ABSTRACT Based upon fragmentary remains of dermal armor, a new form of arandaspid fish, Ritchieic... more ABSTRACT Based upon fragmentary remains of dermal armor, a new form of arandaspid fish, Ritchieichthys nibili, gen et. sp. nov., is described from subsurface core material from the Katian (Late Ordovician) Nibil Formation of the Canning Basin, Western Australia. Ritchieichthys nibili represents the first documented record of a fish from the Ordovician of the Canning Basin. Allied to the previous descriptions of arandaspsids from the Amadeus and Warburton basins of the Northern Territory and New South Wales, respectively, this record extends the paleogeographic range of arandaspids across the hypothetical Ordovician Larapintine Seaway and increases the stratigraphic range of the Order Arandaspidiformes into the Katian. The hard tissue histology of Ritchieichthys nibili confirms the presence of a cellular dentine forming the bulk of the dermal armor ornament in arandaspids, a tissue that had not been directly observed previously, and confirms the presence of largely unconnected osteocytes within the dermal bone that forms the majority of the armor.
ABSTRACT Based upon fragmentary remains of dermal armor, a new form of arandaspid fish, Ritchieic... more ABSTRACT Based upon fragmentary remains of dermal armor, a new form of arandaspid fish, Ritchieichthys nibili, gen et. sp. nov., is described from subsurface core material from the Katian (Late Ordovician) Nibil Formation of the Canning Basin, Western Australia. Ritchieichthys nibili represents the first documented record of a fish from the Ordovician of the Canning Basin. Allied to the previous descriptions of arandaspsids from the Amadeus and Warburton basins of the Northern Territory and New South Wales, respectively, this record extends the paleogeographic range of arandaspids across the hypothetical Ordovician Larapintine Seaway and increases the stratigraphic range of the Order Arandaspidiformes into the Katian. The hard tissue histology of Ritchieichthys nibili confirms the presence of a cellular dentine forming the bulk of the dermal armor ornament in arandaspids, a tissue that had not been directly observed previously, and confirms the presence of largely unconnected osteocytes within the dermal bone that forms the majority of the armor.
Measured lithostratigraphic sections of the classic Permian–Triassic non-marine transitional sequ... more Measured lithostratigraphic sections of the classic Permian–Triassic non-marine transitional sequences covering the upper Quanzijie, Wutonggou, Guodikeng and lower Jiucaiyuan Formations at Dalongkou and Lucaogou, Xinjiang Province, China are presented. These measured sections form the framework and reference sections for a range of multi-disciplinary studies of the P–T transition in this large ancient lake basin, including palynostratigraphy, vertebrate biostratigraphy, chemostratigraphy and magnetostratigraphy. The 121 m thick Wutonggou Formation at Dalongkou includes 12 sandstone units ranging in thickness from 0.5 to 10.5 m that represent cyclical coarse terrigenous input to the lake basin during the Late Permian. The rhythmically-bedded, mudstone-dominated Guodikeng Formation is 197 m and 209 m thick on the north and south limbs of the Dalongkou anticline, respectively, and 129 m thick at Lucaogou. Based on limited palynological data, the Permian–Triassic boundary was previously placed approximately 50 m below the top of this formation at Dalongkou. This boundary does not coincide with any mappable lithologic unit, such as the basal sandstones of the overlying Jiucaiyuan Formation, assigned to the Early Triassic. The presence of multiple organic d13C-isotope excursions, mutant pollen, and multiple algal and conchostracan blooms in this formation, together with Late Permian palynomorphs, suggests that the Guodikeng Formation records multiple climatic perturbation signals representing environmental stress during the late Permian mass extinction interval. The overlap between the vertebrates Dicynodon and Lystrosaurus in the upper part of this formation, and the occurrence of late Permian spores and the latest Permian to earliest Triassic megaspore Otynisporites eotriassicus is consistent with a latest Permian age for at least part of the Guodikeng Formation. Palynostratigrahic placement of the Permian–Triassic boundary in the Junggar Basin remains problematic because key miospore taxa, such as Aratrisporites spp. are not present. Palynomorphs from the Guodikeng are assigned to two assemblages; the youngest, from the upper 100 m of the formation (and the overlying Jiucaiyuan Formation), contains both typical Permian elements and distinctive taxa that elsewhere are known from the Early Triassic of Canada, Greenland, Norway, and Russia. The latter include spores assigned to Pechorosporites disertus, Lundbladispora foveota, Naumovaspora striata, Decussatisporites mulstrigatus and Leptolepidites jonkerii. While the presence of Devonian and Carboniferous spores and Early Permian pollen demonstrate reworking is occurring in the Guodikeng assemblages, the sometimes common occurrence of Scutasporites sp. cf. Scutasporites unicus, and other pollen, suggests that the Late Permian elements are in place, and that the upper assemblage derives from a genuine transitional flora of Early Triassic aspect. In the Junggar Basin, biostratigraphic data and magnetostratigraphic data indicate that the Permian–Triassic boundary (GSSP Level) is in the middle to upper Guodikeng Formation and perhaps as high as the formational contact with the overlying Jiucaiyuan Formation.
