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Ruhl M, Hesselbo SP, Jenkyns HC, Xu W, Silva RL, Matthews KJ, Mather TA, Mac Niocaill C, Riding JB. Reduced plate motion controlled timing of Early Jurassic Karoo-Ferrar large igneous province volcanism. SCIENCE ADVANCES 2022; 8:eabo0866. [PMID: 36083904 PMCID: PMC9462690 DOI: 10.1126/sciadv.abo0866] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 07/12/2022] [Indexed: 05/24/2023]
Abstract
Past large igneous province (LIP) emplacement is commonly associated with mantle plume upwelling and led to major carbon emissions. One of Earth's largest past environmental perturbations, the Toarcian oceanic anoxic event (T-OAE; ~183 Ma), has been linked to Karoo-Ferrar LIP emplacement. However, the role of mantle plumes in controlling the onset and timing of LIP magmatism is poorly understood. Using global plate reconstruction models and Lower Toarcian sedimentary mercury (Hg) concentrations, we demonstrate (i) that the T-OAE occurred coevally with Karoo-Ferrar emplacement and (ii) that timing and duration of LIP emplacement was governed by reduced Pangean plate motion, associated with a reversal in plate movement direction. This new model mechanistically links Earth's interior and surficial processes, and the mechanism is consistent with the timing of several of the largest LIP volcanic events throughout Earth history and, thus, the timing of many of Earth's past global climate change and mass extinction events.
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Affiliation(s)
- Micha Ruhl
- Department of Geology, Earth Surface Research Laboratory (ESRL) and SFI Research Centre in Applied Geosciences (iCRAG), Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
- Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN, Oxford, UK
| | - Stephen P. Hesselbo
- Camborne School of Mines and Environment and Sustainability Institute, University of Exeter, Penryn Campus, Treliever Road, Penryn, Cornwall TR10 9FE, UK
| | - Hugh C. Jenkyns
- Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN, Oxford, UK
| | - Weimu Xu
- Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN, Oxford, UK
- School of Earth Sciences and SFI Research Centre in Applied Geosciences (iCRAG), University College Dublin, Belfield, Dublin 4, Ireland
| | - Ricardo L. Silva
- Department of Geology, Earth Surface Research Laboratory (ESRL) and SFI Research Centre in Applied Geosciences (iCRAG), Trinity College Dublin, The University of Dublin, College Green, Dublin 2, Ireland
- Department of Earth Sciences, Clayton H. Riddell Faculty of Environment, Earth, and Resources, University of Manitoba, 125 Dysart Road, Winnipeg, R3T 2N2, Canada
| | - Kara J. Matthews
- Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN, Oxford, UK
- Arctic Institute of North America, University of Calgary, 2500 University Drive NW, ES-1040, Calgary, AB T2N 1N4, Canada
| | - Tamsin A. Mather
- Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN, Oxford, UK
| | - Conall Mac Niocaill
- Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN, Oxford, UK
| | - James B. Riding
- British Geological Survey, Keyworth, Nottingham NG12 5GG, UK
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Font E, Duarte LV, Dekkers MJ, Remazeilles C, Egli R, Spangenberg JE, Fantasia A, Ribeiro J, Gomes E, Mirão J, Adatte T. Rapid light carbon releases and increased aridity linked to Karoo–Ferrar magmatism during the early Toarcian oceanic anoxic event. Sci Rep 2022; 12:4342. [PMID: 35288615 PMCID: PMC8921222 DOI: 10.1038/s41598-022-08269-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 03/03/2022] [Indexed: 11/09/2022] Open
Abstract
Large-scale release of isotopically light carbon is responsible for the carbon isotope excursion (CIE) of the Toarcian Oceanic Anoxic Event during the Lower Jurassic. Proposed sources include methane hydrate dissociation, volcanogenic outgassing of carbon dioxide and/or thermogenic methane release from the Karoo‐Ferrar magmatic province (southern Africa). Distinct small-scale shifts superimposed on the long-term CIE have been interpreted as rapid methane pulses linked to astronomically forced climate changes. In the Peniche reference section (Portugal), these small-scale shifts correspond to distinct brownish marly layers featuring markedly high mercury (Hg) and magnetic mineral concentration. Total organic carbon and Hg increase are uncorrelated, which suggests input of Hg into the atmosphere, possibly released after the intrusion of the Karoo-Ferrar sills into organic-rich sediments. Enhanced magnetic properties are associated with the presence of martite, washed-in oxidized magnetite, inferred to be due to increased aridity on the continental hinterland. This study provides strong evidence for a direct link between the Karoo-Ferrar magmatism, the carbon-isotope shifts and the resulting environmental changes.
