ORCID Profile
0000-0002-8569-9695
Current Organisation
Brandon University
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Publisher: Springer Science and Business Media LLC
Date: 06-2009
DOI: 10.1038/NATURE08069
Abstract: A profound global climate shift took place at the Eocene-Oligocene transition ( approximately 33.5 million years ago) when Cretaceous/early Palaeogene greenhouse conditions gave way to icehouse conditions. During this interval, changes in the Earth's orbit and a long-term drop in atmospheric carbon dioxide concentrations resulted in both the growth of Antarctic ice sheets to approximately their modern size and the appearance of Northern Hemisphere glacial ice. However, palaeoclimatic studies of this interval are contradictory: although some analyses indicate no major climatic changes, others imply cooler temperatures, increased seasonality and/or aridity. Climatic conditions in high northern latitudes over this interval are particularly poorly known. Here we present northern high-latitude terrestrial climate estimates for the Eocene to Oligocene interval, based on bioclimatic analysis of terrestrially derived spore and pollen assemblages preserved in marine sediments from the Norwegian-Greenland Sea. Our data indicate a cooling of approximately 5 degrees C in cold-month (winter) mean temperatures to 0-2 degrees C, and a concomitant increased seasonality before the Oi-1 glaciation event. These data indicate that a cooling component is indeed incorporated in the delta(18)O isotope shift across the Eocene-Oligocene transition. However, the relatively warm summer temperatures at that time mean that continental ice on East Greenland was probably restricted to alpine outlet glaciers.
Publisher: University of Chicago Press
Date: 02-2020
DOI: 10.1086/706450
Publisher: Informa UK Limited
Date: 07-06-2014
Publisher: Elsevier BV
Date: 04-2016
Publisher: Springer Science and Business Media LLC
Date: 24-06-2017
Publisher: Elsevier BV
Date: 02-2023
Publisher: Copernicus GmbH
Date: 22-10-2013
Publisher: Elsevier BV
Date: 12-2018
Publisher: Canadian Science Publishing
Date: 02-2005
DOI: 10.1139/E04-100
Abstract: The late Early to early Middle Eocene Okanagan Highlands fossil sites, spanning ~1000 km northsouth (northeastern Washington State, southern British Columbia) provide an opportunity to reconstruct biotic communities across a broad upland landscape during the warmest part of the Cenozoic. Plant taxa from these fossil sites are characteristic of the modern eastern North American deciduous forest zone, principally the mixed mesophytic forest, but also include extinct taxa, taxa known only from eastern Asian mesothermal forests, and a small number of taxa restricted to the present-day North American west coast coniferous biome. In this preliminary report, paleoclimates and forest types are reconstructed using collections from Republic in Washington State, USA., and Princeton, Quilchena, Falkland, McAbee, Hat Creek, Horsefly, and Driftwood Canyon in British Columbia, Canada. Both leaf margin analysis (LMA) and quantitative bioclimatic analysis of identified nearest living relatives of megaflora indicated upper microthermal to lower mesothermal moist environments (MAT ~1015 °C, CMMT 0 °C, MAP 100 cm/year). Some taxa common to most sites suggest cool conditions (e.g., Abies, other Pinaceae Alnus, other Betulaceae). However, all floras contain a substantive broadleaf deciduous element (e.g., Fagaceae, Juglandaceae) and conifers (e.g., Metasequoia) with the bioclimatic analysis yielding slightly higher MAT than LMA. Thermophilic (principally mesothermal) taxa include various insects, the aquatic fern Azolla, palms, the banana relative Ensete, taxodiaceous conifers, Eucommia and Gordonia, taxa which may have occurred near their climatic limits. The mixture of thermophilic and temperate insect and plant taxa indicates low-temperature seasonality (i.e., highly equable climate).
