6,132 research outputs found
Macrofossils as indicators of Plio-Pleistocene climates in Tasmania and Antarctica
Plant macrofossils can be used as proxy palaeoclimatic indicators, since both the taxa present at a site and the form ofleaves depend on the climate, and macrofossils are rarely transported far. In the simple case of the Sirius Group Nothofagus leaves and wood in Antarctica, the fossils provide data on climate that suggest temperatures at the time of deposition were in the order of> 10°C warmer than at present. While the age of the fossils is still debated, the climatic signal is not. However, in more subtle cases, where the climatic differences are smaller and the fossil evidence is more complex, it is critical to interpret the evidence cauriously. Macrofossils from Pleistocene localities in Tasmania provide a clear signal on temperature and rainfall that is sometimes at odds with pollen-based reconstructions, bur the former is inherently likely to be more accurate
K-Ar dated palynofloras in Tasmania 1: Early Oligocene, Proteacidites tuberculatus Zone sediments, Wilmot Dam, northwestern Tasmania
Tertiaty lake sediments at Wilmot Dam, northwestern Tasmania, are dated as Lower Proteacidites tuberculatus Zone, based on the palynological zonation developed for the Gippsland Basin in eastern Bass Strait. The age limits of Early-Middle Oligocene for this zone are in excellent agreement with a K/Ar date of 26.7 Ma for basalts capping this deposit. Three new species are described: Tricolpites stylidioides, Mutisiapollis patersonii and Periporopollenites hexaporus. The first two appear to be the earliest records to date of Stylidiaceae and Mutisia
(Asteraceae:tribe Mutisieae) respectively
The macrofossil record of Proteaceae in Tasmania: a review with new species
About ten taxa of Proteaceae are known from the Early Eocene in Tasmania, one from a Late Eocene site, 22 from four Early Oligocene sites, one from a Late Oligocene/Early Miocene site, 12 or 13 from two Early Pleistocene sites, and five or six from the Middle and Late Pleistocene. Most of the Tertiary fossils are of extinct species, but the extant species Lomatia fraxinifolia and Telopea truncata have been recorded from the Early Oligocene as well as apparent close relatives of the subalpine rainforest species Orites milliganii, and the sub-tropical rainforest species, O. excelsa. None of the Early Oligocene species are known from more than one site, implying very high regional diversity, and floristic differentiation among the sites. High diversity of Proteaceae at some sites may be associated with oligotrophic soils. There is no evidence of any of the modern species-rich scleromorphic groups of Proteaceae except Banksiinae. Scleromorphy was well established in Oriteae, Embothrieae and Banksiinae by the Early Oligocene. The Early Eocene fossils have very small stomata, sparsely distributed on the leaf, which may have been due to elevated atmospheric CO2. All extant Tasmanian genera and many extant species were present by the Early Pleistocene as well as some extinct species. The specific diversity within the region was probably higher than it is now.
In order to resolve a nomenclatural problem with the genus Proteaciphyllum, Euproteaciphyllum G.J.Jord., R.J.Carp. & R.S.Hill, gen. nov. is proposed and this name is applied to 10 previously described species. The Tasmanian fossil taxa include three new records, and nine new species: Euproteaciphyllum brookerensis G.J.Jord., R.J.Carp. & R.S.Hill, sp. nov., and E. tasmanicum G.J.Jord., R.J.Carp. & R.S.Hill, sp. nov. from Early Eocene sediments; and Orites milliganoides G.J.Jord., R.J.Carp. & R.S.Hill, sp. nov., O. scleromorpha G.J.Jord., R.J.Carp. & R.S.Hill, sp. nov., E. papillosum G.J.Jord., R.J.Carp. & R.S.Hill, sp. nov., E. polymorphum G.J.Jord., R.J.Carp. & R.S.Hill, sp. nov., E. microlobium G.J.Jord., R.J.Carp. & R.S.Hill, sp. nov., E. falcatum G.J.Jord., R.J.Carp. & R.S.Hill, sp. nov., and E. serratum G.J.Jord., R.J.Carp. & R.S.Hill, sp. nov. from Early Oligocene sediments
Pinnule and stomatal size and stomatal density of living and fossil bowenia and eobowenia specimens give insight into physiology during cretaceous and eocene paleoclimates
Premise of research. This study compares the pinnule morphology of three fossil Bowenia species, one Eobowenia (fossil) species, and several Bowenia fossil pinnule fragments with the two extant Bowenia species. Methodology. Pinnule area, stomatal density, and size have been measured on fossil and extant specimens. Measures have been correlated with solar radiation and temperature to ascertain any correlations. Environment and climate variables have been chosen, as they have changed since the Eocene and Lower Cretaceous when the Australian and South American fossils were growing. Pivotal results. Two of the fossil Bowenia species and Eobowenia have significantly smaller pinnules than the living species, and all the fossils have relatively small and sparse stomata compared with the living species. Extant Bowenia pinnule area is positively correlated with daily radiation and temperature. Conclusions. Those fossil species with small pinnules likely lived in relatively dark environments where small pinnules aided the capture of sunflecks and/or facilitated light capture. The smaller and sparser stomata may have limited the potential sites for fungal invasion in the extremely humid growth conditions without hampering overall growth rates in the prevailing very high atmospheric CO 2 levels
Extensive past distributions for major gondwanic floral elements: macrofossil evidence
The past geographical positions and climates of the high latitude Southern Hemisphere land masses (New Zealand and the southern parts of South America and Australia) are crucial to an understanding of plant evolution and migration in the region.