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Radermacher VJ, Fernandez V, Schachner ER, Butler RJ, Bordy EM, Naylor Hudgins M, de Klerk WJ, Chapelle KE, Choiniere JN. A new Heterodontosaurus specimen elucidates the unique ventilatory macroevolution of ornithischian dinosaurs. eLife 2021; 10:66036. [PMID: 34225841 PMCID: PMC8260226 DOI: 10.7554/elife.66036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 05/24/2021] [Indexed: 01/21/2023] Open
Abstract
Ornithischian dinosaurs were ecologically prominent herbivores of the Mesozoic Era that achieved a global distribution by the onset of the Cretaceous. The ornithischian body plan is aberrant relative to other ornithodiran clades, and crucial details of their early evolution remain obscure. We present a new, fully articulated skeleton of the early branching ornithischian Heterodontosaurus tucki. Phase-contrast enhanced synchrotron data of this new specimen reveal a suite of novel postcranial features unknown in any other ornithischian, with implications for the early evolution of the group. These features include a large, anteriorly projecting sternum; bizarre, paddle-shaped sternal ribs; and a full gastral basket – the first recovered in Ornithischia. These unusual anatomical traits provide key information on the evolution of the ornithischian body plan and suggest functional shifts in the ventilatory apparatus occurred close to the base of the clade. We complement these anatomical data with a quantitative analysis of ornithischian pelvic architecture, which allows us to make a specific, stepwise hypothesis for their ventilatory evolution. The fossilised skeletons of long extinct dinosaurs are more than just stones. By comparing these remains to their living relatives such as birds and crocodiles, palaeontologists can reveal how dinosaurs grew, moved, ate and socialised. Previous research indicates that dinosaurs were likely warm-blooded and also more active than modern reptiles. This means they would have required breathing mechanisms capable of supplying enough oxygen to allow these elevated activity levels. So far, much of our insight into dinosaur breathing biology has been biased towards dinosaur species more closely related to modern birds, such as Tyrannosaurus rex, as well as the long-necked sauropods. The group of herbivorous dinosaurs known as ornithischians, which include animals with head ornamentation, spikes and heavy body armour, like that found in Triceratops and Stegosaurus, have often been overlooked. As a result, there are still significant gaps in ornithischian biology, especially in understanding how they breathed. Radermacher et al. used high-powered X-rays to study a new specimen of the most primitive ornithischian dinosaur, Heterodontosaurus tucki, and discovered that this South African dinosaur has bones researchers did not know existed in this species. These include bones that are part of the breathing system of extant reptiles and birds, including toothpick-shaped bones called gastralia, paired sternal bones and sternal ribs shaped like tennis rackets. Together, these new pieces of anatomy form a complicated chest skeleton with a large range of motion that would have allowed the body to expand during breathing cycles. But this increased motion of the chest was only possible in more primitive ornithischians. More advanced species lost much of the anatomy that made this motion possible. Radermacher et al. show that while the chest was simpler in advanced species, their pelvis was more specialised and likely played a role in breathing as it does in modern crocodiles. This new discovery could inform the work of biologists who study the respiratory diversity of both living and extinct species. Differences in breathing strategies might be one of the underlying reasons that some lineages of animals go extinct. It could explain why some species do better than others under stressful conditions, like when the climate is warmer or has less oxygen.
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Affiliation(s)
- Viktor J Radermacher
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, United States
| | - Vincent Fernandez
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,European Synchrotron Radiation Facility, Grenoble, France.,Natural History Museum, Imaging and Analysis Centre, London, United Kingdom
| | - Emma R Schachner
- Department of Cell Biology & Anatomy, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, United States
| | - Richard J Butler
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Emese M Bordy
- Department of Geological Sciences, University of Cape Town, Cape Town, South Africa
| | | | - William J de Klerk
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Department of Earth Sciences, Albany Museum, Grahamstown, South Africa
| | - Kimberley Ej Chapelle
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Division of Paleontology, American Museum of Natural History, New York, United States
| | - Jonah N Choiniere
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
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Groundwater of the Modder River Catchment of South Africa: A Sustainability Prediction. WATER 2021. [DOI: 10.3390/w13070936] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This paper presents a spatial interpolation of the hydrological and socioeconomic processes impacting groundwater systems to predict the sustainability of the Modder river catchment of South Africa. These processes are grouped as climatic (factor A), aquifer sustainability (factor D), social-economic and land use (factor B), and the human-induced parameters of rights and equity (factor C). The parameters evaluated for factors A and D included climatic zones, precipitation, sunshine, evapotranspiration, slope, topography, recharge, yields, storativity, aquifer types, and lithology/rock types. Factors B and C included population in the catchment, use per capita, water uses, tariffs and duration of the permits, pump rate per year, number of issued permits per year in the catchment, and number of boreholes in the sub-catchment. This paper, therefore, looks at the impact of the average values of the chosen set of parameters within the given factors A, B, C and D on groundwater in the C52 catchment of the Modder River, as modelled in a sustainability index. C52 is an Upper Orange catchment in South Africa. The results are presented in sustainability maps predicting areas in the catchment with differing groundwater dynamics. The Modder River groundwater sustainability ranged between low and moderate sustainability. The sustainability maps were validated with actual field groundwater recharge and surface water, a comparison between storativity and licensed volume, and a comparison of sustainability scores and storativity. The key finding in this paper will assist groundwater managers and users to adequately plan groundwater resources, especially on licensing and over pumping.