Publisher: Copernicus GmbH
Date: 16-04-2014
Abstract: Abstract. The Paleocene–Eocene Thermal Maximum (PETM) represents a ~170 kyr episode of anomalous global warmth ~56 Ma ago. The PETM is associated with rapid and massive injections of 13C-depleted carbon into the ocean–atmosphere system reflected as a prominent negative carbon isotope excursion (CIE) in sedimentary components. Earth's surface and deep ocean waters warmed by ~5 °C, of which part may have occurred prior to the CIE. However, few records document continental climatic trends and changes in seasonality have not been documented. Here we present the first high-resolution vegetation and paleoclimate reconstructions for the PETM, based on nearest living relative analysis of terrestrially derived spore and pollen assemblages preserved in an expanded section from the central North Sea. Our data indicate reductions in boreal conifers and an increase in mesothermal to megathermal taxa, reflecting a shift towards wetter and warmer climate. We also record an increase in summer temperatures, greater in magnitude than the rise in mean annual temperature changes, and a shift to a summer-wet seasonality. Within the CIE, vegetation varies significantly with initial increases in epiphytic and climbing ferns, and development of extensive wetlands, followed by abundance of Carya spp. indicative of broadleaf forest colonization. Critically, the change in vegetation we report occurs prior to the CIE, and is concomitant with anomalous marine ecological change, as represented by the occurrence of Apectodinium augustum. This suggests that lifications of seasonal extremes triggered carbon injection.
Publisher: Elsevier BV
Date: 08-2003
Publisher: Elsevier BV
Date: 02-2020
Publisher: Geological Society of America
Date: 06-2012
DOI: 10.1130/G33384Y.1
Publisher: Geological Society of America
Date: 1996
Publisher: University of Chicago Press
Date: 03-2023
DOI: 10.1086/724156
Publisher: Wiley
Date: 25-11-2017
Abstract: High-throughput sequencing methods promise to improve our ability to infer the evolutionary histories of lineages and to delimit species. These are exciting prospects for the study of Australian vertebrates, a group comprised of many globally unique lineages with a long history of isolation. The evolutionary relationships within many of these lineages have been difficult to resolve with small numbers of loci, and we now know that many lineages also exhibit substantial cryptic ersity. Here, we present a set of phylogenetically erse transcriptome resources to enable exon-based sequence capture studies of Australian vertebrates, including transcriptome sequences for four species of birds, four frogs, seven lizards and seven mammals. We also use exon data from the marsupial transcriptomes we generated to examine an approach for choosing a moderate number (dozens or hundreds) of phylogenetically informative exons based on a single transcriptome sequence, and a relatively distant reference genome.
Publisher: Elsevier BV
Date: 08-2020
Publisher: Wiley
Date: 26-01-2022
Publisher: Geological Society of America
Date: 07-2010
DOI: 10.1130/G30815.1
Publisher: Schweizerbart
Date: 19-12-2002
Publisher: Geological Society of America
Date: 1998
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/BT04032
Abstract: An Early Eocene plant assemblage from near the summit of Mt Hotham, Victoria, is described, using a combination of macro- and microfossils, especially cuticles. This is important since no other Australian macrofossil sites from this time, when environmental conditions are believed to have been the warmest of the Cenozoic, have been described in detail. The nature of the flora and vegetation supports geological evidence that the site was upland (approximately 800 m above sea level) at this time, with climatic conditions similar to those now experienced in regions such as the Atherton Tablelands in Queensland and mid-montane Papua New Guinea. The vegetation was probably a form of rainforest dominated by mesotherm elements, with abundant ferns including Gleicheniaceae and the tree ferns Cnemidaria, Cyathea and Dicksonia. Gymnosperms included Araucariaceae (Agathis) and Podocarpaceae (at least Acmopyle and Dacrydium). Angiosperms were erse in Lauraceae (at least nine species including probably Cryptocarya, Endiandra and Litsea) and Proteaceae (at least nine species including probably Musgravea and Darlingia). Other angiosperms included Cunoniaceae, Gymnostoma (Casuarinaceae), Diospyros-like Ebenaceae, and the vine Cissocarpus (Vitaceae). Nothofagus was rare or absent from the Mt Hotham region at this time, as no macrofossil evidence was found, and pollen percentages were very low.
