Climate Leaf Analysis Multivariate Program Research Articles

Monsoon influence on plant diversity in northern Indochina: Evidence from the late Miocene Yen Bai flora, northern Vietnam

Indochina, as a global biodiversity hotspot, offers the potential for understanding the evolution of biodiversity. However, the historical narrative of plant diversity in this region remains enigmatic due to limited fossil records. Here, we report a newly discovered megafossil flora from the late Miocene of the Yen Bai Basin, northern Vietnam. This megafossil flora suggests that the late Miocene vegetation in northern Vietnam comprised mixed tropical evergreen and deciduous broadleaved forest components mainly characterized by Fabaceae, Fagaceae, and Lauraceae bearing strong resemblance to the modern vegetation in northern Vietnam. Paleoclimate reconstruction for this plant fossil assemblage using the Coexistence Approach indicates a mean annual temperature (MAT) of 18.5–23.0 °C and a mean annual precipitation (MAP) of 1183.1–2078.5 mm. Similarly, employing the Climate-Leaf Analysis Multivariate Program yields an MAT of 21.3 ± 2.3 °C and a growing season precipitation (GSP) of 1328.6 ± 606.0 mm. The length of the growing season was about eleven months. Overall these results indicate a modern-like warm and humid tropical monsoon climate in northern Vietnam during the late Miocene. Climatic comparison of the Yen Bai with other fossil floras in northern Vietnam and southern China reveals the relative stability of temperature seasonality since the middle Eocene but obvious long-term variation in precipitation seasonality, particularly in respect of precipitation during the three consecutive driest months (X3.DRY). This suggests the Asian monsoon in northern Vietnam underwent important changes from the middle Eocene to the late Miocene, and intensified significantly during the middle and late Miocene. Our results show the modernization of plant diversity in northern Indochina had its origin in the Paleogene and further developed in the late Miocene, and was linked to the evolution of the Asian monsoon mainly in terms of changes in dry season precipitation.

The early Paleocene (Danian) climate of Svalbard based on palaeobotanical data

AbstractThe early Paleocene (Danian) Barentsburg flora from the Firkanten Formation, Svalbard, provides a valuable insight into the environment and climate of the Arctic early in the warm Palaeogene prior to the Paleocene–Eocene Thermal Maximum (PETM) event. The flora includes c. 50 species of ferns, ginkgos, conifers and angiosperms. Angiosperms predominate and are represented by the families Platanaceae, Cercidiphyllaceae, Trochodendraceae, Hamamelidaceae, Fagaceae, Betulaceae, Nyssaceae and several taxa of uncertain taxonomic position. Palaeoclimate parameters, calculated using a new calibration of the Climate Leaf Analysis Multivariate Program (CLAMP), indicate that Svalbard in the early Paleocene was characterized by a temperate, maritime, humid, seasonal climate with cool mild winters and warm summers. Humidity was highest during winter months. Short‐term winter snow cover and light frosts were likely to have been frequent. The CLAMP analysis yields a mean annual temperature of 10.1 ± 1.98°С, a warmest month mean temperature of 19.2 ± 2.49°C and a coldest month mean temperature of 1.7 ± 3.24°С. The growing season lasted c. 6 months. Precipitation during this growth period was 572.4 ± 296.50 mm, while vapour pressure deficit and potential evapotranspiration indicate very high humidity year‐round, with summer being only slightly drier than winter. Taken together with data from other early Paleocene circum‐Arctic sites, these results point to highly uniform, temperate and extremely humid conditions around the margins of the early Cenozoic Arctic Ocean. This condition represents the warm background condition that dominated in the Arctic prior to the anomalous extreme warmth of the early Eocene.