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Abstract
Cyclic variations in Earth’s orbit drive periodic changes in the ocean–atmosphere system at a time scale of tens to hundreds of thousands of years. The Mochras δ13CTOC record illustrates the continued impact of long-eccentricity (405-ky) orbital forcing on the carbon cycle over at least ∼18 My of Early Jurassic time and emphasizes orbital forcing as a driving mechanism behind medium-amplitude δ13C fluctuations superimposed on larger-scale trends that are driven by other variables such as tectonically determined paleogeography and eruption of large igneous provinces. The dataset provides a framework for distinguishing between internal Earth processes and solar-system dynamics as the driving mechanism for Early Jurassic δ13C fluctuations and provides an astronomical time scale for the Sinemurian Stage. Global perturbations to the Early Jurassic environment (∼201 to ∼174 Ma), notably during the Triassic–Jurassic transition and Toarcian Oceanic Anoxic Event, are well studied and largely associated with volcanogenic greenhouse gas emissions released by large igneous provinces. The long-term secular evolution, timing, and pacing of changes in the Early Jurassic carbon cycle that provide context for these events are thus far poorly understood due to a lack of continuous high-resolution δ13C data. Here we present a δ13CTOC record for the uppermost Rhaetian (Triassic) to Pliensbachian (Lower Jurassic), derived from a calcareous mudstone succession of the exceptionally expanded Llanbedr (Mochras Farm) borehole, Cardigan Bay Basin, Wales, United Kingdom. Combined with existing δ13CTOC data from the Toarcian, the compilation covers the entire Lower Jurassic. The dataset reproduces large-amplitude δ13CTOC excursions (>3‰) recognized elsewhere, at the Sinemurian–Pliensbachian transition and in the lower Toarcian serpentinum zone, as well as several previously identified medium-amplitude (∼0.5 to 2‰) shifts in the Hettangian to Pliensbachian interval. In addition, multiple hitherto undiscovered isotope shifts of comparable amplitude and stratigraphic extent are recorded, demonstrating that those similar features described earlier from stratigraphically more limited sections are nonunique in a long-term context. These shifts are identified as long-eccentricity (∼405-ky) orbital cycles. Orbital tuning of the δ13CTOC record provides the basis for an astrochronological duration estimate for the Pliensbachian and Sinemurian, giving implications for the duration of the Hettangian Stage. Overall the chemostratigraphy illustrates particular sensitivity of the marine carbon cycle to long-eccentricity orbital forcing.
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Bordy EM, Rampersadh A, Abrahams M, Lockley MG, Head HV. Tracking the Pliensbachian-Toarcian Karoo firewalkers: Trackways of quadruped and biped dinosaurs and mammaliaforms. PLoS One 2020; 15:e0226847. [PMID: 31995575 PMCID: PMC6988920 DOI: 10.1371/journal.pone.0226847] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 12/05/2019] [Indexed: 11/19/2022] Open
Abstract
The Karoo igneous rocks represent one of the largest continental flood basalt events (by volume) on Earth, and are not normally associated with fossils remains. However, these Pliensbachian–Toarcian lava flows contain sandstone interbeds that are particularly common in the lower part of the volcanic succession and are occasionally fossiliferous. On a sandstone interbed in the northern main Karoo Basin, we discovered twenty-five tridactyl and tetradactyl vertebrate tracks comprising five trackways. The tracks are preserved among desiccation cracks and low-amplitude, asymmetrical ripple marks, implying deposition in low energy, shallow, ephemeral water currents. Based on footprint lengths of 2–14 cm and trackway patterns, the trackmakers were both bipedal and quadrupedal animals of assorted sizes with walking and running gaits. We describe the larger tridactyl tracks as “grallatorid” and attribute them to bipedal theropod dinosaurs, like Coelophysis, a genus common in the Early Jurassic of southern Africa. The smallest tracks are tentatively interpreted as Brasilichnium-like tracks, which are linked to synapsid trackmakers, a common attribution of similar tracks from the Lower to Middle Jurassic record of southern and southwestern Gondwana. The trackway of an intermediate-sized quadruped reveals strong similarities in morphometric parameters to a post-Karoo Zimbabwean trackway from Chewore. These trackways are classified here as a new ichnogenus attributable to small ornithischian dinosaurs as yet without a body fossil record in southern Africa. These tracks not only suggest that dinosaurs and therapsids survived the onset of the Drakensberg volcanism, but also that theropods, ornithischians and synapsids were among the last vertebrates that inhabited the main Karoo Basin some 183 Ma ago. Although these vertebrates survived the first Karoo volcanic eruptions, their rapidly dwindling habitat was turned into a land of fire as it was covered by the outpouring lavas during one of the most dramatic geological episodes in southern Africa.