Publisher: Canadian Science Publishing
Date: 08-2013
Abstract: A flora from Thomas Ranch near Princeton, British Columbia, Canada, is assessed for bio ersity and paleoclimate. This latest Early to early Middle Eocene flora occurs in the Allenby Formation. Seventy-six megafossil morphotypes have been recognized, representing at least 62 species, with 29 identified to genus or species. Common taxa include Ginkgo L., Metasequoia Miki, Sequoia Endl., Abies Mill., Pinus L., Pseudolarix Gordon, Acer L., Alnus Mill., Betula L., Fagus L., Sassafras J Presl, Macginitiea Wolfe & Wehr, Prunus L., and Ulmus L. More than 70 pollen and spore types are recognized, 32 of which are assignable to family or genus. The microflora is dominated by conifers (85%–97% abundance), with Betulaceae accounting for most of the angiosperms. The Climate Leaf Analysis Multivariate Program (CLAMP) calculates a mean annual temperature (MAT) of 9.0 ± 1.7 °C and bioclimatic analysis (BA) calculates a MAT of 12.8 ± 2.5 °C. Coldest month mean temperature (CMMT) was °C. Mean annual precipitation (MAP) was cm/year but is estimated with high uncertainty. Both the CLAMP and BA estimates are at the low end of the MAT range previously published for other Okanagan Highland localities, indicating a temperate climate consistent with a mixed conifer–deciduous forest.
Publisher: Cambridge University Press (CUP)
Date: 07-2013
DOI: 10.1666/12-129
Abstract: The scorpionfly (Mecoptera) superfamily Panorpoidea underwent an Eocene radiation, replacing the extinct Mesozoic orthophlebiid grade and reaching its greatest family-level ersity: Panorpidae, Panorpodidae, Austropanorpidae, Holcorpidae, Dinopanorpidae, and a new family proposed here, the Eorpidae. Only the Panorpidae and Panorpodidae survived the Eocene and persist to the present day. This cluster of family extinctions is exceptional within Cenozoic insects. The Eorpidae includes at least one new genus and three new species described here from four localities of the early Eocene Okanagan Highlands of British Columbia, Canada, and Washington, U.S.A.: Eorpa ypsipeda n. gen. n. sp. (McAbee and possibly Falkland, BC, Canada and Republic, WA, U.S.A.), Eorpa elverumi n. gen. n. sp. (Republic), and Eorpa jurgeni n. gen. n. sp. (Quilchena, BC). Some of the other fragmentary and poorly preserved specimens might represent further new species. We propose that the apex of Panorpoid family ersity ended by pressures from post-Eocene icehouse world climatic stress and the rise to ecological dominance of ants, some of which would have provided strong competition in scavenging for dead arthropods.
Publisher: Wiley
Date: 08-04-2005
Publisher: Proceedings of the National Academy of Sciences
Date: 12-05-2014
Abstract: Elevated CO 2 combined with globally warm temperatures in the Eocene make its climate ideal for understanding modern global warming and its biotic consequences. Globally low temperature seasonality—the relationship between winter and mean annual temperatures—has been proposed as key to differential Eocene bio ersity and community patterns. Palms are important winter temperature indicators by their sensitivity to frost however, their presence in paleocommunities may be masked by taphonomic constraints and identification difficulties. We used fossil obligate palm-feeding beetles to establish the presence of palms in a cool upland in midlatitude western North America. In this way, we provide a more precise characterization of climate during an important interval of the emergence of modern ecosystems.