Latest Neogene Paleoclimate Variation in Yunnan, Southwest China, Revealed by Fossil Leaf Physiognomy

AbstractYunnan Province, located in the southeastern margin of the Tibetan Plateau, can provide important information on how climate change was influenced by global cooling. However, its variation patterns in temperature and precipitation during the latest Neogene are not well‐understood. Based on the 357 specimens assigned to 31 morphotypes of plant fossils from the upper Pliocene Ciying Formation in Yiliang County, Yunnan Province, Southwest China, paleoclimate was estimated by Leaf Margin Analysis and Climate Leaf Analysis Multivariate Program. Compared to the present climate, the mean annual temperature and coldest month temperature have not changed significantly since the late Pliocene, whereas the warmest month temperature has decreased significantly. All precipitation‐related parameters have decreased, particularly winter precipitation. Combined with the climatic data of the same period in other areas of Yunnan, the western and eastern Yunnan has shown a similar pattern in temperature variation since the late Pliocene except for central Yunnan; whereas the variation in precipitation does not follow a common law except for a consistent decrease in winter precipitation. Our study reinforced the fact that under the background of global cooling and intensified monsoon systems, different areas of Yunnan exhibit different climatic responses to these changes because of their topographic heterogeneities.

Quantitative Reconstruction of Paleoclimatic Changes in the Late Miocene Eastern Zhejiang Based on Plant Fossils

With a series of Cenozoic climate fluctuations, the global paleoclimate shifted from a warm climate to a cold climate, causing Arctic ice caps to be formed. The Late Miocene is a critical time in this transition period, in which the climate was rapidly cooling. Plant fossils from this epoch could be used as ideal indicators for reconstructing climate change throughout this time interval. In this study, plant fossils were collected from the Shengxian Formation in Ninghai and Tiantai of eastern Zhejiang. We divided the fossiliferous strata of the Shengxian Formation into five layers according to different lithology and chronological order, which were named: JHU0, DLX, JHU1, JHUW, and JHU3 from old to new geological times, respectively. We used Leaf Margin Analysis and Climate Leaf Analysis Multivariate Program to reconstruct paleoclimatic changes in eastern Zhejiang during the Late Miocene. The paleoclimatic information of the five stages from old to new times was obtained based on the plant fossils of each layer. The mean annual temperature values in eastern Zhejiang were reconstructed using the Climate Leaf Analysis Multivariate Program and Leaf Margin Analysis at the same time. However, the former mean annual temperature values are lower than the latter values. After comparing the two sets of mean annual temperature data with previously reported values, it is found that the results obtained by Climate Leaf Analysis Multivariate Program are more reliable, whose values are 18.05 °C, 16.03 °C, 17.96 °C, 16.57 °C, and 15.52 °C from old to new times, respectively. Moreover, 11 climatic parameters were reconstructed using the Climate Leaf Analysis Multivariate Program PhysgAsia2 calibration, among which the growing season precipitation was found to be 195.54 cm, 181.25 cm, 207.99 cm, 180.7 cm, and 165.07 cm; while the difference between the coldest and warmest months was found to be 22.14 °C, 23.4 °C, 22.07 °C, 21.36 °C, and 23.37 °C. The relatively low difference between the coldest and warmest months values and the growing season precipitation values during the Late Miocene might be due to a weaker East Asian monsoon system in the Late Miocene than in modern times.

Plant Megafossils, Palynomorphs, and Paleoenvironment from the Late Middle to Late Eocene Burnaby Mountain Flora, Huntingdon Formation, British Columbia, Canada

Premise of research. The Eocene fossil flora of the area around Vancouver, British Columbia, is poorly known despite work beginning in the 1890s to 1920s. The floristic character of the previously unstudied Burnaby Mountain flora from the Huntingdon Formation in British Columbia is reconstructed using plant megafossils and palynology. This site offers insight into the terrestrial vegetation and paleoclimate during the late middle to late Eocene of the Pacific Northwest of North America in a coastal setting during a global cooling trend.Methodology. Megaflora and microflora were identified, and the combined flora was compared with that of coeval floras from northwestern Washington. Paleoclimate was reconstructed from leaf morphology using the Climate Leaf Analysis Multivariate Program, leaf margin analysis, and leaf area analysis. A probabilistic nearest-living-relative approach was used to reconstruct paleoclimate independently of leaf morphology, using taxonomic identifications from both mega- and microfossils. These data were combined in an ensemble approach.Pivotal results. The Burnaby Mountain fossil flora is late middle Eocene to late Eocene in age and shares key plant taxa with the coeval Upper Ravenian flora of the Puget Group and the upper Chumstick Formation of northwestern Washington. The fossil flora contained a mix of subtropical and temperate forest elements, including rare palm and possible cycad leaf fragments, rare conifer pollen, and a diversity of broad-leaved trees.Conclusions. The reconstructed paleoclimate suggests humid warm-temperate to marginally subtropical conditions in coastal British Columbia during the late middle Eocene to late Eocene. An ensemble paleoclimate approach provided a most parsimonious mean annual temperature estimate of 16.2°C±3.1°C for the Burnaby Mountain fossils and mean annual precipitation of 134±56 cm. A modern climatic analog is present on the East Coast of the United States in North Carolina, where palms are part of the native flora.