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Affiliation(s)
- Emese M. Bordy
- Department of Geological Sciences, University of Cape Town, Cape Town, South Africa
- * E-mail:
| | - Akhil Rampersadh
- Department of Geological Sciences, University of Cape Town, Cape Town, South Africa
| | - Miengah Abrahams
- Department of Geological Sciences, University of Cape Town, Cape Town, South Africa
| | - Martin G. Lockley
- Dinosaur Tracks Museum, University of Colorado Denver, Denver, Colorado, United States of America
| | - Howard V. Head
- Department of Geological Sciences, University of Cape Town, Cape Town, South Africa
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Abstract
How cratons, the ancient cores of continents, evolved since their formation over 2.5 Ga ago is debated. Seismic tomography can map the thick lithosphere of cratons, but its resolution is low in sparsely sampled continents. Here we show, using waveform tomography with a large, newly available dataset, that cratonic lithosphere beneath Africa is more complex and fragmented than seen previously. Most known diamondiferous kimberlites, indicative of thick lithosphere at the time of eruption, are where the lithosphere is thin today, implying surprisingly widespread lithospheric erosion over the last 200 Ma. Large igneous provinces, attributed to deep-mantle plumes, were emplaced near all lithosphere-loss locations, concurrently with or preceding the loss. This suggests that the cratonic roots foundered once modified by mantle plumes. Our results imply that the total volume of cratonic lithosphere has decreased since its Archean formation, with the fate of each craton depending on its movements relative to plumes. Cratons represent the ancient cores of continental plates and are generally thought to have been stable since the Archean. Here however, the authors combine seismic analysis with kimberlite data to infer complete destruction of cratonic lithosphere in some places of the African continent.
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Tectono-Thermal Evolution and Morphodynamics of the Central Dronning Maud Land Mountains, East Antarctica, Based on New Thermochronological Data. GEOSCIENCES 2018. [DOI: 10.3390/geosciences8110390] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The lack of preserved Mesozoic–Cenozoic sediments and structures in central Dronning Maud Land has so far limited our understanding of the post-Pan-African evolution of this important part of East Antarctica. In order to investigate the thermal evolution of the basement rocks and place constraints on landscape evolution, we present new low-temperature thermochronological data from 34 samples. Apatite fission track ages range from 280–85 Ma, while single-grain (U-Th)/He ages from apatite and zircon range from 305–15 and 420–340 Ma, respectively. Our preferred thermal history models suggest late Paleozoic–early Mesozoic peneplanation and subsequent burial by 3–6 km of Beacon sediments. The samples experienced no additional burial in the Jurassic, thus the once voluminous continental flood basalts of western Dronning Maud Land did not reach central Dronning Maud Land. Mesozoic–early Cenozoic cooling of the samples was slow. Contrary to western Dronning Maud Land, central Dronning Maud Land lacks a mid-Cretaceous cooling phase. We therefore suggest that the mid-Cretaceous cooling of western Dronning Maud Land should be attributed to the proximity to the collapse of the orogenic plateau at the Panthalassic margin of Gondwana. Cooling rates accelerated considerably with the onset of glaciation at 34 Ma, due to climate deterioration and glacial denudation of up to 2 km.