Publisher: Springer Science and Business Media LLC
Date: 21-10-2011
Publisher: Informa UK Limited
Date: 26-10-2021
Publisher: Copernicus GmbH
Date: 11-01-2018
DOI: 10.5194/BG-2017-511
Abstract: Abstract. Mid-Oligocene to Early Miocene terrestrial palynomorphs from the New Jersey hinterland (eastern North America: IODP-Expedition 313) were analysed, using light microscopy and scanning electron microscopy, to infer altitudinal spatial and long-term temporal vegetation migration in context of global climate change. The mesophytic forest was the most widespread vegetation type in the hinterland, with Quercus (Group Quercus, Quercus/Lobatae and aff. Group Protobalanus) being the dominant taxon. Pollen grains of the extinct genus Eotrigonobalanus (Fagaceae) are documented. To infer possible topographic palaeovegetation movements during the selected time interval terrestrial palynomorphs were assigned to six vegetation units. Relative abundances of vegetation units show weak temporal and spatial fluctuations, with the sum of bisaccate pollen grains being most pronounced. Periodic changes in vegetation units suggest movements of the plant cover responding to orbital-scale glacial-interglacial changes of the Oligocene and early Miocene. Relative abundances of several taxa (e.g. Carya) did not change significantly during the Oligocene, but alterations are recognizable when compared with an already published late Middle Miocene record from the same area, probably indicating biotic responds to environment change. A pollen-based bioclimatic analysis with four standard parameters (mean annual temperature, mean temperatures of the coldest and warmest month, mean annual precipitation) was performed to reconstruct palaeoclimatic changes indicating weak fluctuations in temperature and precipitation.
Publisher: Geological Society of America
Date: 2010
DOI: 10.1130/G30218.1
Publisher: Springer Science and Business Media LLC
Date: 16-03-2018
DOI: 10.1038/S41598-018-23147-2
Abstract: Fossil palms provide qualitative evidence of (sub-) tropical conditions and frost-free winters in the geological past, including modern cold climate regions (e.g., boreal, or polar climates). The freeze intolerance of palms varies across different organs and life stages, with seedlings in particular less tolerant of sub-zero temperatures than adult plants, limiting successful establishment of populations while permitting adult palms to survive in cultivation outside their natural ranges. Quantitatively, palms indicate minimum cold month mean temperature (CMMT) at 2–8 °C in palaeoclimate reconstructions. These data have accentuated model-proxy mismatches for high latitudes during Paleogene hyperthermals when palms expanded poleward in both hemispheres. We constructed a manually filtered dataset of ,000 georeferenced Arecaceae records, by eliminating cultivars. Statistically derived mean annual temperature, mean annual temperature range, and CMMT thresholds for the Arecaceae and lower rank subfamilies and tribes reveal large differences in temperature sensitivity depending on lower taxonomic classification. Cold tolerant tribes such as the Trachycarpeae produce thresholds as low as CMMT ≥ 2.2 °C. However, within the palm family, CMMT 5 °C is anomalous. Moreover, palm expansion into temperate biomes is likely a post-Palaeogene event. We recognize a CMMT ≥ 5.2 °C threshold for the palm family, unless a lower taxonomic rank can be assigned.
