| 1. |
- Betts, Marissa, J., et al.
(författare)
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Early Cambrian chronostratigraphy and geochronology of South Australia
- 2018
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Ingår i: Earth-Science Reviews. - : Elsevier BV. - 0012-8252 .- 1872-6828. ; 185, s. 498-543
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Tidskriftsartikel (refereegranskat)abstract
- The most successful chronostratigraphic correlation methods enlist multiple proxies such as biostratigraphy and chemostratigraphy to constrain the timing of globally important bio- and geo-events. Here we present the first regional, high-resolution shelly fossil biostratigraphy integrated with δ13C chemostratigraphy (and corresponding δ18O data) from the traditional lower Cambrian (Terreneuvian and provisional Cambrian Series 2) of South Australia. The global ZHUCE, SHICE, positive excursions II and III and the CARE are captured in lower Cambrian successions from the Arrowie and Stansbury basins. The South Australian shelly fossil biostratigraphy has a consistent relationship with the δ13C results, bolstering interpretation, identification and correlation of the excursions. Positive excursion II straddles the boundary between the Kulparina rostrata and Micrina etheridgei zones, and the CARE straddles the boundary between the M. etheridgei and Dailyatia odyssei zones, peaking in the lower parts of the latter zone. New CA-TIMS zircon dates from the upper Hawker Group and Billy Creek Formation provide geochronologic calibration points for the upper D. odyssei Zone and corresponding chemostratigraphic curve, embedding the lower Cambrian successions from South Australia into a global chronostratigraphic context. This multi-proxy investigation demonstrates the power of integrated methods for developing regional biostratigraphic schemes and facilitating robust global correlation of lower Cambrian successions from South Australia (part of East Gondwana) with coeval terranes on other Cambrian palaeocontinents, including South and North China, Siberia, Laurentia, Avalonia and West Gondwana.
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| 2. |
- Agbaje, Oluwatoosin B. A., et al.
(författare)
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Biomacromolecules in recent phosphate-shelled brachiopods : identification and characterization of chitin matrix
- 2021
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Ingår i: Journal of Materials Science. - : Springer Nature. - 0022-2461 .- 1573-4803. ; 56:36, s. 19884-19898
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Tidskriftsartikel (refereegranskat)abstract
- Phosphate-shelled brachiopods differ in filter-feeding lifestyle, with Lingula anatina an active infaunal burrower, and Discinisca tenuis a shallow marine epibenthic animal. The shells of these animals are built of organophosphatic constituents, the organic fibres/sheets reinforced with calcium phosphate to provide a sophisticated ultrastructural robustness. This investigation examined the nature of the organic fibres in order to improve understanding of how living organisms produce hierarchically structured biomaterials. Unlike powdered samples commonly used in previous studies, organic fibres were isolated for the first time and the shell fractions were purified, in order to study the content and nature of the biopolymer fibres. Biochemical methods including Calcofluor staining revealed a chitin matrix. Ultrastructural analysis, thermal gravimetric analysis, and spectroscopic analyses show that the core polysaccharide framework is composed of layers of β-chitin sheets and/or fibrils that are coated with a fibrous organic matrix. There is more chitin matrix in the L. anatina shells (26.6 wt.%) compared to the D. tenuis shells (12.9 wt.%). Taken together, the data show that the chitin matrix contributes to increased skeletal strength, making L. anatina highly adapted for life as an active burrower. In comparison, D. tenuis contains less chitin and lives as attached epibenthos in a shallow marine environment.
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| 3. |
- Agbaje, Oluwatoosin B. A., et al.
