Studies in New Zealand Oligocene and Miocene Plant Macrofossils

<p>Assemblages of fossil leaves ranging in age from Upper Oligocene to Upper Miocene or Lower Pliocene have been examined from localities in Southland, Central Otago, the Dunedin area, the Buller region and Great Barrier Island. Nearly 200 form taxa have been recognized so far; of these 52 are figured and described and the remainder are included in an illustrated catalogue. Conifers, Casuarinaceae and Nothofagus spp. are discussed in detail. Thirteen new species are named and described: Gleichenia southlandica, Hypolepis maruiensis, Blechnum maruiense, Dacrydium (Lagarostrobos) franklinoides, Microcachrys imbricata, Phyllocladus strictus, Libocedrus compressa, Nothofagus southlandica, Gymnostoma stellata, Gymnostoma crassa, Casuarina avenacea, Metrosideros diffusoides and ? Eucalyptus roxburghiensis. Six new species are described but not named as more detailed study is still proceeding. A further ten new form taxa are identified to genus level only. The fossil flora from the Kaikorai Valley, Dunedin, originally described by Oliver (1936) is revised and Blechnum proceroides, Nothofagus pinnata, N. australis, N. kaikoraiensis and Ripogonum latipetiolatum are new names arising from this revision. The fossil assemblages from Southland and Central Otago are derived from heath, swamp and forest communities developed on an early to mid Tertiary peneplain. In contrast the fossil floras of the Buller region reflect predominantly forest vegetation developed on young soils of a prograding coastal floodplain backed by rapidly rising fault block ranges, while the fossil floras of Dunedin and Great Barrier Island reflect vegetation periodically affected by volcanic activity. Late Oligocene and Miocene climates throughout New Zealand appear to have been humid and at least as warn as Auckland today, although conditions on the east coast of the South Island may have been cooler and drier than on the west. The sediment containing the Landslip Hill fossil flora is interpreted as a silcrete and resembles similar deposits in Australia. The uncompressed state of the fossils and the preservation of turgid cell structures indicates early silica cementation in a surface or near-surface environment, probably as a result of direct precipitation of silica from ground water. The present-day New Zealand flora appears to be derived in part from the late Cretaceous flora of coastal eastern Gondwanaland. Other south-west Pacific floras may stare a similar origin, and may also have contributed to the New Zealand flora following fragmentation of the continental margin. The distribution of New Zealand Tertiary plants, as far as it is known, is consistent with my inferred paleogeography.</p>

Studies in New Zealand Oligocene and Miocene Plant Macrofossils

<p>Assemblages of fossil leaves ranging in age from Upper Oligocene to Upper Miocene or Lower Pliocene have been examined from localities in Southland, Central Otago, the Dunedin area, the Buller region and Great Barrier Island. Nearly 200 form taxa have been recognized so far; of these 52 are figured and described and the remainder are included in an illustrated catalogue. Conifers, Casuarinaceae and Nothofagus spp. are discussed in detail. Thirteen new species are named and described: Gleichenia southlandica, Hypolepis maruiensis, Blechnum maruiense, Dacrydium (Lagarostrobos) franklinoides, Microcachrys imbricata, Phyllocladus strictus, Libocedrus compressa, Nothofagus southlandica, Gymnostoma stellata, Gymnostoma crassa, Casuarina avenacea, Metrosideros diffusoides and ? Eucalyptus roxburghiensis. Six new species are described but not named as more detailed study is still proceeding. A further ten new form taxa are identified to genus level only. The fossil flora from the Kaikorai Valley, Dunedin, originally described by Oliver (1936) is revised and Blechnum proceroides, Nothofagus pinnata, N. australis, N. kaikoraiensis and Ripogonum latipetiolatum are new names arising from this revision. The fossil assemblages from Southland and Central Otago are derived from heath, swamp and forest communities developed on an early to mid Tertiary peneplain. In contrast the fossil floras of the Buller region reflect predominantly forest vegetation developed on young soils of a prograding coastal floodplain backed by rapidly rising fault block ranges, while the fossil floras of Dunedin and Great Barrier Island reflect vegetation periodically affected by volcanic activity. Late Oligocene and Miocene climates throughout New Zealand appear to have been humid and at least as warn as Auckland today, although conditions on the east coast of the South Island may have been cooler and drier than on the west. The sediment containing the Landslip Hill fossil flora is interpreted as a silcrete and resembles similar deposits in Australia. The uncompressed state of the fossils and the preservation of turgid cell structures indicates early silica cementation in a surface or near-surface environment, probably as a result of direct precipitation of silica from ground water. The present-day New Zealand flora appears to be derived in part from the late Cretaceous flora of coastal eastern Gondwanaland. Other south-west Pacific floras may stare a similar origin, and may also have contributed to the New Zealand flora following fragmentation of the continental margin. The distribution of New Zealand Tertiary plants, as far as it is known, is consistent with my inferred paleogeography.</p>

ON THE CHAUN PALAEOFLORA FROM NON-MARINE CRERACEOUS OF CHUKOTKA

The Cretaceous fossil floras from the formations of the Okhotsk-Chukotka volcanogenic belt differ significantly by its systematic composition from the same-age fossil floras from the coastal lowland sedimentations. The peculiarities of fossil floras from the volcanogenic disposals are the most obvious in Chaun Flora firstly found in the volcanogenic formations of Pegtymelski Arch in Central Chukotka. L.B. Golovneva presented the results of the long-term study of this flora in the monograph published in 2018. On the base of these data and using our own experience in the stratigraphy of the Okhotsk-Chukotka volcanogenic belt and the study of the vegetation cover dynamics in the areas of modern volcanism of Kamchatka we showed that most likely Chaun Flora formed on juvenile substrata in the central parts of the vast volcanic fields being isolated form the sources of diasporas. The Chaun Flora has not clear affinity in neither lateral nor stratigraphic localization, because the fossil remains of characteristic plant species occur in different-age formations on all extent of the volcanogenic belt. The species characteristic for Chaun Flora are indicators of the certain environmental conditions and reflect the peculiarities of the processes of fossilization in the areas of terrestrial volcanism from Turon until Campanian inclusive.