First fossil record of Pelekium (Thuidiaceae) from the middle Miocene Zhangpu amber in Asia

ABSTRACT Zhangpu amber is an important source of Miocene bryophytes in China. Zhangpu amber originates from the Middle Miocene Climatic Optimum (MMCO), which is well known for the appearance of Dipterocarpaceae-dominated megathermal forests in East Asia. The humid and warm climate of these forests might have triggered the development of diverse epiphytic bryophytes; however, the Middle Miocene fossils of bryophytes are rare in Asia. Here, we present evidence for Pelekium (Thuidiaceae) in Zhangpu amber. The fossil is characterised by: (i) regularly pinnate ramifications; (ii) deltoid leaves with a single and percurrent Costa; (ⅲ) abundant unbranched and uniseriate paraphyllia covering the stems and branches; (ⅳ) differentiated stem and branch leaves. It represents the first fossil record of Pelekium, showing that the genus already existed in Fujian, South China during the Middle Miocene. Our fossil enriches the Neogene fossil record of bryophytes in East Asia. Extant Pelekium species comprises stenoecious plants that are mainly distributed in tropical areas, often grow on bark in humid forests. The occurrence of fossil Pelekium from Zhangpu amber is in good accordance with the palaeoclimatic reconstruction based on the Climate Leaf Analysis Multivariate Program.

A novel fossil-species of Meliolinites Selkirk (fossil Meliolaceae) and its life cycle stages associated with an angiosperm fossil leaf from the Siwalik (Mio-Pliocene) of Bhutan sub-Himalaya

Here, we report the in-situ occurrence of a new fossil-species of Meliolinites (fossil Meliolaceae), Meliolinites bhutanensis sp. nov. on the cuticle fragments of a compressed angiosperm dicot leaf recovered from the middle Siwalik (Formation II: latest Miocene to Pliocene) of Bhutan, eastern Himalaya. This unique foliicolous new fossil fungal species features well-preserved mycelia consisting of superficial, brown to dark brown, septate, thick-walled, branching hyphae with bi-cellular appressoria, unicellular phialides, and a characteristic long, slightly curved hyphal seta. The web-like, brown to dark brown fungal colonies also include globose to sub-globose, dark brown ascomata, and oblong to broadly cylindrical, 5-celled, 4-septate, brown to dark brown, mature ascospores. As almost all features of different stages in the life cycle (ascospores, mature germinating ascospores, superficial lateral hyphae, hyphal seta, hyphopodia, mycelial colony, and ascomata) of this new fossil-species are found, we have proposed the first time a possible life cycle of fossil-species of Meliolaceae. The in-situ evidence of M. bhutanensis on the host leaf cuticle indicates the possible existence of a host-ectoparasite relationship in Bhutan sub-Himalaya's ancient warm and humid tropical evergreen forest during the deposition. So, M. bhutanensis might have thrived generally under warm and humid climate conditions for its growth and development in the Mio-Pliocene time, which is in conformity with our recently published quantitative climatic data by CLAMP (Climate Leaf Analysis Multivariate Program) analysis.

