The evolution of the Australian flora: fossil evidence
Reference:
Hill, R.S., Truswell, E.M., McLoughlin, S. & Dettmann, M.E. 1999. The evolution of the Australian flora: fossil evidence. Flora of Australia, 2nd Edition, 1 (Introduction): 251-320.
The prehistory of the Australian vegetation is summarized – from the earliest traces of life in the Precambrian to the... more The prehistory of the Australian vegetation is summarized – from the earliest traces of life in the Precambrian to the events of the Cenozoic that shaped the continent’s modern flora. Australia’s oldest land plants appear in the Silurian with the rise of the lycophyte-dominated Baragwanathia flora. A succession of late Palaeozoic and Mesozoic pteridophyte- and gymnosperm-dominated floras followed, successive floras being punctuated by phases of major climate change and/or global mass-extinction events. For much of its Phenerozoic history, Australia has been part of the supercontinent Gondwana, thus it has shared broadly similar floras with the other Southern Hemisphere continents. The rise of the angiosperms in the Early Cretaceous was coincident with or slightly preceded the later stages of Gondwanan breakup. The modern angiosperm-dominated flora, therefore, developed during progressive isolation of Australia and its eventual collision with landmasses of southeast Asia. This history of isolation and amalgamation, together with the great climatic changes that have affected the continent over the past 100 million years, has set up intriguing scenarios for explaining the past and present distribution of a broad range of Australia’s plant taxa.
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Seen by:Cainozoic euphorbiacean wood from the Canning Basin, Western Australia
Reference:
Bamford, M. & McLoughlin, S., 2000. Cainozoic euphorbiacean wood from the Canning Basin, Western Australia. Alcheringa 24, 243-256.
A new species of fossil wood is described, Bridelioxylon canningense Bamford & McLoughlin, belonging to the... more A new species of fossil wood is described, Bridelioxylon canningense Bamford & McLoughlin, belonging to the Phyllanthoideae group of the Euphorbiaceae. The woods occur in indurated sandstones and conglomerates preserved in palaeochannels incised into the Upper Permian Condren Sandstone in the Landrigan Cliffs, northern Canning Basin, Western Australia. Based on the presence of the dicotyledonous woods and the geomorphological setting of the palaeochannel, a Palaeogene age is suggested for the host rocks. This is the first record of fossil euphorbiacean wood in Australia; pollen has been previously recorded. The fossil wood is most closely comparable to extant members of Bridelia that currently occupy the warmer and wetter parts of Australia.
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Seen by:The Australasian Cretaceous scene
Reference:
McLoughlin, S. & Kear, B.P., 2010. The Australasian Cretaceous scene. Alcheringa 34, 197–203.
The Cretaceous saw dramatic changes in the tectonic setting, landscape and biodiversity of Australasia. Continental... more The Cretaceous saw dramatic changes in the tectonic setting, landscape and biodiversity of Australasia. Continental fragmentation, marine transgression, the rise of ‘modern’ faunas and floras, and the Cretaceous–Paleogene mass extinction represent key events that set the stage for future evolution of this region’s insular Cenozoic biotas. Australasia’s rich but scattered Cretaceous fossil record also provides a rare glimpse into austral high-latitude life and environments throughout the breakup phase of southeastern Gondwana.
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Seen by:The influence of geological fabric and scale on drainage pattern analysis in a catchment of metamorphic terrain: Laceys Creek, southeast Queensland, Australia
Reference:
Hodgkinson, J.H., McLoughlin, S. & Cox, M.E. 2006. The influence of structural grain on drainage in a metamorphic sub-catchment: Laceys Creek, southeast Queensland, Australia. Geomorphology, 81: 394-407.
