1,721,103 research outputs found
Pheomelanin pigment remnants mapped in fossils of an extinct mammal
Get PDFRecent progress has been made in palaeontology with respect to resolving pigmentation in fossil material. Morphological identification of fossilized melanosomes has been one approach, while a second methodology using chemical imaging and spectroscopy has also provided critical information particularly concerning eumelanin (black pigment) residue. In this work we develop the chemical imaging methodology to show that organosulfur-Zn complexes are indicators of pheomelanin (red pigment) in extant and fossil soft tissue and that the mapping of these residual biochemical compounds can be used to restore melanin pigment distribution in a 3 million year old extinct mammal species (Apodemus atavus). Synchotron Rapid Scanning X-ray Fluorescence imaging showed that the distributions of Zn and organic S are correlated within this fossil fur just as in pheomelanin-rich modern integument. Furthermore, Zn coordination chemistry within this fossil fur is closely comparable to that determined from pheomelanin-rich fur and hair standards. The non-destructive methods presented here provide a protocol for detecting residual pheomelanin in precious specimens
Stable isotope data for Sturgeon and Paddlefish specimens, Leaf Mining Data, and Yearling Fish Sizes from the Tanis Location in the Hell Creek Formation of North Dakota (U.S.A.): Leaf Mining
No full textFossil specimens were obtained via field work over several years (2014-2021) at the Tanis site, in North Dakota, U.S.A. The specimens include: i) Sub-samples of sturgeon spines and paddlefish dentaries which were epoxy impregnated and sectioned using facilities at Florida Atlantic University. In 2024 a set of these samples were analyzed for stable isotope zonation (carbon and oxygen) at the Department of Earth Sciences, Durham University (UK). A customized micromill setup (computer-controlled ESI/New Wave Micromill with a 500 micron tungsten carbide drill bit) was used to sample fossil sturgeon and paddlefish specimens. Powders were removed by micro-spatula and weighed, with location of drill trace relative to outermost specimen edge logged via high resolution camera imaging. Powders were then analyzed by a Thermo-Finnigan (now Thermo Fisher Scientific) MAT 253 Isotope Ratio Mass Spectrometer into which CO2 was introduced through a Gasbench II device (external precision of about 0.05–0.10‰). Fossil fish powder samples were dissolved in 10 drops of orthophosphoric acid (H3PO4) under a helium (grade 5) atmosphere in exetainer vials. The solution was left to digest at 50 °C for two hours. The resultant gas mixture (CO2 and He) was introduced to a gas chromatographic column to isolate CO2. After passing a second water trap the CO2 was admitted to the mass spectrometer. Each sample run measured isotope ratios in 16 or 17 fossil fish powders and multiple replicates of four reference standards: 1) IAEA (International Atomic Energy Agency) international reference material CO1 (marble), 2) IAEA reference material LS VEC (lithium carbonate), 3) Durham internal standard DCS01 (calcite), and 4) a Durham internal standard DOBINS (equine hydroxyapatite). 13C/12C and 18O/16O ratios are reported as d values (‰ deviations) relative to Vienna PeeDee Belemnite (VPDB). ii) Fossil angiosperm leaves from the time-synchronous Chicxulub Event Deposit, sedimentary units 2a-c, were analyzed for the presence of insect leaf-mining traces, and a tally of trace absent vs. trace present specimens recorded. iii) Fossils of sub-yearling (young-of-year) fish from Unit 2a were also examined. Here. these were identified as members of one of three groups: sturgeon, paddlefish, or Amiidae, and their lengths and orientations recorded. iv) Synchrotron Rapid Scanning-X-ray Fluorescence (SRS-XRF) imaging was performed in this study at wiggler beamline 6-2 (SSRL). Incident beam energy for the experiments was set at 3.15 keV (flux ~10^9 photons-1) for Low-Z mapping and specimens were analysed within a He-purged chamber. Experiments utilized a beam diameter of either 50 or 100 µm, defined by a pinhole. A four-element Vortex ME4 silicon drift detector was used to detect fluoresced X-rays
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Stable isotope data for Sturgeon and Paddlefish specimens, Leaf Mining Data, and Yearling Fish Sizes from the Tanis Location in the Hell Creek Formation of North Dakota (U.S.A.): Synchrotron Data