(författare)
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Characterization of organophosphatic brachiopod shells : spectroscopic assessment of collagen matrix and biomineral components
- 2020
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Ingår i: RSC Advances. - 2046-2069. ; 10, s. 38456-38467
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Tidskriftsartikel (refereegranskat)abstract
- The shells of linguloid brachiopods such as Lingula and Discinisca are inorganic–organic nanocomposites with a mineral phase of calcium phosphate (Ca-phosphate). Collagen, the main extracellular matrix in Ca-phosphatic vertebrate skeletons, has not previously been clearly resolved at the molecular level in organophosphatic brachiopods. Here, modern and recently-alive linguliform brachiopod shells of Lingula and Discinisca have been studied by microRaman spectroscopy, Fourier transform infrared spectroscopy, field emission gun scanning electron microscopy, and thermal gravimetric analysis. For the first time, biomineralized collagen matrix and Ca-phosphate components were simultaneously identified, showing that the collagen matrix is an important moiety in organophosphatic brachiopod shells, in addition to prevalent chitin. Stabilized nanosized apatitic biominerals (up to ∼50 nm) permeate the framework of organic fibrils. There is a ∼2.5-fold higher wt% of carbonate (CO32−) in Lingula versus Discinisca shells. Both microRaman spectroscopy and infrared spectra show transient amorphous Ca-phosphate and octacalcium phosphate components. For the first time, trivalent moieties at ∼1660 cm−1 and divalent moieties at ∼1690 cm−1 in the amide I spectral region were identified. These are related to collagen cross-links that are abundant in mineralized tissues, and could be important features in the biostructural and mechanical properties of Ca-phosphate shell biominerals. This work provides a critical new understanding of organophosphatic brachiopod shells, which are some of the earliest examples of biomineralization in still-living animals that appeared in the Cambrian radiation.
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| 4. |
- Teece, Bronwyn L., et al.
(författare)
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Mars Rover Techniques and Lower/Middle Cambrian Microbialites from South Australia : Construction, Biofacies, and Biogeochemistry
- 2020
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Ingår i: Astrobiology. - : MARY ANN LIEBERT, INC. - 1531-1074 .- 1557-8070. ; 20:5, s. 637-657
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Tidskriftsartikel (refereegranskat)abstract
- The Perseverance rover (Mars 2020) is equipped with an instrumental and analytical payload capable of identifying a broad range of organic molecules in geological samples. To determine the efficacy of these analytical techniques in recognizing important ecological and environmental signals in the rock record, this study utilized analogous equipment, including gas chromatography/mass spectrometry, Raman spectroscopy, X-ray fluorescence (XRF), Fourier transform infrared spectroscopy, along with macroscopic and petrographic observations, to examine early-middle Cambrian microbialites from the Arrowie Basin, South Australia. Morphological and petrographic observations of these carbonate successions reveal evidence of hypersaline-restricted environments. Microbialites have undergone moderate diagenesis, as supported by XRF data that show mineral assemblages, including celestine and the illitization of smectite. Raman spectral data, carbon preference indices of similar to 1, and the methylphenanthrene index place the samples in the prehnite/pumpellyite metamorphic facies. Pristane and phytane are the only biomarkers that were detected in the least thermally mature samples. This research demonstrates a multitechnique approach that can yield significant geological, depositional, paleobiological, and diagenetic information that has important implications for planning future astrobiological exploration.
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| 5. |
- Topper, Timothy P, et al.
(författare)
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The oldest brachiopods from the lower Cambrian of South Australia
- 2013
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Ingår i: Acta Palaeontologica Polonica. - : Polska Akademia Nauk Instytut Paleobiologii (Institute of Paleobiology, Polish Academy of Sciences). - 0567-7920 .- 1732-2421. ; 58:1, s. 93-109
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Tidskriftsartikel (refereegranskat)abstract
- The morphology and organophosphatic shell structure of the paterinate brachiopod Askepasma is documented using new and previously collected specimens from the lower Cambrian of South Australia. Lack of adequately preserved material has seen the majority of paterinate specimens previously reported from South Australia referred to the genus Askepasma and treated under open nomenclature. Large collections of paterinates from the lower Cambrian Wilkawillina, Ajax, and Wirrapowie limestones in the Arrowie Basin, South Australia have prompted redescription of the type species Askepasma toddense and the erection of a new species, Askepasma saproconcha sp. nov. Askepasma saproconcha sp. nov. currently represents the oldest known brachiopod from the lower Cambrian successions in South Australia with a FAD in pre−trilobitic (Terreneuvian, Cambrian Stage 2, lower Atdabanian) strata in the basal part of the Wilkawillina and Wirrapowie limestones. Askepasma toddense predominantly occurs in Abadiella huoi Zone equivalent strata (Unnamed Cambrian Series 2, Stage 3, middle–upper Atdabanian) in the upper part of the lower Wilkawillina, Wirrapowie, and Ajax limestones. The shell microstructure of Askepasma suggests a proximal stem group position within the Brachiopoda and similarities with tommotiid taxa provides further evidence that the ancestry of crown group brachiopods is firmly entrenched within the Tommotiida.