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McPhee BW, Benson RB, Botha-Brink J, Bordy EM, Choiniere JN. A Giant Dinosaur from the Earliest Jurassic of South Africa and the Transition to Quadrupedality in Early Sauropodomorphs. Curr Biol 2018; 28:3143-3151.e7. [DOI: 10.1016/j.cub.2018.07.063] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 05/30/2018] [Accepted: 07/24/2018] [Indexed: 10/28/2022]
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Sciscio L, Bordy EM, Abrahams M, Knoll F, McPhee BW. The first megatheropod tracks from the Lower Jurassic upper Elliot Formation, Karoo Basin, Lesotho. PLoS One 2017; 12:e0185941. [PMID: 29069093 PMCID: PMC5656318 DOI: 10.1371/journal.pone.0185941] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 09/21/2017] [Indexed: 11/28/2022] Open
Abstract
A palaeosurface with one megatheropod trackway and several theropod tracks and trackways from the Lower Jurassic upper Elliot Formation (Stormberg Group, Karoo Supergroup) in western Lesotho is described. The majority of the theropod tracks are referable to either Eubrontes or Kayentapus based on their morphological characteristics. The larger megatheropod tracks are 57 cm long and have no Southern Hemisphere equivalent. Morphologically, they are more similar to the Early Jurassic Kayentapus, as well as the much younger Upper Cretaceous ichnogenus Irenesauripus, than to other contemporaneous ichnogenera in southern Africa. Herein they have been placed within the ichnogenus Kayentapus and described as a new ichnospecies (Kayentapus ambrokholohali). The tracks are preserved on ripple marked, very fine-grained sandstone of the Lower Jurassic upper Elliot Formation, and thus were made after the end-Triassic mass extinction event (ETE). This new megatheropod trackway site marks the first occurrence of very large carnivorous dinosaurs (estimated body length >8–9 meters) in the Early Jurassic of southern Gondwana, an evolutionary strategy that was repeatedly pursued and amplified in the following ~135 million years, until the next major biotic crisis at the end-Cretaceous.
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Affiliation(s)
- L Sciscio
- Department of Geological Sciences, University of Cape Town, Cape Town, South Africa
| | - E M Bordy
- Department of Geological Sciences, University of Cape Town, Cape Town, South Africa
| | - M Abrahams
- Department of Geological Sciences, University of Cape Town, Cape Town, South Africa
| | - F Knoll
- Fundación Conjunto Paleontológico de Teruel-Dinópolis, Teruel, Spain
| | - B W McPhee
- Departamento de Biologia, FFCLRP, Universidade de São Paulo, São Paulo, Brazil
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Sciscio L, Bordy EM, Reid M, Abrahams M. Sedimentology and ichnology of the Mafube dinosaur track site (Lower Jurassic, eastern Free State, South Africa): a report on footprint preservation and palaeoenvironment. PeerJ 2016; 4:e2285. [PMID: 27635310 PMCID: PMC5012264 DOI: 10.7717/peerj.2285] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 07/03/2016] [Indexed: 11/20/2022] Open
Abstract
Footprint morphology (e.g., outline shape, depth of impression) is one of the key diagnostic features used in the interpretation of ancient vertebrate tracks. Over 80 tridactyl tracks, confined to the same bedding surface in the Lower Jurassic Elliot Formation at Mafube (eastern Free State, South Africa), show large shape variability over the length of the study site. These morphological differences are considered here to be mainly due to variations in the substrate rheology as opposed to differences in the trackmaker's foot anatomy, foot kinematics or recent weathering of the bedding surface. The sedimentary structures (e.g., desiccation cracks, ripple marks) preserved in association with and within some of the Mafube tracks suggest that the imprints were produced essentially contemporaneous and are true dinosaur tracks rather than undertracks or erosional remnants. They are therefore valuable not only for the interpretation of the ancient environment (i.e., seasonally dry river channels) but also for taxonomic assessments as some of them closely resemble the original anatomy of the trackmaker's foot. The tracks are grouped, based on size, into two morphotypes that can be identified as Eubrontes-like and Grallator-like ichnogenera. The Mafube morphotypes are tentatively attributable to large and small tridactyl theropod trackmakers, possibly to Dracovenator and Coelophysis based on the following criteria: (a) lack of manus impressions indicative of obligate bipeds; (b) long, slender-digits that are asymmetrical and taper; (c) often end in a claw impression or point; and (d) the tracks that are longer than broad. To enable high-resolution preservation, curation and subsequent remote studying of the morphological variations of and the secondary features in the tracks, low viscosity silicone rubber was used to generate casts of the Mafube tracks.