Palaeocarpological and palaeoclimatic studies of the murtic interglacial flora of the Belarusian upland

The Muravian interglacial horizon is the last warm period of time span closest to our time, as well as one of the marking horizons in the complex composed layer of Quaternary deposits in Belarus. The study of the Muravian deposits, as well as an elucidation of the paleogeographic conditions that existed at that time, can make it possible to predict climate changes on our planet in the future. Based on the analysis of palaeocarpological materials obtained by the author in the study of reference sections located within the territory of the Belarusian upland and reflecting the optimal phases of the Muravian interglacial, a brief analysis of the composition of fossil floras is carried out, the conditions for their formation are established, and paleoclimatic reconstructions were performed on the basis of the obtained materials. The data obtained indicate that the average July temperatures at the optimum of the Muravian interglacial on the territory of the Belarusian upland were +17.0 till +24.0 °С for the eastern regions and +17.0 till +21.2 °С for the Grodno upland. The average January temperature ranged from +2.0...+7.0 to –3.0...–7.2 ºC. The results obtained are in good agreement with the data of other methods, in particular, palynological analysis based on the study of fossil pollen and spores. In accordance with the modern climatic indicators of the territory of Belarus, the climate at the optimum of the Muravian interglacial was at least several degrees warmer than the current one, and the winters were much milder.

Sampling fossil floras for the study of insect herbivory: how many leaves is enough?

Despite the great importance of plant–insect interactions to the functioning of terrestrial ecosystems, many temporal gaps exist in our knowledge of insect herbivory in deep time. Subsampling of fossil leaves, and subsequent extrapolation of results to the entire flora from which they came, is practiced inconsistently and according to inconsistent, often arbitrary criteria. Here we compare herbivory data from three exhaustively sampled fossil floras to establish guidelines for subsampling in future studies. The impact of various subsampling routines is evaluated for three of the most common metrics of insect herbivory: damage type diversity, nonmetric multidimensional scaling, and the herbivory index. The findings presented here suggest that a minimum fragment size threshold of 1 cm2 always yields accurate results and that a higher threshold of 2 cm2 should yield accurate results for plant hosts that are not polyphyletic form taxa. Due to the structural variability of the plant hosts examined here, no other a priori subsampling strategy yields consistently accurate results. The best approach may be a sequential sampling routine in which sampling continues until the 100 most recently sampled leaves have caused no change to the mean value or confidence interval for damage type diversity and have caused minimal or no change to the herbivory index. For nonmetric multidimensional scaling, at least 1000 cm2 of leaf surface area should be examined and prediction intervals should be generated to verify the relative positions of all points. Future studies should evaluate the impact of subsampling routines on floras that are collected based on different criteria, such as angiosperm floras for which the only specimens collected are those that are at least 50 % complete.

The problem of the non-marine cretaceous strata correlation in the north-east of Russia: the conditions of florogenesis in the volcanic region

The most part of the fossil floras from the Cretaceous volcanogenic formations of the North-East of Russia differs significantly in systematic composition from the same-age paleofloras of coastal lowlands. In order to explain the features of their formation, the modern data on the dynamics of vegetation cover on the volcanic plateaus of Central Kamchatka were used. It was shown that in the sites where the paleofloras in geological disposals of the Okhotsk-Chukchi volcanogenic belt were found, there was practically no erosion, but there was the abundance of volcanic material suitable for the formation of disposals. After the massive powerful eruptions, the inland districts of the vast volcanic areas were isolated from the sources of diasporas. Vegetation cover in these areas recovered mainly due to the pool of local species, i.e., maintained as a diasporic sub-climax. The lack of competition from angiosperms contributed to the long-term preservation in such paleofloras the ancient groups of plants and the formation of new taxa on their basis.

Palaeoflora of Kamenica (Pranjani basin, western Serbia)

Palaeofloras of the Paleogene in Serbia are relatively rare, especially in comparison with floras from Neogene sediments. Most Paleogene phytoassociations from the territory of Serbia existed in a dry and warm climate. The youngest Paleogene phytoassociation originates from the Pranjani Basin (Western Serbia), locality Kamenica. The age of this palaeoflora is determined as Late Oligocene. This fossil plant assemblage is different from other Paleogene phytoassociations. The palaeoflora from Kamenica is characterized with leaf imprints larger than in other Paleogene fossil floras. Furthermore, it differs in taxonomical composition. The prevailing forms are conifers and representatives of broad-leaved evergreen forests. In other Paleogene phytoassociations, elements of broad-leaved evergreen forests are extremely rare. The dominating elements in the palaeoflora of Kamenica are the conifers, especially Glyptostrobus, Pinus, Sequoia and Tetraclinis. The representatives of the broad-leaved evergreen forests are Laurus, Magnolia, ?Quercus?, etc.