No full textFossil specimens were obtained via field work over several years (2014-2021) at the Tanis site, in North Dakota, U.S.A. The specimens include: i) Sub-samples of sturgeon spines and paddlefish dentaries which were epoxy impregnated and sectioned using facilities at Florida Atlantic University. In 2024 a set of these samples were analyzed for stable isotope zonation (carbon and oxygen) at the Department of Earth Sciences, Durham University (UK). A customized micromill setup (computer-controlled ESI/New Wave Micromill with a 500 micron tungsten carbide drill bit) was used to sample fossil sturgeon and paddlefish specimens. Powders were removed by micro-spatula and weighed, with location of drill trace relative to outermost specimen edge logged via high resolution camera imaging. Powders were then analyzed by a Thermo-Finnigan (now Thermo Fisher Scientific) MAT 253 Isotope Ratio Mass Spectrometer into which CO2 was introduced through a Gasbench II device (external precision of about 0.05–0.10‰). Fossil fish powder samples were dissolved in 10 drops of orthophosphoric acid (H3PO4) under a helium (grade 5) atmosphere in exetainer vials. The solution was left to digest at 50 °C for two hours. The resultant gas mixture (CO2 and He) was introduced to a gas chromatographic column to isolate CO2. After passing a second water trap the CO2 was admitted to the mass spectrometer. Each sample run measured isotope ratios in 16 or 17 fossil fish powders and multiple replicates of four reference standards: 1) IAEA (International Atomic Energy Agency) international reference material CO1 (marble), 2) IAEA reference material LS VEC (lithium carbonate), 3) Durham internal standard DCS01 (calcite), and 4) a Durham internal standard DOBINS (equine hydroxyapatite). 13C/12C and 18O/16O ratios are reported as d values (‰ deviations) relative to Vienna PeeDee Belemnite (VPDB). ii) Fossil angiosperm leaves from the time-synchronous Chicxulub Event Deposit, sedimentary units 2a-c, were analyzed for the presence of insect leaf-mining traces, and a tally of trace absent vs. trace present specimens recorded. iii) Fossils of sub-yearling (young-of-year) fish from Unit 2a were also examined. Here. these were identified as members of one of three groups: sturgeon, paddlefish, or Amiidae, and their lengths and orientations recorded. iv) Synchrotron Rapid Scanning-X-ray Fluorescence (SRS-XRF) imaging was performed in this study at wiggler beamline 6-2 (SSRL). Incident beam energy for the experiments was set at 3.15 keV (flux ~10^9 photons-1) for Low-Z mapping and specimens were analysed within a He-purged chamber. Experiments utilized a beam diameter of either 50 or 100 µm, defined by a pinhole. A four-element Vortex ME4 silicon drift detector was used to detect fluoresced X-rays
Stable isotope data for Sturgeon and Paddlefish specimens, Leaf Mining Data, and Yearling Fish Sizes from the Tanis Location in the Hell Creek Formation of North Dakota (U.S.A.): Fish Sizes
No full textFossil specimens were obtained via field work over several years (2014-2021) at the Tanis site, in North Dakota, U.S.A. The specimens include: i) Sub-samples of sturgeon spines and paddlefish dentaries which were epoxy impregnated and sectioned using facilities at Florida Atlantic University. In 2024 a set of these samples were analyzed for stable isotope zonation (carbon and oxygen) at the Department of Earth Sciences, Durham University (UK). A customized micromill setup (computer-controlled ESI/New Wave Micromill with a 500 micron tungsten carbide drill bit) was used to sample fossil sturgeon and paddlefish specimens. Powders were removed by micro-spatula and weighed, with location of drill trace relative to outermost specimen edge logged via high resolution camera imaging. Powders were then analyzed by a Thermo-Finnigan (now Thermo Fisher Scientific) MAT 253 Isotope Ratio Mass Spectrometer into which CO2 was introduced through a Gasbench II device (external precision of about 0.05–0.10‰). Fossil fish powder samples were dissolved in 10 drops of orthophosphoric acid (H3PO4) under a helium (grade 5) atmosphere in exetainer vials. The solution was left to digest at 50 °C for two hours. The resultant gas mixture (CO2 and He) was introduced to a gas chromatographic column to isolate CO2. After passing a second water trap the CO2 was admitted to the mass spectrometer. Each sample run measured isotope ratios in 16 or 17 fossil fish powders and multiple replicates of four reference standards: 1) IAEA (International Atomic Energy Agency) international reference material CO1 (marble), 2) IAEA reference material LS VEC (lithium carbonate), 3) Durham internal standard DCS01 (calcite), and 4) a Durham internal standard DOBINS (equine hydroxyapatite). 