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Affiliation(s)
- Lara Sciscio
- Department of Geological Sciences, University of Cape Town , Cape Town , South Africa
| | - Emese M Bordy
- Department of Geological Sciences, University of Cape Town , Cape Town , South Africa
| | - Mhairi Reid
- Department of Geological Sciences, University of Cape Town , Cape Town , South Africa
| | - Miengah Abrahams
- Department of Geological Sciences, University of Cape Town , Cape Town , South Africa
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A new basal sauropod from the pre-Toarcian Jurassic of South Africa: evidence of niche-partitioning at the sauropodomorph-sauropod boundary? Sci Rep 2015; 5:13224. [PMID: 26288028 PMCID: PMC4541066 DOI: 10.1038/srep13224] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 07/21/2015] [Indexed: 11/24/2022] Open
Abstract
The early evolution of sauropod dinosaurs remains poorly understood, with a paucity of unequivocal sauropod taxa known from the first twenty million years of the Jurassic. Recently, the Early Jurassic of South Africa has yielded an assemblage of dental and post-cranial remains displaying a more apomorphic character suite than any other similarly aged sauropodomorph. These remains are interpreted as a new species of basal sauropod and recovered cladistically as the sister taxon to Vulcanodon +more derived Sauropoda, underscoring its importance for our understanding of this pivotal period of sauropod evolution. Key changes in the dentition, axial skeleton and forelimb of this new species suggest a genuine functional distinction occurring at the sauropodiform-sauropod boundary. With reference to these changes, we propose a scenario in which interdependent refinements of the locomotory and feeding apparatus occurred in tandem with, or were effected by, restrictions in the amount of vertical forage initially available to the earliest sauropods. The hypothesized instance of niche-partitioning between basal sauropodan taxa and higher-browsing non-sauropodan sauropodomorphs may partially explain the rarity of true sauropods in the basal rocks of the Jurassic, while having the added corollary of couching the origins of Sauropoda in terms of an ecologically delimited ‘event’.
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Taylor ML, Rogers AD. Evolutionary dynamics of a common sub-Antarctic octocoral family. Mol Phylogenet Evol 2014; 84:185-204. [PMID: 25481103 DOI: 10.1016/j.ympev.2014.11.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 09/23/2014] [Accepted: 11/11/2014] [Indexed: 10/24/2022]
Abstract
Sequence data were obtained for five different loci, both mitochondrial (cox1, mtMutS, 16S) and nuclear (18S, 28S rDNA), from 64 species representing 25 genera of the common deep-sea octocoral family Primnoidae. We tested the hypothesis that Primnoidae have an Antarctic origin, as this is where they currently have high species richness, using Maximum likelihood and Bayesian inference methods of phylogenetic analysis. Using a time-calibrated molecular phylogeny we also investigated the time of species radiation in sub-Antarctic Primnoidae. Our relatively wide taxon sampling and phylogenetic analysis supported Primnoidae as a monophyletic family. The base of the well-supported phylogeny was Pacific in origin, indicating Primnoidae sub-Antarctic diversity is a secondary species radiation. There is also evidence for a subsequent range extension of sub-Antarctic lineages into deep-water areas of the Indian and Pacific Oceans. Conservative and speculative fossil-calibration analyses resulted in two differing estimations of sub-Antarctic species divergence times. Conservative analysis suggested a sub-Antarctic species radiation occurred ∼52MYA (95% HPD: 36-73MYA), potentially before the opening of the Drake Passage and Antarctic Circumpolar Current (ACC) formation (41-37MYA). Speculative analysis pushed this radiation back into the late Jurassic, 157MYA (95% HPD: 118-204MYA). Genus-level groupings were broadly supported in this analysis with some notable polyphyletic exceptions: Callogorgia, Fanellia, Primnoella, Plumarella, Thouarella. Molecular and morphological evidence supports the placement of Tauroprimnoa austasensis within Dasystenella and Fannyella kuekenthali within Metafannyella.
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Affiliation(s)
- Michelle L Taylor
- Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK.
| | - Alex D Rogers
- Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK
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15
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Kent DV, Irving E. Influence of inclination error in sedimentary rocks on the Triassic and Jurassic apparent pole wander path for North America and implications for Cordilleran tectonics. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jb007205] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Schaef H, McGrail B, Owen A. Basalt- CO2–H2O interactions and variability in carbonate mineralization rates. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.egypro.2009.02.320] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Affiliation(s)
- Matthias König
- Alfred Wegener Institute for Polar and Marine Research; Bremerhaven Germany
| | - Wilfried Jokat
- Alfred Wegener Institute for Polar and Marine Research; Bremerhaven Germany
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Kemp DB, Coe AL, Cohen AS, Schwark L. Astronomical pacing of methane release in the Early Jurassic period. Nature 2005; 437:396-9. [PMID: 16163353 DOI: 10.1038/nature04037] [Citation(s) in RCA: 335] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Accepted: 07/04/2005] [Indexed: 11/09/2022]
Abstract
A pronounced negative carbon-isotope (delta13C) excursion of approximately 5-7 per thousand (refs 1-7) indicates the occurrence of a significant perturbation to the global carbon cycle during the Early Jurassic period (early Toarcian age, approximately 183 million years ago). The rapid release of 12C-enriched biogenic methane as a result of continental-shelf methane hydrate dissociation has been put forward as a possible explanation for this observation. Here we report high-resolution organic carbon-isotope data from well-preserved mudrocks in Yorkshire, UK, which demonstrate that the carbon-isotope excursion occurred in three abrupt stages, each showing a shift of -2 per thousand to -3 per thousand. Spectral analysis of these carbon-isotope measurements and of high-resolution carbonate abundance data reveals a regular cyclicity. We interpret these results as providing strong evidence that methane release proceeded in three rapid pulses and that these pulses were controlled by astronomically forced changes in climate, superimposed upon longer-term global warming. We also find that the first two pulses of methane release each coincided with the extinction of a large proportion of marine species.