The relationship between geological fabric and drainage patterns in the 81.8 km2 Laceys Creek sub-catchment of the... more
The relationship between geological fabric and drainage patterns in the 81.8 km2 Laceys Creek sub-catchment of the North Pine River catchment, southeast Queensland, Australia, is analysed using a new channel–ordination system. The Laceys Creek catchment is situated on the South D'Aguilar Block, which underwent metamorphism, faulting and uplift from the Late Carboniferous to Late Triassic. The catchment drains exposures of two main rock units, the Neranleigh–Fernvale Beds and the Bunya Phyllite. Both units are composed of metamorphosed deep-sea sediments that accumulated as an accretionary wedge during late Palaeozoic subduction of the palaeo-Pacific plate under the eastern margin of the Australian craton. The new channel ordination system used in this study allows improved classification of stream segments of equal prominence or rank in comparison to previous schemes. A 10 m contour digital elevation model (DEM) was produced within which drainage channels were digitised. Planar geological features, including bedding, faults, joints and cleavage, were mapped in the field and collated with data from previous geological mapping programs.
Regional and local trends of geological fabric are reflected in the variable orientation of channels of different rank in the catchment. Cleavage and fractures are the dominant planar features of the Bunya Phyllite and these correlate most closely with the orientation of middle-order incised stream segments. In contrast, middle-order channels on the Neranleigh–Fernvale Beds most closely correlate with bedding, which dominates the fabric of this unit. Although anthropogenic factors exert local influence and climatic processes exert broad influence on the catchment, this study focuses on structural and lithological fabrics, which are the apparent dominant controls on middleorder channel orientations. Identification of congruent patterns between bedrock fabric and channel ranks is variable, depending on the scale and number of channels included in the analysis. Many low-rank channels correspond closely to the orientation of fine-scale bedding and foliation and these influencesmay not be detected by coarse-scalemapping.Understanding the extent of geological controls on the morphology of a catchment may assist geo-hazard identification, land-use planning and civil-engineering projects.
Coupling mineral analysis with conceptual groundwater flow modelling: The source and fate of iron, aluminium and manganese in a back-barrier island
Reference:
Hodgkinson, J., Cox, M.E. & McLoughlin, S., 2008. Coupling mineral analysis with conceptual groundwater flow modelling: The source and fate of iron, aluminium and manganese in a back-barrier island. Chemical Geology 251: 77-98.
Mineral and aqueous geochemical data are combined with a conceptual groundwater flow model, to establish the origin... more Mineral and aqueous geochemical data are combined with a conceptual groundwater flow model, to establish the origin and fate of iron, aluminium and manganese in the groundwater system of a small backbarrier island. The flow model domain consists of an unconfined island fresh groundwater lens overlying a semi-confined hypersaline aquifer. The two aquifers are separated by a discontinuous, clay-rich aquitard and both contain diffusion governed variable density flow fields. High concentrations of dissolved iron and manganese are associated with brackish to hypersaline groundwater, although there is no systematic relationship with salinity. Calculation of S2_/SO4 2_ and Fe2+/Fe3+ redox couples and the results of thermodynamic modelling show that redox disequilibrium in the groundwater is widespread. Groundwater samples containing aqueous sulphide and ferric iron complexes are supersaturated with respect to pyrite, goethite and haematite but the prevailing state of redox disequilibrium controls mineral dissolution and precipitation. Aqueous iron in the deeper regions of both aquifers is derived from the dissolution of iron oxide–hydroxides in lateritic palaeosols controlled by seasonal fluctuations in groundwater redox state. Aqueous manganese is potentially derived from the dissolution of ilmenite and amorphous oxide– hydroxides. The oxidation of iron sulphides contributes to the aqueous iron concentration and sulphuric acid production in the shallow groundwater. The solubility of aluminium is also limited by this process, governed by acidity regulation. A significant proportion of aqueous iron is transmitted from the semi-confined to the overlying unconfined aquifer through discontinuities in the aquitard layer. Movement of metals in solution outside the island groundwater system is restricted by the presence of diffusion boundaries within variable density transition zones.