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| 6. |
- Betts, Marissa J., et al.
(författare)
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A new early Cambrian bradoriid (Arthropoda) assemblage from the northern Flinders Ranges, South Australia
- 2014
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Ingår i: Gondwana Research. - : Elsevier BV. - 1342-937X .- 1878-0571. ; 25, s. 420-437
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Tidskriftsartikel (refereegranskat)abstract
- A new assemblage of early Cambrian bivalved arthropods (Bradoriida) is described from the Arrowie Syncline in the northern Flinders Ranges, South Australia. The well preserved, largely endemic fauna comprises a total of six taxa (including five new species): Jiucunella phaseloa sp. nov., Jixinlingella daimonikoa sp. nov., Mongolitubulus anthelios sp. nov., Neokunmingella moroensis sp. nov., Phasoia cf. spicata ( Öpik, 1968), and Sinskolutella cuspidata sp. nov. This assemblage is derived from a carbonate sedimentary package representing a high energy, shallow water archaeocyath-Renalcis biohermal facies of Terreneuvian, Stage 2 age which transitions up-section to a more restricted, low energy, intra-shelf lagoonal environment that correlates with a Cambrian Series 2, Stage 3 age. The new taxon J. phaseloa sp. nov., has a first appearance datum (FAD) in shallow water biohermal facies of the Hideaway Well Member of the Wilkawillina Limestone at a level 47 m below the FAD of Pelagiella subangulata which is taken to approximate the base of Series 2, Stage 3 in South Australia. Along with Liangshanella circumbolina, this makes J. phaseloa sp. nov. amongst the oldest bivalved arthropods in South Australia and potentially greater Gondwana. The presence of 25 bradoriid taxa from the early Cambrian of South Australia suggests East Gondwana represents a major centre of origin for the Bradoriida.
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| 7. |
- Betts, Marissa, J., et al.
(författare)
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A new lower Cambrian shelly fossil biostratigraphy for South Australia
- 2016
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Ingår i: Gondwana Research. - : Elsevier BV. - 1342-937X .- 1878-0571. ; 36, s. 163-195
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Tidskriftsartikel (refereegranskat)abstract
- Definition of early Cambrian chronostratigraphic boundaries is problematic with many subdivisions stillawaiting ratification. Integrated multi-proxy data from well-resolved regional-scale schemes are ultimately the key to resolving broader issues of global correlationwithin the Cambrian. In Australia, early Cambrian biostratigraphy has been based predominantly on trilobites. Phosphatic shelly fauna have great potential as biostratigraphic tools, especially in pre-trilobitic strata because they are widespread and readily preserved, but they have remained underutilised. Here we demonstrate their value in a new biostratigraphic scheme for the early Cambrian of South Australia using a diverse shelly fauna including tommotiids, brachiopods, molluscs and bradoriids. Biostratigraphic data are derived from ten measured stratigraphic sections across the Arrowie Basin, targeting Hawker Group carbonates including the Wilkawillina, Wirrapowie and Ajax limestones and the Mernmerna Formation. The stratigraphic ranges of shelly fossils are predictable and repeatable across the Arrowie Basin, allowing three discrete shelly biozones to be identified, spanning Terreneuvian, Stage 2 to Series 2, Stages 3–4. The Kulparina rostrata Zone (new) and part of the overlyingMicrina etheridgei Zone (new) are pre-trilobitic (predominantly Terreneuvian). The Cambrian Series 2, Stage 3 Dailyatia odyssei Zone (new) features a very diverse shelly fauna and will be described in detail in a separate publication. These zones provide robust means to correlate Terreneuvian–Series 2 successions in neighbouring coeval basins in Australia, particularly the Stansbury Basin. Wider correlation is possible throughout East Gondwana, and especially with South China.