Publisher: Geological Society of America
Date: 03-12-2010
DOI: 10.1130/G31208.1
Publisher: Copernicus GmbH
Date: 25-08-2014
Abstract: Abstract. We investigated the palynology of sediment cores from Site M0027 of IODP (Integrated Ocean Drilling Program) Expedition 313 on the New Jersey shallow shelf to examine vegetation and climate dynamics on the east coast of North America between 33 and 13 million years ago and to assess the impact of over-regional climate events on the region. Palynological results are complemented with pollen-based quantitative climate reconstructions. Our results indicate that the hinterland vegetation of the New Jersey shelf was characterized by oak–hickory forests in the lowlands and conifer-dominated vegetation in the highlands from the early Oligocene to the middle Miocene. The Oligocene witnessed several expansions of conifer forest, probably related to cooling events. The pollen-based climate data imply an increase in annual temperatures from ∼11.5 °C to more than 16 °C during the Oligocene. The Mi-1 cooling event at the onset of the Miocene is reflected by an expansion of conifers and mean annual temperature decrease of ∼4 °C, from ∼16 °C to ∼12 °C around 23 million years before present. Relatively low annual temperatures are also recorded for several s les during an interval around ∼20 million years before present, which may reflect the Mi-1a and the Mi-1aa cooling events. Generally, the Miocene ecosystem and climate conditions were very similar to those of the Oligocene. Miocene grasslands, as known from other areas in the USA during that time period, are not evident for the hinterland of the New Jersey shelf, possibly reflecting moisture from the proto-Gulf Stream. The palaeovegetation data reveal stable conditions during the mid-Miocene climatic optimum at ∼15 million years before present, with only a minor increase in deciduous–evergreen mixed forest taxa and a decrease in sw forest taxa. Pollen-based annual temperature reconstructions show average annual temperatures of ∼14 °C during the mid-Miocene climatic optimum, ∼2 °C higher than today, but ∼1.5 °C lower than preceding and following phases of the Miocene. We conclude that vegetation and regional climate in the hinterland of the New Jersey shelf did not react as sensitively to Oligocene and Miocene climate changes as other regions in North America or Europe due to the moderating effects of the North Atlantic. An additional explanation for the relatively low regional temperatures reconstructed for the mid-Miocene climatic optimum could be an uplift of the Appalachian Mountains during the Miocene, which would also have influenced the catchment area of our pollen record.
Publisher: Informa UK Limited
Date: 16-05-2017
Publisher: Informa UK Limited
Date: 03-2000
Publisher: The Royal Society
Date: 06-2020
DOI: 10.1098/RSOS.200305
Abstract: The exceptionally well-preserved holotype of the armoured dinosaur Borealopelta markmitchelli (Ornithischia Nodosauridae) from the Early Cretaceous (Clearwater Formation) of northern Alberta preserves a distinct mass within the abdominal cavity. Fourteen independent criteria (including: co-allochthony, anatomical position, gastroliths) support the interpretation of this mass as ingested stomach contents—a cololite. Palynomorphs in the cololite are a subset of the more erse external s le. Analysis of the cololite documents well-preserved plant material dominated by leaf tissue (88%), including intact sporangia, leaf cross-sections and cuticle, but also including stems, wood and charcoal. The leaf fraction is dominated (85%) by leptosporangiate ferns (subclass Polypodiidae), with low cycad–cycadophyte (3%) and trace conifer foliage. These data represent the most well-supported and detailed direct evidence of diet in an herbivorous dinosaur. Details of the dietary palaeoecology of this nodosaur are revealed, including: selective feeding on ferns preferential ingestion of leptosporangiate ferns to the exclusion of Osmundaceae and eusporangiate ferns such as Marattiaceae and incidental consumption of cycad–cycadophyte and conifer leaves. The presence of significant (6%) charcoal may represent the dietary use of recently burned conifer forest undergoing fern succession, early evidence of a fire succession ecology, as is associated with many modern large herbivores.