Long-term floristic and climatic stability of northern Indochina: Evidence from the Oligocene Ha Long flora, Vietnam

The antiquity of the tropical Asian flora is being revealed by recent detailed work on a number of Cenozoic plant megafossil sites, some of which have been radiometrically dated for the first time, but our knowledge of how the highly diverse modern biota came into being remains poor due to a sparsity of records. In this paper, we describe fossil plant assemblages from the Oligocene Dong Ho Formation of the Ha Long region, northern Vietnam. The Oligocene Ha Long megafossil flora has so far yielded 38 species, including conifers and angiosperms mainly belonging to Fagaceae, Lauraceae and Dipterocarpaceae, all with significant tropical Asian kinship. The Ha Long flora is similar to other Paleogene floras from southern China, especially those from the Pan Gulf of Tonkin region. The Ha Long floral composition is typical of a tropical-subtropical ecotone and the vegetation is reconstructed as a lowland tropical evergreen forest mixed with calcicole (limestone-loving) taxa. These taxa and the vegetation type they comprise still exist in this area. Palaeoclimate reconstruction made using both the Coexistence Approach and the Climate Leaf Analysis Multivariate Program indicate a mean annual temperature of ~20 °C, a coldest month mean temperature around 10 °C, and yearly precipitation averaging almost 2000 mm. These results suggest a warm and humid peripheral tropical environment. Floristic and climatic comparison within the Ha Long and other southern China palaeofloras reveals a long-term environmental, floristic and vegetational stability in this region since the Paleogene. This long-maintained plant diversity also provided a source for populating the East Asian flora and vegetation after the late Paleogene East Asian arid belt retreat.

Flora, vegetation and climate assessment of the Early/Middle Miocene Parschlug flora indicates a distinctly seasonal climate

The late Early/early Middle Miocene flora from Parschlug (Styria, Austria) is famous for its numerous specimens and high diversity. Some taxa previously described are revised here and 42 new angiosperm leaf morphotypes/taxa are described. The Climate Leaf Analysis Multivariate Program (CLAMP) is applied to assess the palaeoclimate. An update of the tool to assess the most suitable modern climate CLAMP calibration dataset is introduced. The Integrated Plant Record (IPR) vegetation analysis, assessing the most likely major vegetation type represented by a fossil flora, and similarity approaches Drudges 1 and 2, indicating the most similar modern vegetation proxies, had been previously applied to data from Parschlug. Both are again applied here on the enlarged floristic spectrum. The results indicate “sclerophyllous subhumid forest” as the most likely major zonal vegetation type for Parschlug and European vegetation, namely “Thermophilous mixed deciduous broadleaved forests”, distributed today in southern and southeastern Europe, as the most similar modern vegetation. The climate for Parschlug, inferred from CLAMP and the climate in the region of the modern vegetation proxies, indicates distinct seasonality in precipitation and temperature.

Catalogue of revised and new plant macrofossils from the Aquitanian-Burdigalian of Soma (W Turkey) – Biogeographic and palaeoclimatic implications

The position of Turkey between Europe and Asia makes this region interesting for palaeobotanical investigations. We investigated plant macrofossils from early Miocene deposits of W Turkey (Soma, Manisa) and compiled a catalogue of revised and new plant taxa. We documented 100 fossil-taxa, of which several are new for Turkey (Mahonia aff. pseudosimplex, Ziziphus paradisiaca, Comptonia longirostris, Carya denticulata, Viscum, Fatsia, Pungiphyllum cruciatum). Some previous records are rejected (e.g. Apocynophyllum, Cassia, Castanea, Ficus, Illicium, Liriodendron, Vaccinium). Using modern ecology and taphonomy, we reconstructed palaeoenvironments. We found evidence for a belt of drier, more open habitats with cycads, Dracaena, Mahonia, Smilax miohavanensis, and others. Other vegetation units comprise swamp and riparian forest with few dominants (expressed in high abundance of leaf specimens). On well-drained soils, lowland forest with large-leaved Lauraceae vel Fagaceae and rare elements (Fatsia) was present, while humid temperate broadleaf-deciduous and conifer forest flourished higher up. To infer palaeoclimate we used the Climate Leaf Analysis Multivariate Program (CLAMP) and compared the results with other Miocene localities of Turkey. Early Miocene floras had warm climates (mean annual temperature, MAT, and coldest month temperature, CMMT) with weak precipitation seasonality. MAT and CMMT were cooler during the early middle Miocene. Several fossil-taxa at Soma have biogeographic links with older/coeval localities in C Europe and/or the W Mediterranean region (cycads, Torreya, Dracaena, Smilax miohavanensis, Mahonia aff. pseudosimplex, Carya denticulata, Ilex miodipyrena, Pungiphyllum). Few taxa have clear links to C Asian floras (Comptonia longirostris). True E Mediterranean endemics are even rarer (Mahonia spp., Quercus sosnowskyi).