The Early Triassic Induan–Olenekian Stage boundary (Dienerian–Smithian sub-stage boundary) has be... more The Early Triassic Induan–Olenekian Stage boundary (Dienerian–Smithian sub-stage boundary) has been identified at a depth of 2719.25 m in the petroleum exploration well Senecio-1 located in the northern Perth Basin,Western Australia. Conodont faunas represent three conodont zones in ascending order, the Neospathodus dieneri Zone, the Neospathodus waageni eowaageni Zone and the Neospathodus waageni waageni Zone. The Induan–Olenekian (Dienerian–Smithian) boundary is placed at the base of the Neospathodus waageni eowaageni Zone equivalent to the first appearance of Neospathodus ex. gr. waageni utilised elsewhere and adopted by the IUGS ICS Triassic Subcommission to define the base of the Olenekian. Bulk kerogen δ13C carbon isotopes define a positive peak of c. 4 per mille that essentially coincides with the Induan–Olenekian boundary as seen in proposed Global Stratotype Sections and Points (GSSPs) in South China and Spiti, India demonstrating the global utility of this level for correlation. An anoxic zone is recognised in the lower part of the Senecio-1 core and the upper limit of this zone is dated as late Induan (late Dienerian). Temporal and spatialmapping of marine anoxia and dysoxia globally demonstrates that pulses of dysoxia/anoxia affected shallow-marine zones at different times in different locations. Dysoxia/anoxia in the shallow-marine environment appeared in the latest Permian at the extinction level, later than in the deep-marine environment, and appears to be largely restricted to the Induan (Griesbachian and Dienerian) and early Olenekian (Smithian). Temporally and geographically restricted upwelling of an oxygenminimum zone into the ocean surface layer due to environmental perturbations including extreme global warming, increased terrestrial chemical weathering intensity and continental erosion, sea level rise, and changes in marine nutrient inventories and productivity rates, is interpreted as a likely cause of observed variation in shallow-marine dysoxia/anoxia in the Early Triassic.
The marine conodont fossil species, Hindeodus changxingensis Wang, that has a distinctive morphol... more The marine conodont fossil species, Hindeodus changxingensis Wang, that has a distinctive morphology, is restricted to a very narrow stratigraphic interval essentially from the Permian–Triassic extinction event through the internationally recognized boundary and into the very earliest Triassic. The species is geographically widespread in the Tethyan Region, from Italy to South China, and serves as a characteristic index fossil to reliably identify this short but critical interval that encompasses the greatest mass extinction of life on earth and the boundary between the Paleozoic and Mesozoic Eras.
ABSTRACT Based upon fragmentary remains of dermal armor, a new form of arandaspid fish, Ritchieic... more ABSTRACT Based upon fragmentary remains of dermal armor, a new form of arandaspid fish, Ritchieichthys nibili, gen et. sp. nov., is described from subsurface core material from the Katian (Late Ordovician) Nibil Formation of the Canning Basin, Western Australia. Ritchieichthys nibili represents the first documented record of a fish from the Ordovician of the Canning Basin. Allied to the previous descriptions of arandaspsids from the Amadeus and Warburton basins of the Northern Territory and New South Wales, respectively, this record extends the paleogeographic range of arandaspids across the hypothetical Ordovician Larapintine Seaway and increases the stratigraphic range of the Order Arandaspidiformes into the Katian. The hard tissue histology of Ritchieichthys nibili confirms the presence of a cellular dentine forming the bulk of the dermal armor ornament in arandaspids, a tissue that had not been directly observed previously, and confirms the presence of largely unconnected osteocytes within the dermal bone that forms the majority of the armor.