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Affiliation(s)
- David B Kemp
- Department of Earth Sciences, Centre for Earth, Planetary, Space & Astronomical Research, The Open University, Milton Keynes MK7 6AA, UK.
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19
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Jahn BM. The Central Asian Orogenic Belt and growth of the continental crust in the Phanerozoic. ACTA ACUST UNITED AC 2004. [DOI: 10.1144/gsl.sp.2004.226.01.05] [Citation(s) in RCA: 467] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractAsia is the world’s largest composite continent, comprising numerous old cratonic blocks and young mobile belts. During the Phanerozoic it was enlarged by successive accretion of dispersed Gondwana-derived terranes. The opening and closing of palaeo-oceans would have inevitably produced a certain amount of fresh mantle-derived juvenile crust. The Central Asian Orogenic Belt (CAOB), otherwise known as the Altaid tectonic collage, is now celebrated for its accretionary tectonics and massive juvenile crustal production in the Phanerozoic. It is composed of a variety of tectonic units, including Precambrian microcontinental blocks, ancient island arcs, ocean island, accretionary complexes, ophiolites and passive continental margins. Yet, the most outstanding feature is the vast expanse of granitic intrusions and their volcanic equivalents. Since granitoids are generated in lower-to-middle crustal conditions, they are used to probe the nature of their crustal sources, and to evaluate the relative contribution of juvenile v. recycled crust in the orogenic belts. Using the Nd-Sr isotope tracer technique, the majority of granitoids from the CAOB can be shown to contain high proportions (60 to 100%) of the mantle component in their generation. This implies an important crustal growth in continental scale during the period of 500–100 Ma. The evolution of the CAOB undoubtedly involved both lateral and vertical accretion of juvenile material. The lateral accretion implies stacking of arc complexes, accompanied by amalgamation of old microcontinental blocks. Parts of the accreted arc assemblages were later converted into granitoids via underplating of basaltic magmas. The emplacement of large volumes of post-accretionary alkaline and peralkaline granites was most likely achieved by vertical accretion through a series of processes, including underplating of basaltic magma, mixing of basaltic liquid with lower-crustal rocks, partial melting of the mixed lithologies leading to generation of granitic liquids, and followed by fractional crystallization. The recognition of vast juvenile terranes in the Canadian Cordillera, the western US, the Appalachians and the Central Asian Orogenic Belt has considerably changed our view on the growth rate of the continental crust in the Phanerozoic.
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Affiliation(s)
- Bor-Ming Jahn
- Department of Geosciences, National Taiwan University
P.O. Box 13-318, Taipei 106, Taiwan
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20
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Jamtveit B, Svensen H, Podladchikov YY, Planke S. Hydrothermal vent complexes associated with sill intrusions in sedimentary basins. ACTA ACUST UNITED AC 2004. [DOI: 10.1144/gsl.sp.2004.234.01.15] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractSubvolcanic intrusions in sedimentary basins cause strong thermal perturbations and frequently cause extensive hydrothermal activity. Hydrothermal vent complexes emanating from the tips of transgressive sills are observed in seismic profiles from the Northeast Atlantic margin, and geometrically similar complexes occur in the Stormberg Group within the Late Carboniferous-Middle Jurassic Karoo Basin in South Africa. Distinct features include inward-dipping sedimentary strata surrounding a central vent complex, comprising multiple sandstone dykes, pipes, and hydrothermal breccias. Theoretical arguments reveal that the extent of fluid-pressure build-up depends largely on a single dimensionless number (Ve) that reflects the relative rates of heat and fluid transport. For Ve >> 1, ‘explosive’ release of fluids from the area near the upper sill surface triggers hydrothermal venting shortly after sill emplacement. In the Karoo Basin, the formation of shallow (< 1 km) sandstone-hosted vents was initially associated with extensive brecciation, followed by emplacement of sandstone dykes and pipes in the central parts of the vent complexes. High fluid fluxes towards the surface were sustained by boiling of aqueous fluids near the sill. Both the sill bodies and the hydrothermal vent complexes represent major perturbations of the permeability structure of the sedimentary basin, and are likely to have long time-scale effects on its hydrogeological evolution.