A mid-altitude area in southwestern China experienced a humid subtropical climate with subtle monsoon signatures during the early Oligocene: Evidence from the Ningming flora of Guangxi

The Oligocene marked the beginning of the present ‘icehouse’ epoch and witnessed the development and evolution of the Asian monsoon system (AMS). In this paper, the early Oligocene Ningming flora of Guangxi, southern China, is analysed to investigate the AMS based on climate proxies derived from Climate Leaf Analysis Multivariate Program (CLAMP). CLAMP results suggest that the prevailing climate experienced by the Ningming flora was humid subtropical with hot summers and warm winters. Although the record of precipitation seasonality is muted, it is about half as strong as that seen today in monsoon climates of South China, indicating a very weak monsoonal signal. Despite suggesting weak rainfall seasonality, the position of the Ningming flora in physiognomic space indicates that leaves exhibit monsoon-adapted morphologies, comparable to today's vegetation exposed to the Indonesia–Australia monsoon (I-AM) and the transitional monsoon area (influenced by the East Asia monsoon, South Asia monsoon and I-AM). Leaf architectural signatures reveal that the Ningming flora grew under a humid subtropical climate with subtle monsoon signatures. Although it is difficult to distinguish the different domains of the Asian monsoon under such a subtle monsoon influence, based on leaf signatures from southern Asia, it can be inferred that the Ningming Basin during the early Oligocene was exposed to a climate regime similar to that today influenced by the I-AM. In addition, the moist enthalpy method was applied to quantitatively reconstruct the paleoelevation of the Ningming Basin. This approach suggests a paleoelevation estimate of ~1.24–1.35 ± 0.52 km for the early Oligocene, suggesting that a drop in paleoelevation of the Ningming Basin took place after the early Oligocene (Rupelian). The CLAMP results suggest that the early Oligocene Ningming area was at a mid-altitude and experienced a humid subtropical climate with subtle monsoon signatures.

Evaluating the sensitivity of paleoclimate results using different approaches of leaf morphotype resolution: A case study using the Eocene Florissant paleoflora, central Colorado

We tested the sensitivity of paleoclimate estimates to different resolutions of leaf morphotype distinction by grouping one paleofloral collection three ways and comparing the results. We examined the different morphotype resolutions using a recently collected Eocene (34 Ma) fossil leaf assemblage from Florissant Fossil Beds National Monument Collection Site 9 (CS-9, Florissant, Colorado), an exposure that yields one of the most diverse sets of dicotyledonous angiosperm (‘dicot’) morphotypes yet analyzed from a single site within this well-studied formation. We grouped this collection using what are herein referred to as ‘Splitter’ (number of morphotypes n = 129), ‘Intermediate’ (n = 96), and ‘Lumper’ (n = 53) morphotyping approaches, which differed in their degree of delineating foliar morphotypes. Leaf Margin Analysis (LMA) and Leaf Area Analysis (LAA) were used to obtain paleotemperature and paleoprecipitation estimates from the morphotype datasets and Climate Leaf Analysis Multivariate Program (CLAMP) was employed to examine further parameters. We perform an additional paleoclimatic analysis of CS-9 in which we divide the site into three stratigraphic sections, and finally we perform an analysis on sample collections above and below a volcanic event horizon within CS-9. Whole collection results across the three morphotype resolutions indicate a mean annual temperature between 10.8 and 12.5 °C, and annual precipitation between 61.8 and 130.7 cm at the time of deposition. The ‘Splitter,’ ‘Intermediate,’ and ‘Lumper’ approaches provide very similar estimates by all methods of analysis and suggest that morphotype resolution specificity has very little effect on climatic results using these leaf physiognomic techniques.

