant macrofossil record in western North America is an exceptional record of biotic change that provides strong evidence of past climate. In this study, we generate quantitative estimates of climate from plant community composition of more than 600 individual paleomiddens over the past 50,000 years. Here we present the first large-scale application of CRACLE (Climate Reconstruction Analysis using Coexistence Likelihood Estimation), a quantitative climate inference method that uses plant community composition as a climate proxy under the individualistic concept of plant community assembly. The results are spatiotemporally specific estimates of temperature, precipitation, available moisture, and seasonal patterns that are consistent with well understood global climate patterns but provide previously unavailable detail and precision of the regional paleoclimate in western North America. Rapid warming is estimated at the Pleistocene-Holocene transition, at a conservative estimate of ca. 1°C per millennium. Previously projected future temperature increases suggest a rate of increase of more than 2°C over the next century, an astonishing 10× the rate experienced at any point during the past 50,000 years in Western North America. These analyses form a baseline demonstration of how the growing paleoecological record of packrat midden plant macrofossils can provide quantitative estimates of paleoclimate that aid in understanding the complexities of, and biotic responses to the regional climate system. This work is the first synthetic application of any paleoclimate estimation method to packrat midden plant macrofossils.","PeriodicalId":37172,"journal":{"name":"Open Quaternary","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47619922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tertiary dentine forms when an odontoblast is directly affected by stimuli, commonly through occlusal wear. In this study the presence of tertiary dentine is recorded in three South African fossil hominin species (Australopithecus africanus, Homo naledi and Paranthropus robustus), and two extant great ape species (Gorilla gorilla gorilla and Pan troglodytes). Frequencies of tertiary dentine were calculated for each species based on macroscopic observations of teeth with dentine exposed through occlusal wear. Overall, the three hominin species have similar tertiary dentine frequencies ranging from 12% to 16.13%. In contrast, over 90% of gorilla teeth with dentine visible show tertiary dentine. Chimpanzees fall between these extremes with 47.21% of teeth affected. Species variances are not related to differences in occlusal wear. Instead, some species appear predisposed to produce tertiary dentine earlier and/or faster than other species. Therefore, tertiary dentine formation has the potential to provide useful information on fossil specimens. For example, the uniformly low rate of tertiary dentine formation in hominins may be due to thick enamel having a similar role in preventing loss of function of teeth, i.e., extending the life of a tooth. In contrast tertiary dentine is clearly an important mechanism for normal dental function in gorillas, and may have evolved to maintain sheering surfaces for masticating tough vegetation.
{"title":"Tertiary Dentine Frequencies in Extant Great Apes and Fossil Hominins","authors":"I. Towle","doi":"10.5334/OQ.48","DOIUrl":"https://doi.org/10.5334/OQ.48","url":null,"abstract":"Tertiary dentine forms when an odontoblast is directly affected by stimuli, commonly through occlusal wear. In this study the presence of tertiary dentine is recorded in three South African fossil hominin species (Australopithecus africanus, Homo naledi and Paranthropus robustus), and two extant great ape species (Gorilla gorilla gorilla and Pan troglodytes). Frequencies of tertiary dentine were calculated for each species based on macroscopic observations of teeth with dentine exposed through occlusal wear. Overall, the three hominin species have similar tertiary dentine frequencies ranging from 12% to 16.13%. In contrast, over 90% of gorilla teeth with dentine visible show tertiary dentine. Chimpanzees fall between these extremes with 47.21% of teeth affected. Species variances are not related to differences in occlusal wear. Instead, some species appear predisposed to produce tertiary dentine earlier and/or faster than other species. Therefore, tertiary dentine formation has the potential to provide useful information on fossil specimens. For example, the uniformly low rate of tertiary dentine formation in hominins may be due to thick enamel having a similar role in preventing loss of function of teeth, i.e., extending the life of a tooth. In contrast tertiary dentine is clearly an important mechanism for normal dental function in gorillas, and may have evolved to maintain sheering surfaces for masticating tough vegetation.","PeriodicalId":37172,"journal":{"name":"Open Quaternary","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43616727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Welker, S. Billings, Jonathan A. Burns, S. McClure
Early British generals faced serious challenges in delivering and storing sufficient provisions for 18 th century British soldiers and colonial militia. This analysis investigates the influence of developed road systems that facilitated delivery of provisions and resulted in distinctive dietary patterning. The comparison of faunal data from forts located on major road systems with frontier garrisons and associated Native American villages like Fort Shirley and Aughwick Old Town, a short-lived (1754–1756) French and Indian War frontier fortification in central Pennsylvania, indicates a significantly reduced reliance on domestic livestock at these more inaccessible locations. These results suggest that road infrastructure heavily influenced military provisioning, encouraged adaptation to frontier living through reliance on wild game, and resulted in varied dietary practices at military installations in eastern North America.
{"title":"Roads and Military Provisioning During the French and Indian War\u0000 (1754–1763): The Faunal Remains of Fort Shirley, PA in Context","authors":"M. Welker, S. Billings, Jonathan A. Burns, S. McClure","doi":"10.5334/OQ.40","DOIUrl":"https://doi.org/10.5334/OQ.40","url":null,"abstract":"Early British generals faced serious challenges in delivering and storing sufficient provisions for 18 th century British soldiers and colonial militia. This analysis investigates the influence of developed road systems that facilitated delivery of provisions and resulted in distinctive dietary patterning. The comparison of faunal data from forts located on major road systems with frontier garrisons and associated Native American villages like Fort Shirley and Aughwick Old Town, a short-lived (1754–1756) French and Indian War frontier fortification in central Pennsylvania, indicates a significantly reduced reliance on domestic livestock at these more inaccessible locations. These results suggest that road infrastructure heavily influenced military provisioning, encouraged adaptation to frontier living through reliance on wild game, and resulted in varied dietary practices at military installations in eastern North America.","PeriodicalId":37172,"journal":{"name":"Open Quaternary","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45970426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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