Early Cretaceous megaspore assemblages from southeastern Australia
Reference:
Tosolini, A.-M., McLoughlin, S. & Drinnan, A.N. 2002. Early Cretaceous megaspore assemblages from southeastern Australia. Cretaceous Research, 23: 807-844.
Twenty-nine megaspore species including six new taxa (Bacutriletes otwayensis sp. nov., Erlansonisporites cerebrus sp.... more Twenty-nine megaspore species including six new taxa (Bacutriletes otwayensis sp. nov., Erlansonisporites cerebrus sp. nov., Erlansonisporites decisum sp. nov., Hughesisporites coronatus sp. nov., Hughesisporites dettmanniae sp. nov., and Verrutriletes depressus sp. nov.) are documented from Aptian and Albian strata of the Gippsland and Otway basins, southeastern Australia. Together with six taxa known only from underlying Neocomian strata, these megaspores are used to establish four provisional biozones for the Lower Cretaceous that complement existing biostratigraphic schemes based on miospores and plant macrofossils. Megaspores are best represented in silty floodbasin facies and it is likely that the parent plants predominantly occupied moist understorey to fully aquatic habitats on the floodplain. Megaspores are sparsely represented in most other fluvial facies chiefly due to reworking of floodbasin sediments into higher energy channel and crevasse deposits. The relatively high diversity of lycophyte and fern megaspores contrasts with the scarcity of these plant groups in macrofossil assemblages. The megaspore record suggests that heterosporous cryptogams may have been significantly more prominent in the vegetation of this region than previously suggested. Several megaspores from southeastern Australia are closely comparable to forms from India and Argentina indicating broad similarities between Early Cretaceous heterosporous fern and lycophyte communities across Gondwana. These similarities also suggest that megaspores may be useful for inter-continental biostratigraphic correlation.
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Seen by:Australian Jurassic sedimentary and fossil successions: current work and future prospects for marine and non-marine correlation
Turner, S., Bean, L.B., Dettmann, M., McKellar, J.L., McLoughlin, S. & Thulborn, T., 2009: Australian Jurassic sedimentary and fossil successions: current work and future prospects for marine and non-marine correlation. GFF 131, 49–70.
Strata of Jurassic age occur extensively across onshore Australia, but they are predominantly of non-marine origin.... more Strata of Jurassic age occur extensively across onshore Australia, but they are predominantly of non-marine origin. Marine Jurassic strata have only limited onshore exposure in northwestern and central-western Australia, with thick marine sequences lying offshore on the North West Shelf. The richest petroleum province in Australia is located at the shelf’s southern end, where the Dingo Claystone represents an important source rock for oil and gas. By and large, non-marine deposits, including economic coals, are distributed in the eastern states. Jurassic stage boundaries, in the main, are poorly constrained with respect to the Australian sedimentary succession. New work on microfossils, plants, fish, and zircon dating is providing a basis for improved correlation across Australian basins, with overseas successions, and recent international IUGS geologic timescales.
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Seen by:The Jurassic flora of Western Australia
Reference:
McLoughlin, S. & Pott, C., 2009: The Jurassic flora of Western Australia. GFF 131, 113–136.
Jurassic plant remains in Western Australia are sparse but small assemblages of impression fossils have been deposited... more Jurassic plant remains in Western Australia are sparse but small assemblages of impression fossils have been deposited in the collections of the Australian Museum, Sydney, over the past century. They reveal the presence of ?Matoniaceae and Cladophlebis sp. from the Cockleshell Gully Formation (Toarcian–Aalenian), Zamites sp. from the Dingo Claystone (Middle to Upper Jurassic), and Elatocladus confertus (Oldham & Morris) Halle, Pagiophyllum amanguanus sp. nov., ?microsporangiate cones, Otozamites bengalensis Oldham & Morris, Otozamites linearis Halle, Otozamites sp. and Ptilophyllum cutchense Morris from the Yarragadee Formation (Late Jurassic). The assemblages show links to eastern Australian, Indian and Antarctic floras of Early Jurassic to Early Cretaceous age. The macrofloras generally support previous palynological dating of the host units, but also indicate broad (generic-level) similarities between Jurassic and Early Cretaceous floras across Gondwana. The macrofloras have no strong taxonomic or morphological signatures indicative of either aridity or humidity but the bennettitaleans have leaves intermediate in size between low and high latitude mid-Mesozoic assemblages, which favours previous palaeogeographic placements of Western Australia in the mesothermal middle-latitude province in the Jurassic.