13C/12C and 18O/16O ratios are reported as d values (‰ deviations) relative to Vienna PeeDee Belemnite (VPDB). ii) Fossil angiosperm leaves from the time-synchronous Chicxulub Event Deposit, sedimentary units 2a-c, were analyzed for the presence of insect leaf-mining traces, and a tally of trace absent vs. trace present specimens recorded. iii) Fossils of sub-yearling (young-of-year) fish from Unit 2a were also examined. Here. these were identified as members of one of three groups: sturgeon, paddlefish, or Amiidae, and their lengths and orientations recorded. iv) Synchrotron Rapid Scanning-X-ray Fluorescence (SRS-XRF) imaging was performed in this study at wiggler beamline 6-2 (SSRL). Incident beam energy for the experiments was set at 3.15 keV (flux ~10^9 photons-1) for Low-Z mapping and specimens were analysed within a He-purged chamber. Experiments utilized a beam diameter of either 50 or 100 µm, defined by a pinhole. A four-element Vortex ME4 silicon drift detector was used to detect fluoresced X-rays
Stable isotope data for Sturgeon and Paddlefish specimens, Leaf Mining Data, and Yearling Fish Sizes from the Tanis Location in the Hell Creek Formation of North Dakota (U.S.A.)
No full textFossil specimens were obtained via field work over several years (2014-2021) at the Tanis site, in North Dakota, U.S.A. The specimens include: i) Sub-samples of sturgeon spines and paddlefish dentaries which were epoxy impregnated and sectioned using facilities at Florida Atlantic University. In 2024 a set of these samples were analyzed for stable isotope zonation (carbon and oxygen) at the Department of Earth Sciences, Durham University (UK). A customized micromill setup (computer-controlled ESI/New Wave Micromill with a 500 micron tungsten carbide drill bit) was used to sample fossil sturgeon and paddlefish specimens. Powders were removed by micro-spatula and weighed, with location of drill trace relative to outermost specimen edge logged via high resolution camera imaging. Powders were then analyzed by a Thermo-Finnigan (now Thermo Fisher Scientific) MAT 253 Isotope Ratio Mass Spectrometer into which CO2 was introduced through a Gasbench II device (external precision of about 0.05–0.10‰). Fossil fish powder samples were dissolved in 10 drops of orthophosphoric acid (H3PO4) under a helium (grade 5) atmosphere in exetainer vials. The solution was left to digest at 50 °C for two hours. The resultant gas mixture (CO2 and He) was introduced to a gas chromatographic column to isolate CO2. After passing a second water trap the CO2 was admitted to the mass spectrometer. Each sample run measured isotope ratios in 16 or 17 fossil fish powders and multiple replicates of four reference standards: 1) IAEA (International Atomic Energy Agency) international reference material CO1 (marble), 2) IAEA reference material LS VEC (lithium carbonate), 3) Durham internal standard DCS01 (calcite), and 4) a Durham internal standard DOBINS (equine hydroxyapatite). 13C/12C and 18O/16O ratios are reported as d values (‰ deviations) relative to Vienna PeeDee Belemnite (VPDB). ii) Fossil angiosperm leaves from the time-synchronous Chicxulub Event Deposit, sedimentary units 2a-c, were analyzed for the presence of insect leaf-mining traces, and a tally of trace absent vs. trace present specimens recorded. iii) Fossils of sub-yearling (young-of-year) fish from Unit 2a were also examined. Here. these were identified as members of one of three groups: sturgeon, paddlefish, or Amiidae, and their lengths and orientations recorded. iv) Synchrotron Rapid Scanning-X-ray Fluorescence (SRS-XRF) imaging was performed in this study at wiggler beamline 6-2 (SSRL). Incident beam energy for the experiments was set at 3.15 keV (flux ~10^9 photons-1) for Low-Z mapping and specimens were analysed within a He-purged chamber. Experiments utilized a beam diameter of either 50 or 100 µm, defined by a pinhole. A four-element Vortex ME4 silicon drift detector was used to detect fluoresced X-rays
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