Late Cretaceous–Paleogene Indian monsoon climate vis-à-vis movement of the Indian plate, and the birth of the South Asian Monsoon

After India separated from Gondwana, its 9000 km northward voyage from the Southern Hemisphere to its modern position joined with Eurasia took 160 million years. During that journey, India experienced a range of climatic conditions due to secular climate variations and its changing latitudinal position. Documenting India's climate during its trans-equatorial journey allows us to sample climate across the low latitudes, at a time when global temperatures were exceptionally high, such as we might experience in the future. Here, we reconstruct, quantitatively, the palaeoclimate of India during its voyage, focussing on the latest Maastrichtian–earliest Danian, late Paleocene, early Eocene and late Oligocene timeslices. We exploit the relationship between fossil leaf form and climate and use the Climate-Leaf Analysis Multivariate Program to reconstruct 24 individual palaeoclimate parameters, while fossil leaf traits also allow us to identify different monsoon types. We find that throughout the Paleogene India persistently experienced a monsoon climate similar to that of modern Indonesia-Australia; a monsoon system that exists today primarily as a function of seasonal trans-equatorial migrations of the Inter-tropical Convergence Zone (ITCZ). The reconstructed near-equatorial thermal regime of India was cooler, and showed a greater seasonal temperature variation than at similar latitudes today, suggesting a wider seasonal latitudinal migration of the ITCZ throughout the Paleogene. Leaf traits showing adaptation to the South Asia Monsoon only developed after the end of the Paleogene.

Three (middle to) late Miocene plant macroremain assemblages (Pitsidia, Kassanoi and Metochia) from the Messara–Gavdos region, southern Crete

Based on macroremains, we describe three fossil plant assemblages from the Miocene of the Messara Basin (southern Crete) and the adjacent Gavdos Island. The palaeoflora of Kassanoi, which is the oldest (Messara Basin, Viannos Fm, Serravallian/early Tortonian), is documented mainly by leaf imprints, including a fern, a conifer (Tetraclinis cf. salicornioides) and 23 angiosperms. The assemblage is dominated by Daphnogene polymorpha, Podocarpium podocarpum and Myrica lignitum. The plant record from Pitsidia (Messara Basin, Ambelouzos Fm, early Tortonian) comprises thousands of specimens. The plant fossils are preserved as imprints often covered by an inorganic encrustation (replica). One alga, 2 ferns, at least 5 conifers and more than 45 woody angiosperms were identified. Dominant taxa are Myrica and Pinus pitsidiensis, documented by numerous vegetative and reproductive organs (Zidianakis et al., 2015, 2016). Leaves of oaks (Q. pseudocastanea, Q. kubinyii) and Daphogene polymorpha as well as twigs of Taxodium dubium are also fairly common. From the palaeoflora of Metochia, which is the youngest (Gavdos Island, Metochia Fm, middle Tortonian), (Mantzouka et al., 2015), we report further taxa, including Quercus mediterranea, Ziziphus paradisiaca and a palm (Sabalites sp.). The vegetation is assessed both empirically (phytosociologically) and by Integrated Plant Record (IPR) Vegetation Analysis. The reconstructed vegetation models are presented in detail and discussed in the context of the geological and palaeontological settings of the area. The climate is assessed based on the Coexistence Approach (CA) and the Climate Leaf Analysis Multivariate Program (CLAMP). The palaeoclimatic datasets reveal a warm temperate to subtropical climate, probably with a weak seasonal drought.

CLAMP-based palaeoclimatic analysis of the late Miocene (Tortonian) flora from La Cerdanya Basin of Catalonia, Spain, and an estimation of the palaeoaltitude of the eastern Pyrenees

We analyse the late Miocene (early Tortonian) climate of the La Cerdanya Basin (Catalonia, Spain) using the Climate Leaf Analysis Multivariate Program (CLAMP) based on an assemblage comprising twenty-nine dicot leaf taxa. Results show a mean annual temperature of 11.4 ± 2.1 °C. The coldest mean monthly temperature was 1.8 ± 3.4 °C while the warmest was 21.6 ± 2.5 °C. Growing season was 6.8 ± 1.1 months in duration. Precipitation during this period was 1082 ± 317 mm, reaching 661 ± 38 mm in the three wettest consecutive months, while in the three driest months it was 194 ± 229 mm. These results indicate a permanently humid temperate climate, with warm and wet summers. Compared with published palaeoclimatic results obtained using the Coexistence Approach method, our CLAMP analysis indicates lower temperatures and higher rainfall during the driest month. The climatic parameters are consistent with the occurrence of a temperate mixed evergreen and broadleaf deciduous fossil assemblage in the late Miocene of the La Cerdanya Basin. The assemblage contains more taxa in common with coeval localities from northern and central Europe than with Mediterranean sites; its closest modern analogue is with the montane flora from Honshu Island (Japan). Palaeoaltitudinal estimation using the terrestrial lapse rate method suggests that the La Cerdanya Basin was positioned at 1100–1550 m during early Tortonian times. These results challenge previous palynological and isotopic studies that inferred a palaeoaltitude of c. 600 m in early Tortonian-Messinian times.