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Affiliation(s)
- Bjørn Jamtveit
- Physics of Geological Processes (PGP), University of Oslo
PO Box 1048 Blindern, 0316 Oslo, Norway
| | - Henrik Svensen
- Physics of Geological Processes (PGP), University of Oslo
PO Box 1048 Blindern, 0316 Oslo, Norway
| | - Yuri Y. Podladchikov
- Physics of Geological Processes (PGP), University of Oslo
PO Box 1048 Blindern, 0316 Oslo, Norway
| | - Sverre Planke
- Physics of Geological Processes (PGP), University of Oslo
PO Box 1048 Blindern, 0316 Oslo, Norway
- Volcanic Basin Petroleum Research, Oslo Research Park
Gaustadalleen 21, 0349 Oslo, Norway
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Zhang X, Luttinen AV, Elliot DH, Larsson K, Foland KA. Early stages of Gondwana breakup: The40Ar/39Ar geochronology of Jurassic basaltic rocks from western Dronning Maud Land, Antarctica, and implications for the timing of magmatic and hydrothermal events. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2001jb001070] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- X. Zhang
- Department of Geological Sciences; The Ohio State University; Columbus Ohio USA
| | | | - D. H. Elliot
- Department of Geological Sciences; The Ohio State University; Columbus Ohio USA
| | - K. Larsson
- Department of Geology; University of Lund; Lund Sweden
| | - K. A. Foland
- Department of Geological Sciences; The Ohio State University; Columbus Ohio USA
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van der Beek P, Summerfield MA, Braun J, Brown RW, Fleming A. Modeling postbreakup landscape development and denudational history across the southeast African (Drakensberg Escarpment) margin. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001jb000744] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Peter van der Beek
- Laboratoire de Géodynamique des Chaînes Alpines; Université Joseph Fourier; Grenoble France
| | | | - Jean Braun
- Research School of Earth Sciences; Australian National University; Canberra Australia
| | - Roderick W. Brown
- School of Earth Sciences; University of Melbourne; Melbourne Victoria Australia
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Brown RW, Summerfield MA, Gleadow AJW. Denudational history along a transect across the Drakensberg Escarpment of southern Africa derived from apatite fission track thermochronology. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001jb000745] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Roderick W. Brown
- School of Earth Sciences; University of Melbourne; Melbourne Victoria Australia
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Bauer K, Neben S, Schreckenberger B, Emmermann R, Hinz K, Fechner N, Gohl K, Schulze A, Trumbull RB, Weber K. Deep structure of the Namibia continental margin as derived from integrated geophysical studies. ACTA ACUST UNITED AC 2000. [DOI: 10.1029/2000jb900227] [Citation(s) in RCA: 175] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
In the Jurassic period, the Early Toarcian oceanic anoxic event (about 183 million years ago) is associated with exceptionally high rates of organic-carbon burial, high palaeotemperatures and significant mass extinction. Heavy carbon-isotope compositions in rocks and fossils of this age have been linked to the global burial of organic carbon, which is isotopically light. In contrast, examples of light carbon-isotope values from marine organic matter of Early Toarcian age have been explained principally in terms of localized upwelling of bottom water enriched in 12C versus 13C (refs 1,2,5,6). Here, however, we report carbon-isotope analyses of fossil wood which demonstrate that isotopically light carbon dominated all the upper oceanic, biospheric and atmospheric carbon reservoirs, and that this occurred despite the enhanced burial of organic carbon. We propose that--as has been suggested for the Late Palaeocene thermal maximum, some 55 million years ago--the observed patterns were produced by voluminous and extremely rapid release of methane from gas hydrate contained in marine continental-margin sediments.
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Marzoli A, Renne PR, Piccirillo EM, Ernesto M, Bellieni G. Extensive 200-million-year-Old continental flood basalts of the central atlantic magmatic province. Science 1999; 284:616-8. [PMID: 10213679 DOI: 10.1126/science.284.5414.616] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Central Atlantic Magmatic Province (CAMP) is defined by tholeiitic basalts that crop out in once-contiguous parts of North America, Europe, Africa, and South America and is associated with the breakup of Pangea. 40Ar/39Ar and paleomagnetic data indicate that CAMP magmatism extended over an area of 2.5 million square kilometers in north and central Brazil, and the total aerial extent of the magmatism exceeded 7 million square kilometers in a few million years, with peak activity at 200 million years ago. The magmatism coincided closely in time with a major mass extinction at the Triassic-Jurassic boundary.
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Affiliation(s)
- A Marzoli
- Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, USA. Dipartimento di Scienze della Terra, Universita di Trieste, via Weiss 8, 34127 Trieste, Italy. Department of Geology and Geophysics, University of California, Berkeley
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Stanistreet IG, Stollhofen H. Onshore equivalents of the main Kudu gas reservoir in Namibia. ACTA ACUST UNITED AC 1999. [DOI: 10.1144/gsl.sp.1999.153.01.21] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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