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| 8. |
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| 9. |
- Betts, Marissa, J., et al.
(författare)
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Global correlation of the early Cambrian of South Australia: Shelly faunaof the Dailyatia odyssei Zone
- 2017
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Ingår i: Gondwana Research. - Amsterdam : Elsevier BV. - 1342-937X .- 1878-0571. ; 46, s. 240-279
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Tidskriftsartikel (refereegranskat)abstract
- A lack of well resolved biostratigraphic data has prevented robust regional and global correlation of lower Cambriansuccessions from South Australia. A new early Cambrian biostratigraphy, based on data derived from 21measured stratigraphic sections and drill cores (11 described herein) reveals the abundance and diversity ofshelly fauna from the Arrowie Basin, and the value of early Cambrian “small shelly fossils” (SSF) for biostratigraphicstudies. Here we examine shelly fauna associated with the youngest of three recently establishedbiozones, the Dailyatia odyssei Taxon Range Zone (hereafter D. odyssei Zone), and their correlative potential.The D. odyssei Zone features a diverse suite of tommotiids, organophosphatic brachiopods, bradoriid arthropods,molluscs and phosphatic problematica. This fauna permits strong correlation (often at species-level) with othermajor early Cambrian terranes, particularly Antarctica, South China and Laurentia, and suggest a Cambrian Series2, Stages 3–4 age for the D. odyssei Zone. Bradoriids have proven to be useful biostratigraphic tools. Four newspeciesand three new genera are described herein: Acutobalteus sinuosus gen. et sp. nov., Eozhexiella adnyamathanha gen. etsp. nov., Manawarra jonesi gen. et sp. nov. and Mongolitubulus descensus sp. nov. The description of Eohadrotreta sp.cf. zhenbaensis represents the first occurrence of the acrotretoid brachiopod Eohadrotreta from Australia.
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| 10. |
- Betts, Marissa J, et al.
(författare)
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Integrated chronostratigraphy of the lower Cambrian Byrd Group, Transantarctic Mountains
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Antarctica and Australia were sutured together straddling the equator during the major pulse of animal biodiversification associated with the Cambrian radiation. However, lack of detailed systematic sampling of lower Cambrian sedimentary packages from Antarctica has significantly impeded precise age determination and correlation with other Cambrian paleocontinents, especially with other parts of East Gondwana. Here were present new, integrated biostratigraphic and chemostratigraphic (δ13C isotopes) data from three stratigraphic sections measured through autochthonous shallow water carbonates (including archaeocyath-microbial bioherms) from the lower Cambrian Byrd Group in the Transantarctic Mountains. Recovered shelly fossil assemblages (brachiopods, tommotiids, molluscs, trilobites) from the Holyoake and Churchill Ranges include conspecific taxa previously described from Hawker Group rocks in the Arrowie Basin of South Australia facilitating direct correlation with the upper Dailyatia odyssei biozone. Synchronous chemostratigraphic data capture a distinctive positive ?13C excursion in the Churchill Range interpreted as the global Mingxinsi Carbon Isotope Excursion (MICE) peak. A succeeding gradual negative ?13C excursion captured in the Churchill and Holyoake sections is interpreted as the global Archaeocyathid Extinction Carbon Isotope Excursion (AECE) event. There is no chemostratigraphic evidence for the large Redlichiid-Olenellid Extinction Carbon Isotope Excursion (ROECE) negative event that straddles and defines the Cambrian Stage 4 – Miaolingian boundary. Hence, the integrated faunal and new chemostratigraphic data presented herein strongly support a Cambrian Stage 4 age for the upper Shackleton Limestone – Holyoake Formation – Starshot Formation succession of the Byrd Group.
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