Publisher: Elsevier BV
Date: 11-2017
Publisher: Geological Society of America
Date: 05-2017
DOI: 10.1130/G39002.1
Publisher: Geological Society of America
Date: 2008
DOI: 10.1130/G24332A.1
Publisher: Elsevier BV
Date: 02-2013
Publisher: University of New Brunswick Libraries - UNB
Date: 20-04-2017
DOI: 10.12789/GEOCANJ.2017.44.116
Abstract: This short summary presents selected results of an ongoing investigation into the feedbacks that contribute to lified Arctic warming. The consequences of warming for Arctic bio ersity and landscape response to global warmth are currently being interpreted. Arctic North American records of large-scale landscape and paleoenvironmental change during the Pliocene are exquisitely preserved and locked in permafrost, providing an opportunity for paleoenvironmental and faunal reconstruction with unprecedented quality and resolution. During a period of mean global temperatures only ~2.5°C above modern, the Pliocene molecular, isotopic, tree-ring, paleofaunal, and paleofloral records indicate that the high Arctic mean annual temperature was 11°C–19°C above modern values, pointing to a much shallower latitudinal temperature gradient than exists today. It appears that the intense Neogene warming caused thawing and weathering to liberate sediment and create a continuous and thick ( .5 km in places) clastic wedge from at least Banks Island to Meighen Island to form a coastal plain that provided a highway for camels and other mammals to migrate and evolve in the high Arctic. In this summary we highlight the opportunities that exist for research on these and related topics with the PoLAR-FIT community.RÉSUMÉCe bref résumé présente les résultats choisis d'une enquête en cours sur les déclencheurs qui contribuent à l’ lification du réchauffement de l'Arctique. Les conséquences du réchauffement sur la bio ersité arctique et de la réponse du paysage au réchauffement climatique sont en cours d’être interprété. Des dossiers nord-américains de paysage à grande échelle et le changement paléoenvironnementales durant le Pliocène sont exceptionnellement préservés et scellées dans un état de congélation qui fournissant une occasion pour la reconstruction paléoenvironnementale et faunistique avec une qualité et une résolution sans précédent. Pendent une période de réchauffement global seulement ~2,5°C au-dessus de moderne les dossiers, moléculaire, isotopique, annaux de croissance, paléofaunistique et paléovégétation indiquent que l'Arctique a connu une augmentation de la température annuelle moyenne de 11°C–19°C au-dessus de moderne, en montrant un inferieur gradient de température latitudinal qu'aujourd'hui. Il semble que le réchauffement intense pendent le Néogène a provoqué la décongélation et erosion pour libérer les sédiments et créer une plaine côtière continuel et épaisse ( 2,5 km dans lieux) qui a fourni une route pour les chameaux et autres mammifères pour migrer et évoluer dans l’Haut-Arctique. Dans ce résumé, nous soulignons les opportunités qui existent pour la recherche sur ces sujets et les sujets connexes avec la communauté PoLAR-FIT.
Publisher: Canadian Science Publishing
Date: 06-2016
Abstract: The Quilchena fossil locality is dated (51.5 ± 0.4 Ma) to the Early Eocene Climatic Optimum, and this locality is reconstructed as the warmest and wettest of the Early Eocene upland sites from the Okanagan Highlands of British Columbia and northern Washington State. Mean annual temperature (MAT) is estimated from leaf margin analysis, using 55 dicot morphotypes, as 16.2 ± 2.1 °C/14.6 ± 4.8 °C. Using bioclimatic analysis of 45 nearest living relatives, a moist mesothermal climate is indicated (MAT 12.7–16.6 °C cold month mean temperature (CMMT) 3.5–7.9 °C mean annual precipitation (MAP) 103–157 cm/year. Leaf size analysis estimates MAP at 121 ± 39 cm/year. Estimates from the climate leaf analysis multivariate program corroborate these results, although with a slightly cooler MAT (13.3 ± 2.1 °C). Plants that support an interpretation of warm winters with minimal or no frost include Azolla, Glyptostrobus, Taxodium, Keteleeria, Pseudolarix, Eucommia, Dipteronia, Hovenia, Ternstroemia, and others. These thermophilous elements occur together with temperate genera such as Alnus, Betula, Ulmus, Calocedrus, and Fraxinus. Palynological assemblages at Quilchena are dominated by bisaccate conifers and Cupressaceae. Common angiosperms include Ulmus type, triporates, Pterocarya, and Alnus. Insect fossils at Quilchena that today inhabit tropical and subtropical regions also support warm and equable climate without significant frost, and include obligate palm-feeding beetles (Pachymerina), which indicate CMMT perhaps as high as 8 °C. These are found together with temperate aphids, wasps, giant lacewings, brown lacewings, and a panorpoid scorpionfly, supporting an interpretation of equable climatic conditions during the Early Eocene Climatic Optimum.