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Seen by:Anatomically preserved Glossopteris leaves from the Bowen and Sydney basins, Australia
Reference:
Pigg, K.B. & McLoughlin, S. 1997. Anatomically preserved Glossopteris leaves from the Bowen and Sydney basins, Australia. Review of Palaeobotany and Palynology, 97: 339-359.
Anatomically preserved vegetative Glossopteris leaves in silicified peat deposits of Late Permian age are described... more Anatomically preserved vegetative Glossopteris leaves in silicified peat deposits of Late Permian age are described from the Bowen Basin of Queensland and the Sydney Basin of New South Wales, Australia. Glossopteris homevalensis Pigg et McLoughlin, sp. nov., a distinctive new species from the Fort Cooper Coal Measures, Bowen Basin, is characterized by mesarch vascular bundles with parenchymatous bundle sheaths, a prominent midrib, the occasional presence of secondary vascular tissues, a differentiated mesophyll, an ad- and abaxial hypodermis of isodiametric cuboidal cells with abundant fibers, epidermal cells with sinuous anticlinal margins and simple, slightly sunken stomata. Anatomically preserved leaves similar to G. schopfii Pigg, originally described from the central Transantarctic Mountains of Antarctica are also documented from the Bowen and Sydney basins. Those from the Burngrove Formation (Bowen Basin) differ slightly from Antarctic G. schopfii in size, and possess more numerous bundle sheath fibers and sometimes a more pronounced palisade mesophyll. Those from Katoomba (Sydney Basin) are also similar but may differ in some cuticular details. Also occurring in the Katoomba and Burngrove floras are leaves resembling G. skaarensis Pigg, a second species originally described from Antarctica. The presence of G. schopfii and cf. G. skaarensis in Australia as well as in the Transantarctic Mountains demonstrates their widespread distribution in eastern Gondwana. In contrast, the apparent restriction of G. homevalensis to a single locality in the Bowen Basin may reflect a distinct, more local distribution of a floristic assemblage unlike those typical of other Australian and Antarctic floras.
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Seen by:Early Jurassic annelid cocoons from eastern Australia
Reference:
Jansson, I.-M., McLoughlin, S. & Vajda, V., 2008. Early Jurassic annelid cocoons from eastern Australia. Alcheringa 32: 285-296.
A small assemblage of clitellate annelid cocoons (egg cases) is described from the Early Jurassic Marburg Subgroup,... more A small assemblage of clitellate annelid cocoons (egg cases) is described from the Early Jurassic Marburg Subgroup, Clarence-Moreton Basin, eastern Australia. Two complete specimens are preserved on bedding planes, and numerous fragments were recovered from organic residues prepared for mesofossil analysis. The complete specimens are assigned to Burejospermum Krassilov emend. Manum, Bose & Sawyer, 1991, having a well-developed mesh-like hapsine and a solid layer of underlying alytine. The fragments include a form assigned to Dictyothylakos Horst, 1954 emend. Manum, Bose & Sawyer, 1991 having a mesh-like hapsine but lacking an alytine layer. The cocoons are preserved in floodbasin facies represented by leaf-rich, dark shales. Palynological data indicate a Pliensbachian to earliest Toarcian age for the assemblage. Similarities between the new specimens, congeneric material from the Triassic to Neogene of other continents, and modern egg cases highlight the long-term morphological conservatism of clitellate cocoons. The new material extends the distribution of such fossils, which generally have a poor macrofossil record.