Leaf physiognomy records the Miocene intensification of the South Asia Monsoon

Abstract Our understanding regarding the onset and development of the modern South Asia monsoon (SAM) is still incomplete due to its complex nature and differing views about its relationship with major orographic features such as the Himalaya and Tibetan Plateau. Climate data derived from some terrestrial and marine sediments from the Neogene suggests the onset and intensification of the SAM to a near-modern state occurred during the Miocene, while modelling and other terrestrial proxies point to a much earlier origin for the proto-East Asia monsoon (EAM) and proto-SAM. Angiosperm leaves, particularly dicot leaves, provide a good indication of prevailing climatic conditions as a result of key adaptations in their leaf structure. Here we use Climate Leaf Analysis Multivariate Program (CLAMP) in conjunction with general circulation models to decode the Lower (~13–11 Ma) and Middle (9.5–6.8 Ma) Siwalik climate signal inherent in the physiognomy of fossil leaves. The reconstructed climate data indicates that the Middle Siwalik was warmer and wetter than the Lower Siwalik, particularly in the cooler part the year. The leaf physiognomy of Lower and Middle Siwalik assemblages is indistinguishable to that of the modern leaf assemblages, which are influenced by today's SAM climate. This shows that the SAM was already well established as an independent domain during the late middle Miocene (~13–11 Ma) and has remained nearly the same from the perspective of leaf adaptations since then. A quantitative monsoon intensity index indicates an intensified monsoon during the late Miocene (9.5–6.8 Ma), a finding replicated by climate modelling.

Latest Cretaceous (Maastrichtian) climate of the Koryak Upland of North-East Russia based on a quantitative analysis of a palaeo-polar flora

We describe fossil plant assemblages from the late Maastrichtian Kakanaut Formation of the Koryak Upland, North-East of Russia, which represent a high (75oN) palaeolatitude flora. The flora contains about 40 species, including liverworts, horsetails, ferns, cycadophytes, ginkgos, conifers and angiosperms. Angiosperms and conifers predominate and, unusually, the flora contains typical Cretaceous taxa admixed with elements that are more characteristic of the Paleocene. Reconstruction of the palaeoclimate in the Kakanaut area was made using the Climate Leaf Analysis Multivariate Program (CLAMP) employing a recently developed calibration that yields 23 different climate variables. Analysis was made based on 21 morphotypes of woody dicotyledonous plants from the Kakanaut flora. The analysis indicated a mean annual temperature of 12.2 ± 2.0 °C, a warmest month mean temperature of 20.6 ± 2.5 °C, a coldest month mean temperature of 4.8 ± 3.2 °C. The growing season lasted approximately 7 months, during which there was almost 1 m of precipitation. This and other indicators (relative humidity, vapour pressure deficit and potential evapotranspiration) all suggest a year-round humid regime. The winter temperatures suggest occasional mild frosts in this near sea level setting, so that at higher elevations freezing conditions would have been more persistent. These results throw new light on the living and breeding conditions of diverse latest Cretaceous Arctic dinosaur populations as represented by numerous skeletal and egg remains associated with the plants.