Abstract Until recently it has been widely accepted that protoliths to metasediments of the Harts... more Abstract Until recently it has been widely accepted that protoliths to metasediments of the Harts Range Metamorphic Complex (central Australia) were deposited prior to c. 1.75 Ga and form part of the Palaeoproterozoic Arunta Inlier. However, new sensitive high-resolution ion microprobe U–Pb analyses of detrital zircon, together with recently published data, suggest that they were deposited coeval with c. 545–520 Ma sediments from the adjacent, little metamorphosed Neoproterozoic to Palaeozoic Centralian Superbasin. Protoliths of ...
ABSTRACT Based upon fragmentary remains of dermal armor, a new form of arandaspid fish, Ritchieic... more ABSTRACT Based upon fragmentary remains of dermal armor, a new form of arandaspid fish, Ritchieichthys nibili, gen et. sp. nov., is described from subsurface core material from the Katian (Late Ordovician) Nibil Formation of the Canning Basin, Western Australia. Ritchieichthys nibili represents the first documented record of a fish from the Ordovician of the Canning Basin. Allied to the previous descriptions of arandaspsids from the Amadeus and Warburton basins of the Northern Territory and New South Wales, respectively, this record extends the paleogeographic range of arandaspids across the hypothetical Ordovician Larapintine Seaway and increases the stratigraphic range of the Order Arandaspidiformes into the Katian. The hard tissue histology of Ritchieichthys nibili confirms the presence of a cellular dentine forming the bulk of the dermal armor ornament in arandaspids, a tissue that had not been directly observed previously, and confirms the presence of largely unconnected osteocytes within the dermal bone that forms the majority of the armor.
ABSTRACT Based upon fragmentary remains of dermal armor, a new form of arandaspid fish, Ritchieic... more ABSTRACT Based upon fragmentary remains of dermal armor, a new form of arandaspid fish, Ritchieichthys nibili, gen et. sp. nov., is described from subsurface core material from the Katian (Late Ordovician) Nibil Formation of the Canning Basin, Western Australia. Ritchieichthys nibili represents the first documented record of a fish from the Ordovician of the Canning Basin. Allied to the previous descriptions of arandaspsids from the Amadeus and Warburton basins of the Northern Territory and New South Wales, respectively, this record extends the paleogeographic range of arandaspids across the hypothetical Ordovician Larapintine Seaway and increases the stratigraphic range of the Order Arandaspidiformes into the Katian. The hard tissue histology of Ritchieichthys nibili confirms the presence of a cellular dentine forming the bulk of the dermal armor ornament in arandaspids, a tissue that had not been directly observed previously, and confirms the presence of largely unconnected osteocytes within the dermal bone that forms the majority of the armor.
Measured lithostratigraphic sections of the classic Permian–Triassic non-marine transitional sequ... more Measured lithostratigraphic sections of the classic Permian–Triassic non-marine transitional sequences covering the upper Quanzijie, Wutonggou, Guodikeng and lower Jiucaiyuan Formations at Dalongkou and Lucaogou, Xinjiang Province, China are presented. These measured sections form the framework and reference sections for a range of multi-disciplinary studies of the P–T transition in this large ancient lake basin, including palynostratigraphy, vertebrate biostratigraphy, chemostratigraphy and magnetostratigraphy. The 121 m thick Wutonggou Formation at Dalongkou includes 12 sandstone units ranging in thickness from 0.5 to 10.5 m that represent cyclical coarse terrigenous input to the lake basin during the Late Permian. The rhythmically-bedded, mudstone-dominated Guodikeng Formation is 197 m and 209 m thick on the north and south limbs of the Dalongkou anticline, respectively, and 129 m thick at Lucaogou. Based on limited palynological data, the Permian–Triassic boundary was previously placed approximately 50 m below the top of this formation at Dalongkou. This boundary does not coincide with any mappable lithologic unit, such as the basal sandstones of the overlying Jiucaiyuan Formation, assigned to the Early Triassic. The presence of multiple organic d13C-isotope excursions, mutant pollen, and multiple algal and conchostracan blooms in this formation, together with Late Permian palynomorphs, suggests that the Guodikeng Formation records multiple climatic perturbation signals representing environmental stress during the late Permian mass extinction interval. The overlap between the vertebrates Dicynodon and Lystrosaurus in the upper part of this formation, and the occurrence of late Permian spores and the latest Permian to earliest Triassic megaspore Otynisporites eotriassicus is consistent with a latest Permian age for at least part of the Guodikeng Formation. Palynostratigrahic placement of the Permian–Triassic boundary in the Junggar Basin remains problematic because key miospore taxa, such as Aratrisporites spp. are not present. Palynomorphs from the Guodikeng are assigned to two assemblages; the youngest, from the upper 100 m of the formation (and the overlying Jiucaiyuan Formation), contains both typical Permian elements and distinctive taxa that elsewhere are known from the Early Triassic of Canada, Greenland, Norway, and Russia. The latter include spores assigned to Pechorosporites disertus, Lundbladispora foveota, Naumovaspora striata, Decussatisporites mulstrigatus and Leptolepidites jonkerii. While the presence of Devonian and Carboniferous spores and Early Permian pollen demonstrate reworking is occurring in the Guodikeng assemblages, the sometimes common occurrence of Scutasporites sp. cf. Scutasporites unicus, and other pollen, suggests that the Late Permian elements are in place, and that the upper assemblage derives from a genuine transitional flora of Early Triassic aspect. In the Junggar Basin, biostratigraphic data and magnetostratigraphic data indicate that the Permian–Triassic boundary (GSSP Level) is in the middle to upper Guodikeng Formation and perhaps as high as the formational contact with the overlying Jiucaiyuan Formation.