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Seen by:Late Permian plant megafossils from the Bowen Basin, Queensland, Australia: Part 2
Reference:
McLoughlin, S. 1994. Late Permian plant megafossils from the Bowen Basin, Queensland, Australia: Part 2. Palaeontographica 231B, 1-29.
Late Permian floras of the Bowen Basin, Queensland, Australia, are dominated by Glossopteris leaves. Ten new species... more Late Permian floras of the Bowen Basin, Queensland, Australia, are dominated by Glossopteris leaves. Ten new species are described herein (viz., Glossopteris acutifolia, G. bifurcata, G. burngrovensis, G. chevronata, G. curvinervosa, G. denisonemis, G. fitzroyensis, G, gladiforma, G. grandis, and G, habenata). Two previously established species (G. browniana BRONGNIART ex BRONGNIART 1831 and G. hucklandensis McLOUGHLIN 1990) are also described. No single character is available to consistently distinguish Glossopteris species. Species recognition depends upon comparison of a suite of leaf shape and venation characters, together with cuticular features and attached fertile organs where they are available. Although past studies have often linked Glossopteris leaves from widely disparate basins into broadly defined species, few of the species described herein appear to be conspecific with forms outside eastern Australia.
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Seen by:Permian sphenophytes from the Collie and Perth Basins, Western Australia
McLoughlin, S., 1992. Permian sphenophytes from the Collie and Perth Basins, Western Australia. Rev. Palaeobot. Palynol.,
75: 153-182.
Lelstotheca lanceolata and Sphenophyllum morganae are newly described from the Irwin River Coal Measures (Artinskian),... more
Lelstotheca lanceolata and Sphenophyllum morganae are newly described from the Irwin River Coal Measures (Artinskian), northern Perth Basin. The distribution of Raniganjia minima Rigby, 1966 is extended to the Muja Member, Collie Coal Measures (Kungurian-Ufimian?), Collie Basin. A large collection of Sphenophyllum rhodesii Rigby, 1966 specimens from the Irwin River Coal Measures has permitted more detailed circumscription of this abundant herbaceous species. Reinterpretation of the morphology of Gondwanophyton daymondii Rigby, 1992 suggests that the plant possessed reniform leaves borne in pairs
at the nodes of slender articulate axes. Bed-transecting, striate, weakly jointed, flanged axes from the Irwin River Coal Measures probably represent subterranean rhizomes associated with Paracalamites australis Rigby, 1966 stems. Tabulation of the distribution of Permian Gondwanic bowmanitaceans indicates that radially symmetrical Sphenophyllum species were predominant in the Early Permian whereas bilaterally symmetrical Trizygia or bifid-leafed Benlightfootia species dominated the Late Permian.
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Seen by:Late Permian glossopterid fructifications from the Bowen and Sydney Basins, eastern Australia
Reference:
McLoughlin, S. 1990. Late Permian glossopterid fructifications from the Bowen and Sydney Basins, eastern Australia. Geobios, 23: 283-297.
The morphology and taxonomy of several glossopterid reproductive structures, from Late Permian nonmarine strata of... more The morphology and taxonomy of several glossopterid reproductive structures, from Late Permian nonmarine strata of eastern Australia, are discussed herein. Plumsteadia jensenii sp. nov. is described from the Black Alley Shale, western Bowen Basin. Plumsteadia microsacca RIGBY, 1963 and five other forms tentatively referred to this genus, are recorded from Late Permian sediments of the western and central Bowen Basin; and Plumsteadia sp. cf. P. ampla (WHITE) RIGBY, 1969 is recorded from coeval sediments of the Sydney Basin. Additionally reported is a single juvenile or degenerate fructification from the Black Alley Shale attached to the midrib of a Glossopteris leaf. The chronological and geographic distribution of Permian Gondwanic fructifications referable to Plumsteadia is tabulated.