A review of the macrofossil record reveals many examples of taxa which are present as fossils on one or two of these land masses but now occur elsewhere in the Southern Hemisphere. The main examples include Austrocedrus, Libocedrus (Cupressaceae), Araucaria sectionColumbea (Araucariaceae) and Nothofagus subgenera Nothofagus and Fuscaspora in Australia, Eucalyptus (Myrtaceae) and mn-Gymnostoma Casuarinaceae in New Zealand and probably South America, Araucaria section Intermedia in New Zealand and Akania (Akaniaceae) and Dacrycarpus (Podocarpaceae) in South America. The local extinction of these taxa is probably due to a variety of factors, including climatic change, microsite changes due to the northward movement of land masses, and changes in the frequency of catastrophic disturbance
New macrofossils of the Australian cycad bowenia and their significance in reconstructing the past morphological range of the genus
Premise of research:This study describes a new fossil species of Bowenia and reconsiders known fossil species and their evolutionary significance.Methodology:The fossils we describe here were collected for this study or were available from previous collections made over several decades. The fossils were identified by direct comparisons with extant and fossil species.Pivotal results:A reexamination of known and newly discovered Bowenia macrofossils confirms the presence of at least three fossil species in Australia. A new species, Bowenia johnsonii, is described from the southernmost location, the Early Eocene Lowana Road site in southwest Tasmania. When compared with the two extant species, the three fossil species demonstrate two distinct pinnule morphologies: relatively small with distinct serrations in Bowenia eocenica and Bowenia papillosa and larger pinnules with minute serrations in B. johnsonii. When considered together, the stomata of the extant species are denser and larger than those of the fossil taxa.Conclusions:The cycad genus Bowenia has a restricted extant distribution along the east coast of Queensland but is known more widely within Australia from fossils. The fossil record of Bowenia is important in documenting the past distribution of this genus, and aspects of its pinnule morphology provide insights into its environmental interactions. The possible relationship of the fossil Bowenia species with the Aptian Argentinian genus Eobowenia is considered, along with some fragmentary Australian fossils of probable Bowenia
Dramatizing an Articulation of the (P)Artistic Researcher’s Posthumanist Pathway to a ‘Slow Professorship’ Within the Corporate University Complex
Within academia, the practical arts researcher endures an unstable status owing, in part, to the diverse research methodologies gathered underneath the umbrellas of Practice-[led/based/as/for]- Research. (P)Artistic Research is difficult to define, no less validate, in a result-oriented, data-driven, ‘performance’-measuring culture. The (P)Artistic Researcher embodies dissent in such contexts, as the nature of most artistic research is process-oriented, collaborative and solution-finding. In response to Berg and Seeber’s pleas for ‘slowness’ in The Slow Professor, this chapter reflects critically on the author’s habits and history as a (P)Artistic Researcher while moving through a ‘gap’ in employment, from a dramatic resignation at one institution to an acceptance of a new post at another institution, one year later. This writing is contaminated by aspects of the author’s ‘playwrighting’ practice, becoming a posthuman ‘playper’ in which forms of writing are intertwined, and structure, layout and grammatical positioning are used innovatively to produce new knowledge which is not ‘in-prism-ed’ by the narrow perspective of the corporate university. The content of the ‘playper’ offers a malleable frame with several pedagogical points of entry, including prompts, provocations and practical exercises which intend to slowly contaminate the classroom with a conscientious commitment to a posthuman understanding of the world
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