Diverse epiphyllous fungi on Cunninghamia leaves from the Oligocene of South China and their paleoecological and paleoclimatic implications

AbstractThe unique co‐occurrence of thyriothecia belonging to three fossil genera of epiphyllous fungi, Stomiopeltites Alvin & Muir (Micropeltidaceae), Callimothallus Dilcher, and Trichothyrites Rosendahl (Microthyriaceae), are reported on the leaves of the same host plant, Cunninghamia shangcunica Kodrul, Gordenko & Sokolova from the Oligocene Shangcun Formation of the Maoming Basin, South China. In China, Stomiopeltites is identified for the first time, Callimothallus is known from the Oligocene and Miocene of Guangxi and Zhejiang provinces, and Trichothyrites previously has been found only in the Eocene palynological assemblages of the Maoming Basin. The presence of abundant and diverse epiphyllous micromycetes, together with the taxonomic composition of the Shangcun megaflora and pollen assemblage, as well as quantitative climatic estimates obtained using Climate Leaf Analysis Multivariate Program, confirm the existence of a warm and humid climate in this region during the late early Oligocene. The geographic and stratigraphic distributions, comparisons with extant analogues, as well as ecological and paleoclimatic implications of the fossil fungi are discussed.

Climatic evolution in Western Europe during the Cenozoic: insights from historical collections using leaf physiognomy

A major climatic shift, from a glasshouse world to a colder climate with well-developed ice sheets, occurred during the Cenozoic. Such a transition is recorded in both marine and terrestrial records. The latter is more fragmentary and thus comparatively less well known from a climatic point of view. Leaves are abundant fossil remains, which can be used as terrestrial climatic proxies. In this study, several historical collections from France and Belgium were re-investigated. We applied the Climate Leaf Analysis Multivariate Program in order to document the regional past climate from middle Paleocene to middle Miocene in Western Europe. Our analysis suggest relatively cooler conditions during middle Paleocene, followed by a gradual increase of mean annual temperature and precipitation seasonality during late Paleocene; increased temperature seasonality rather than a global cooling at the Eocene-Oligocene transition; an increase of temperature between early and late Oligocene and warm temperate climate in Western Europe similar to other parts of Europe during middle Miocene. These results are broadly consistent with the global trends observed through the Cenozoic era in the marine record. This study provides new quantitative paleoclimatic estimates for various key periods of the Cenozoic era in Western Europe. The consistency of our results with previous studies based on multiples proxies is in favor of the use of historical collections to reconstruct past climates, as long as sufficient sampling is provided.

The Kanaka Creek fossil flora (Huntingdon Formation), British Columbia, Canada — paleoenvironment and evidence for Paleocene age using palynology and macroflora

Paleogene sediments of the Huntingdon Formation, a correlative to the Chuckanut Formation of neighbouring Washington State, USA, are exposed in the Greater Vancouver area, British Columbia, Canada. Palynology and plant macrofossils suggest the Kanaka Creek section is Paleocene rather than Eocene in age. Detrital zircon dating is less decisive, yet indicates the Kanaka rocks are no older than Maastrichtian. Analyses of plant macro- and micro-fossils suggest an early to middle Paleocene age for the Kanaka fossil flora. Paleocene indicators include macrofossils such as Platanus bella, Archeampelos, Hamamelites inequalis, and Ditaxocladus, and pollen taxa such as Paraalnipollenites, Triporopollenites mullensis, and Duplopollis. Paleogene taxa such as Woodwardia maxonii, Macclintockia, and Glyptostrobus dominate the flora. Fungal spores including the Late Cretaceous Pesavis parva and the Paleogene Pesavis tagluensis are notable age indicators. Physiognomy of 41 angiosperm leaf morphotypes from Kanaka Creek yields mean annual temperatures in the microthermal to lower mesothermal range (11.2 ± 4.3 to 14.6 ± 2.7 °C from leaf margin analysis; 14.8 ± 2.1 °C from Climate Leaf Analysis Multivariate Program), with mild winters (cold month mean temperature 3.9 ± 3.4 °C). Paleoclimate was cooler than the upper Paleocene and Eocene members of the Chuckanut Formation. Mean annual precipitation is estimated at ∼140 cm with large uncertainties. The Kanaka paleoflora is reconstructed as a mixed conifer–broadleaf forest, sharing common taxa with other western North American Paleocene floras and growing in a temperate moist climate. Kanaka Creek is a rare coastal Paleocene plant locality that provides new insights into coastal vegetation and climate prior to the Paleocene–Eocene Thermal Maximum.