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Seen by:Plant fossil distributions in some Australian Permian non-marine sediments
Reference:
McLoughlin, S., 1993. Plant fossil distributions in some Australian Permian non-marine sediments. Sedimentary Geology 85, 601-619.
Plant remains occur in all post-Devonian, lowland, terrestrial depositional systems, with distinctive assemblages... more Plant remains occur in all post-Devonian, lowland, terrestrial depositional systems, with distinctive assemblages characterizing discrete environments. Glossopterid gymnosperms dominate most Australian Permian coal-bearing sediments. Herbaceous pteridophytes, sphenophytes, and lycophytes are best represented in lower deltaic lacustrine and paludal deposits. Non-glossopterid gymnosperms mostly colonized drier floodplain and upland environments and are poorly represented in Australian Permian sequences. Fresh- and brackish-water algae are abundantly preserved in paludal and lacustrine facies in both alluvial and delta plain environments. Seasonal productivity and taphonomic factors undoubtedly influenced the composition of interseam compression/impression floras but integration of information from these assemblages with that from permineralized peats, in-situ coalified plants, and coal maceral and palynological analyses can assist in the interpretation of Australian Permian coal-forming environments and the structure of plant communities.
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Seen by:Late Permian plant megafossils from the Bowen Basin, Queensland, Australia: Part 1
Reference:
McLoughlin, S. 1992. Late Permian plant megafossils from the Bowen Basin, Queensland, Australia: Part 1. Palaeontographica 228B: 105-149.
Permian non-marine strata in the southern Bowen Basin, Queensland, Australia, yield abundant plant megafossils... more Permian non-marine strata in the southern Bowen Basin, Queensland, Australia, yield abundant plant megafossils preserved as impressions, coalified compressions, siliceous petrifactions, and mudstone casts. Plant megafossi1s (excluding glossopterid leaves and fruits) are described from 11 lithostratigraphic units and five subprovinces of the southern Bowen Basin. Several new fossil localities (including a deposit of silicified peat) are described, yielding typical Gondwanic plant assemblages and extending the stratigraphic and geographic ranges of some common pteridophyte and gymnosperm species. New species of gymnospermous seeds (viz., Samaropsis carinata, S. cometensis, S. excellens and S. minniensis) are described. Several plant genera, including Lelstotheca, Puudoctenis, and Pterophyllum, are recorded for the first time from the southern Bowen Basin. Comparison with other Australian and Gondwanic assemblages indicates a Late Permian age for the studied floras.
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Seen by:Late Permian plant megafossils from the Bowen Basin, Queensland, Australia: Part 3
Reference:
McLoughlin, S. 1994. Late Permian plant megafossils from the Bowen Basin, Queensland, Australia: Part 3. Palaeontographica 231B: 31-62.
Glossopterid gymnosperms dominate the Late Permian floras of the Bowen Basin, Queensland, Australia. Seven new species... more Glossopterid gymnosperms dominate the Late Permian floras of the Bowen Basin, Queensland, Australia. Seven new species of Glosopteris (viz., G. indicoides, G. kingii, G. linguiforma, G. plumata, G. rhombimaculata, G. truncata, and G. xiphophylla) are described together with G. rectinervis Dun 1897 emend. Banerjee 1978 and a form comparable to the Antarctic G. schopfii Pigg 1990. Analysis of the distribution of 62 megaplant species recorded from 11 lithological units in the southern Bowen Basin offers the potential for improved phytostratigraphic zonation of the Australian Permian. The megaplant assemblages of the upper Blenheim Subgroup (Back Creek Group) and Blackwater Group, Bowen Basin, are correlated with the floras of the Tomago and Newcastle Coal Measures and their equivalents in the Sydney Basin. Few glossopterid species are shared among the Bowen Basin and extra-Australian basins. The studied megafloras show best intercontinental correlation (via shared glossopterid genera and sphenophyte species) with the Raniganj and Kamthi Formations, India, and Estcourt Formation, South Africa.