Publisher: Ottawa Field-Naturalists' Club
Date: 20-02-2023
Abstract: Ferns are important components of the bio ersity of wet forests across Canada, and the fossil record offers insights into the origins of fern ersity and biogeography. In 1967, Driftwood Canyon Provincial Park in north-central British Columbia was declared an Eocene Epoch plant, insect, fish, bird, and mammal fossil site of national scientific significance to preserve the Driftwood Creek fossil beds. The fossil plants from this important fossil site remain largely unknown. Here, a first record of a beech fern from the Eocene of British Columbia—morphologically comparable to the Phegopteris connectilis group—is illustrated, further revealing the past bio ersity of ancient British Columbia. The absence of sori and other key anatomical characters prevents definitive identification. Today, the circumpolar to temperate species Northern Beech Fern (Phegopteris connectilis) is widespread across British Columbia, occurring in wet coniferous forests other members of the P. connectilis group also occur in temperate climates.
Publisher: Geological Society of America
Date: 09-12-2011
DOI: 10.1130/B30571.1
Publisher: Canadian Science Publishing
Date: 06-2016
Abstract: Early Eocene fossil floras from British Columbia are a rich resource for reconstructing western North American early Cenozoic climate. The best known of these floras reflect cooler (MAT ≤ 15 °C) upland forest communities in contrast to coeval (MAT ≥ 18 °C) forests in lowland western North American sites. Of particular interest is whether Early Eocene climates were monsoonal (highly seasonal precipitation). The McAbee site is a 52.9 ± 0.83 Ma 0.5 km outcrop of bedded lacustrine shale interbedded with volcanic ash. In this report two historical megaflora collections that were collected independently from different stratigraphic levels and (or) laterally separated by ∼100–200 m in the 1980s (University of Saskatchewan) and 2000s (Brandon University) are investigated to (i) assess whether they represent the same leaf population, (ii) assess whether a combined collection yields more precise climate estimates, and (iii) reconstruct paleoclimate to assess the character of regional Early Eocene precipitation seasonality. Combined, the two s les yielded 43 dicot leaf morphotypes. Analysis of leaf size distribution using ANOVA showed no difference between the two s les, and thus they were combined for climate analysis. Climate analysis using leaf physiognomy agrees with previous estimates for McAbee and other regional megafloras, indicating a warm (MAT ∼8–13 °C), mild (CMMT ∼5 °C), moist (MAP 100 cm/year) ever-wet, non-monsoonal climate. Additionally, we recommend that climate analyses derived from leaf fossils should be based on s les collected within a stratigraphically constrained quarry area to capture a snapshot of climate in time rather than time-averaged estimates derived from multiple quarry sites representing different stratigraphic levels within a fossil site.
Publisher: Canadian Science Publishing
Date: 02-2005
DOI: 10.1139/E04-095
Abstract: Palynofloras from the middle Early to early Middle Eocene Okanagan Highlands (northern Washington State and southern British Columbia) are used to reconstruct vegetation across a broad upland Eocene landscape. In this preliminary report, forest floristic composition is reconstructed using palynological analysis of sediments from Republic, Washington localities of the Allenby Formation in the Princeton region (Hospital Hill, One Mile Creek and Summers Creek Road), Hat Creek, McAbee, Falkland, Horsefly, and Driftwood Canyon, British Columbia. Wind-dispersed taxa were dominant in all s les, consistent with floras preserved in lacustrine and paludal depositional environments. Pseudolarix was dominant in five of the floras, but Abies (Falkland) or Ulmus (Republic Corner Lot site) were dominant in in idual s les for some floras. Betulaceae were dominant for McAbee (Alnus) and Allenby Formation (Betula), matching megafloral data for these sites. Some taxa common to most sites suggest cool conditions (e.g., Abies, other Pinaceae Alnus, other Betulaceae). However, all floras contained a substantive broad-leaved deciduous element (e.g., Fagaceae, Juglandaceae) and conifers (e.g., Metasequoia) indicative of mesothermal conditions. Palms were only abundant in the Hat Creek coal flora, with very low counts recorded for the Falkland, McAbee, and Allenby Formation sites, suggesting that they were rare in much of the landscape and likely restricted to specialized habitats. Thermophilic (principally mesothermal) taxa, including palms (five sites) and "taxodiaceous" conifers, may have occurred at their climatic limits. The limiting factor controlling the regional distribution of thermophilic flora, which include primarily wetlands taxa, may be either climatic or edaphic.