The Early Triassic Induan–Olenekian Stage boundary (Dienerian–Smithian sub-stage boundary) has be... more The Early Triassic Induan–Olenekian Stage boundary (Dienerian–Smithian sub-stage boundary) has been identified at a depth of 2719.25 m in the petroleum exploration well Senecio-1 located in the northern Perth Basin,Western Australia. Conodont faunas represent three conodont zones in ascending order, the Neospathodus dieneri Zone, the Neospathodus waageni eowaageni Zone and the Neospathodus waageni waageni Zone. The Induan–Olenekian (Dienerian–Smithian) boundary is placed at the base of the Neospathodus waageni eowaageni Zone equivalent to the first appearance of Neospathodus ex. gr. waageni utilised elsewhere and adopted by the IUGS ICS Triassic Subcommission to define the base of the Olenekian. Bulk kerogen δ13C carbon isotopes define a positive peak of c. 4 per mille that essentially coincides with the Induan–Olenekian boundary as seen in proposed Global Stratotype Sections and Points (GSSPs) in South China and Spiti, India demonstrating the global utility of this level for correlation. An anoxic zone is recognised in the lower part of the Senecio-1 core and the upper limit of this zone is dated as late Induan (late Dienerian). Temporal and spatialmapping of marine anoxia and dysoxia globally demonstrates that pulses of dysoxia/anoxia affected shallow-marine zones at different times in different locations. Dysoxia/anoxia in the shallow-marine environment appeared in the latest Permian at the extinction level, later than in the deep-marine environment, and appears to be largely restricted to the Induan (Griesbachian and Dienerian) and early Olenekian (Smithian). Temporally and geographically restricted upwelling of an oxygenminimum zone into the ocean surface layer due to environmental perturbations including extreme global warming, increased terrestrial chemical weathering intensity and continental erosion, sea level rise, and changes in marine nutrient inventories and productivity rates, is interpreted as a likely cause of observed variation in shallow-marine dysoxia/anoxia in the Early Triassic.
The marine conodont fossil species, Hindeodus changxingensis Wang, that has a distinctive morphol... more The marine conodont fossil species, Hindeodus changxingensis Wang, that has a distinctive morphology, is restricted to a very narrow stratigraphic interval essentially from the Permian–Triassic extinction event through the internationally recognized boundary and into the very earliest Triassic. The species is geographically widespread in the Tethyan Region, from Italy to South China, and serves as a characteristic index fossil to reliably identify this short but critical interval that encompasses the greatest mass extinction of life on earth and the boundary between the Paleozoic and Mesozoic Eras.
ABSTRACT Based upon fragmentary remains of dermal armor, a new form of arandaspid fish, Ritchieic... more ABSTRACT Based upon fragmentary remains of dermal armor, a new form of arandaspid fish, Ritchieichthys nibili, gen et. sp. nov., is described from subsurface core material from the Katian (Late Ordovician) Nibil Formation of the Canning Basin, Western Australia. Ritchieichthys nibili represents the first documented record of a fish from the Ordovician of the Canning Basin. Allied to the previous descriptions of arandaspsids from the Amadeus and Warburton basins of the Northern Territory and New South Wales, respectively, this record extends the paleogeographic range of arandaspids across the hypothetical Ordovician Larapintine Seaway and increases the stratigraphic range of the Order Arandaspidiformes into the Katian. The hard tissue histology of Ritchieichthys nibili confirms the presence of a cellular dentine forming the bulk of the dermal armor ornament in arandaspids, a tissue that had not been directly observed previously, and confirms the presence of largely unconnected osteocytes within the dermal bone that forms the majority of the armor.