Nothofagus plicata (Nothofagaceae), a new deciduous Eocene macrofossil species, from southern continental Australia
Reference:
Scriven, L.J., McLoughlin, S. & Hill, R.S., 1995. Nothofagus plicata (Nothofagaceae), a new deciduous Eocene macrofossil species, from southern continental Australia. Review of Palaeobotany and Palynology 86, 199–209.
A new leaf species of Nothofagaceae, Nothofagus plicata, from southern and southwestern continental Australia is... more A new leaf species of Nothofagaceae, Nothofagus plicata, from southern and southwestern continental Australia is described. N. plicata has plicate vernation and is therefore considered to be a deciduous species. This provides the first macrofossil evidence for deciduous elements on mainland Australia in the Eocene, as well as the previously missing macrofossil evidence for Nothofagus forests which palynologists have suggested existed in this region at that time.
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Seen by:Some Permian glossopterid fructifications and leaves from the Bowen Basin, Queensland, Australia
Reference:
McLoughlin, S., 1990. Some Permian glossopterid fructifications and leaves from the Bowen Basin, Queensland, Australia. Review of Palaeobotany and Palynology 62, 11-40.
Three new glossopterid fructifications and a new Glossopteris leaf are described from Late Permian sediments of the... more Three new glossopterid fructifications and a new Glossopteris leaf are described from Late Permian sediments of the southwest and central Bowen Basin, Queensland, Australia. Glossopteris bucklandensis sp. nov. and the female fructification Ottokaria inglisensis sp. nov. are described from the Black Alley Shale, Denison Trough. Cometia biloba gen. et sp. nov. and Senotheca kingii sp. nov. are instituted for new female fructifications from the Burngrove and Fair Hill Formations respectively on the Comet Platform. A collection of female fructifications from the Rangal Coal Measures, Comet Platform, is assigned to Dictyopteridium walkornii (Rigby) comb. nov. Numerous specimens of O. inglisensis and D. walkomii show that receptacle dimension ratios and tubercle (ovule attachment point) densities are useful taxonomic features, whereas wing and stalk vs. receptacle dimension ratios are less consistent. Exceptionally high tubercle densities on some small fructifications possibly reflect limitation of receptacle growth induced by local ecological conditions.
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Seen by:Early Cretaceous (Neocomian) flora and fauna of the Lower Strzelecki Group, Gippsland Basin, Victoria
Reference:
McLoughlin, S., Tosolini, A.-M., Nagalingum, N.S. & Drinnan, A.N., 2002. The Early Cretaceous (Neocomian) flora and fauna of the lower Strzelecki Group, Gippsland Basin, Victoria, Australia. Memoirs of the Association of Australasian Palaeontologists 26, 1-144.
Fossil assemblages are described from the Tyers River Subgroup (late Berriasian to Hauterivian), Gippsland Basin,... more Fossil assemblages are described from the Tyers River Subgroup (late Berriasian to Hauterivian), Gippsland Basin, Victoria. The assemblages include plant macrofossils referable to 33 form-species including five new species (Isoetites abundans Tosolini & McLoughlin, Coniopteris victoriensis Nagalingum & McLoughlin, Otozamites douglasii Drinnan, Brachyphyllum tyersensis Tosolini & Nagalingum, Otwayia hermata Tosolini & McLoughlin) and three new combinations [Medwellia lacerata (Douglas) Nagalingum & McLoughlin, Rintoulia variabilis (Douglas) McLoughlin & Nagalingum, Pachydermophyllum austropapillosum (Douglas 1969) McLoughlin & Nagalingum]. Macrofossil assemblages include representatives of the Hepaticales, Isoetales, Equisetales, Filicopsida, seed-ferns, Coniferales and unionid bivalves. Co-preserved mesofossil suites include dispersed cuticle fragments, seed coats, seed megaspore membranes, microspore clusters, fern leptosporangia, charcoalified wood, resin blebs, epiphyllous fungal shields, clitellate annelid cocoons, insect exoskeleton fragments and coprolites. Sixteen lycophytic megaspore taxa were identified from the succession including six newly described species (Erlansonisporites confertus Tosolini, Favososporites brevis Tosolini, Hughesisporites australis Tosolini, Paxillitriletes rintoulensis Tosolini, Striatriletes imperfectus Tosolini, Trikonia locmaniensis Tosolini). These represent the first Neocomian megaspores formally described from Australia and their diversity and abundance indicates that lycophytes represented a significant component of the Early Cretaceous vegetation. The Tyers River Subgroup shares some taxa with the well-studied Koonwarra Fossil Bed (Aptian) flora of the Gippsland Basin but lacks several key elements (Ginkgoales, angiosperms and large-leafed araucarian conifers) and is more closely comparable to Jurassic floras of eastern Australia in its strong representation of bennettitalean, pentoxylalean and other seed-fern remains. The Tyers River Subgroup flora differs from coeval northwestern Australian floras by possession of smaller-leafed bennettites, Komlopteris and Pachydermophyllum species and by the lack of dipteridacean and gleicheniacean/lophosoriacean fern macrofossils. This intra-Australian provincialism is interpreted to be largely a function of palaeolatitude-induced climatic differences. Six major biofacies (one divisible into four sub-facies) are recognized in the Tyers River Subgroup and are attributable to three broad environmental settings within fluvial depositional tracts. Channel deposits host principally detrital plant remains derived from a broad range of riparian, upland, and reworked floodbasin communities. Silty floodbasin deposits typically host a mixture of pteridosperm-, fern- and lycophyte-dominated assemblages derived from a mosaic of herb-, shrub- and small tree-dominated communities developed mainly in perennially or seasonally wet environments. Better-drained, intervening levee, crevasse splay and neighbouring upland environments are interpreted to have hosted a conifer-dominated flora contributing to conifer-, root/rhizome-, megaspore-and clitellate-rich fossil associations. The floristic diversity, foliar morphology of selected species, strong representation of deciduous taxa and sedimentological data collectively suggest that seasonally cold conditions prevailed during the Neocomian-Aptian compared to the Albian in southeastern Australia.
An Early Jurassic flora from the Clarence-Moreton Basin, Australia
Reference:
Jansson, I.-M., McLoughlin, S., Vajda, V. & Pole M., 2008. An Early Jurassic flora from the Clarence-Moreton Basin, Australia. Review of Palaeobotany and Palynology 150: 5-21.
A low-diversity Early Jurassic flora preserved in floodbasin siltstones of the Marburg Subgroup at Inverleigh Quarry... more A low-diversity Early Jurassic flora preserved in floodbasin siltstones of the Marburg Subgroup at Inverleigh Quarry in the Clarence-Moreton Basin, eastern Australia, is dominated by Allocladus helgei Jansson sp. nov., a conifer with denticulate leaves tentatively attributed to Araucariaceae. The assemblage also includes Rintoulia variabilis and Caytoniales, (Caytonia cucullata McLoughlin sp. nov. and cf. Sagenopteris nilssoniana), reinforcing the wide distribution of this order in Early to Middle Jurassic floras of Gondwana. Ferns (Cladophlebis and Sphenopteris species) and isoetalean lycophytes (Isoetites sp.) constitute the herbaceous elements of the flora. The palynoflora is dominated by cheirolepidiacean (Classopollis) pollen and is attributable to the upper part of the Corollina (=Classopollis) torosa Zone of late Pliensbachian– early Toarcian age (180–185 Ma). The Inverleigh flora represents one of the few Australian assemblages dated between the major phases of floristic turnover at the end of the Triassic and the Toarcian. Sedimentological characteristics, cuticular features of the conifer leaves and the abundance of free-sporing plants indicate a relatively humid palaeoclimate for the Clarence-Moreton Basin Early Jurassic.
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