Abstract Until recently it has been widely accepted that protoliths to metasediments of the Harts... more Abstract Until recently it has been widely accepted that protoliths to metasediments of the Harts Range Metamorphic Complex (central Australia) were deposited prior to c. 1.75 Ga and form part of the Palaeoproterozoic Arunta Inlier. However, new sensitive high-resolution ion microprobe U–Pb analyses of detrital zircon, together with recently published data, suggest that they were deposited coeval with c. 545–520 Ma sediments from the adjacent, little metamorphosed Neoproterozoic to Palaeozoic Centralian Superbasin. Protoliths of ...
Uploads
Papers
at a depth of 2719.25 m in the petroleum exploration well Senecio-1 located in the northern Perth
Basin,Western Australia. Conodont faunas represent three conodont zones in ascending order, the Neospathodus
dieneri Zone, the Neospathodus waageni eowaageni Zone and the Neospathodus waageni waageni Zone. The
Induan–Olenekian (Dienerian–Smithian) boundary is placed at the base of the Neospathodus waageni eowaageni
Zone equivalent to the first appearance of Neospathodus ex. gr. waageni utilised elsewhere and adopted by the
IUGS ICS Triassic Subcommission to define the base of the Olenekian. Bulk kerogen δ13C carbon isotopes define
a positive peak of c. 4 per mille that essentially coincides with the Induan–Olenekian boundary as seen in proposed
Global Stratotype Sections and Points (GSSPs) in South China and Spiti, India demonstrating the global
utility of this level for correlation. An anoxic zone is recognised in the lower part of the Senecio-1 core and the
upper limit of this zone is dated as late Induan (late Dienerian). Temporal and spatialmapping of marine anoxia
and dysoxia globally demonstrates that pulses of dysoxia/anoxia affected shallow-marine zones at different
times in different locations. Dysoxia/anoxia in the shallow-marine environment appeared in the latest Permian
at the extinction level, later than in the deep-marine environment, and appears to be largely restricted to the
Induan (Griesbachian and Dienerian) and early Olenekian (Smithian). Temporally and geographically restricted
upwelling of an oxygenminimum zone into the ocean surface layer due to environmental perturbations including
extreme global warming, increased terrestrial chemical weathering intensity and continental erosion, sea
level rise, and changes in marine nutrient inventories and productivity rates, is interpreted as a likely cause of
observed variation in shallow-marine dysoxia/anoxia in the Early Triassic.
at a depth of 2719.25 m in the petroleum exploration well Senecio-1 located in the northern Perth
Basin,Western Australia. Conodont faunas represent three conodont zones in ascending order, the Neospathodus
dieneri Zone, the Neospathodus waageni eowaageni Zone and the Neospathodus waageni waageni Zone. The
Induan–Olenekian (Dienerian–Smithian) boundary is placed at the base of the Neospathodus waageni eowaageni
Zone equivalent to the first appearance of Neospathodus ex. gr. waageni utilised elsewhere and adopted by the
IUGS ICS Triassic Subcommission to define the base of the Olenekian. Bulk kerogen δ13C carbon isotopes define
a positive peak of c. 4 per mille that essentially coincides with the Induan–Olenekian boundary as seen in proposed
Global Stratotype Sections and Points (GSSPs) in South China and Spiti, India demonstrating the global
utility of this level for correlation. An anoxic zone is recognised in the lower part of the Senecio-1 core and the
upper limit of this zone is dated as late Induan (late Dienerian). Temporal and spatialmapping of marine anoxia
and dysoxia globally demonstrates that pulses of dysoxia/anoxia affected shallow-marine zones at different
times in different locations. Dysoxia/anoxia in the shallow-marine environment appeared in the latest Permian
at the extinction level, later than in the deep-marine environment, and appears to be largely restricted to the
Induan (Griesbachian and Dienerian) and early Olenekian (Smithian). Temporally and geographically restricted
upwelling of an oxygenminimum zone into the ocean surface layer due to environmental perturbations including
extreme global warming, increased terrestrial chemical weathering intensity and continental erosion, sea
level rise, and changes in marine nutrient inventories and productivity rates, is interpreted as a likely cause of
observed variation in shallow-marine dysoxia/anoxia in the Early Triassic.