Publisher: Canadian Science Publishing
Date: 06-2016
Abstract: A series of Eocene lake shale deposits from British Columbia, coined the Okanagan Highlands, are dated from associated volcanic ash as mostly from the Early Eocene Climatic Optimum (EECO), the longest persisting of the early Paleogene hyperthermals. In this report we focus on high-resolution palynological s ling of short sequences for the Falkland site to determine if they record centennial- or millennial-scale vegetation change during the EECO. The Falkland shales consist of alternating dark- and light-coloured irregular laminae, along with interleaved tephras from volcanic eruptions. At this site it is apparent that deposition occurred over several millennia. Pollen grains were counted under light microscopy using a standard transect method, with clustering analysis determining whether the data show any long-term trends in plant representation and abundance. Our data show that regional vegetation was impacted by millennial- to centennial-scale climatic variability, as well as the effects of volcanic eruptions. At Falkland there appears to be alterations in vegetation assemblages (birch – golden larch association to fir–spruce) that reflect longer-term (centennial to millennial) climatic transitions (warm/wet to cool/dry). Within this sequence, a period of environmental disturbance (reflected in the presence of multiple volcanic ash layers, wave ripple marks, and a fish-kill layer) has a marked impact on vegetation representation, with a dramatic increase in Abies and Picea pollen at the expense of Alnus and Betula, which do eventually recover. These results suggest mid-latitude millennial-scale climate oscillations in the waning period of the EECO of a similar magnitude to Holocene variability.
Publisher: Canadian Science Publishing
Date: 2007
DOI: 10.1139/B07-001
Abstract: Flowers and fruits of the Myrtaceae are described from the Middle Eocene Golden Grove locality of South Australia, and the taxon is here named Tristaniandra alleyi gen. et sp.nov. Flowers are pentamerous and perigynous, with sepals, petals, and stamens inserted on the rim of a hypanthium. Filaments are basally fused to form antepetalous stamen bundles, each consisting of about 6–8 stamens. The tricarpellate ovary becomes exserted on maturation, forming a partly exserted, dry fruit with loculicidal dehiscence. These features are typical of capsular-fruited members of the Myrtaceae in particular, taxa in the tribe Kanieae. While the characteristics of the fossils are not found within any one extant genus, the fossils show some similarity to living species of Tristaniopsis , although the staminal bundles are more comparable to those found in Tristania , which is only distantly related and has a rather different fruit. Capsular-fruited Myrtaceae are now primarily confined to Australasia, and appear to have had a Gondwanic origin in the latest Cretaceous to Paleogene. Nevertheless, as fossil flowers and fruits are rare, and infrafamilial identification of pollen and leaves is difficult, the Paleogene record of capsular Myrtaceae is largely equivocal. The Golden Grove fossils establish a record of the tribe Kanieae within Eocene coastal rainforest vegetation at paleolatitude 55°–58°S during a time of global warmth.
Publisher: Canadian Science Publishing
Date: 03-2020
Abstract: 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, Arche elos, 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.
Publisher: Elsevier BV
Date: 05-2003
Publisher: Geological Society of America
Date: 1995
Publisher: Unpublished
Date: 2016
Publisher: Wiley
Date: 03-09-2022
Publisher: Elsevier BV
Date: 03-1994
Publisher: Geological Society of America
Date: 2003
Publisher: Society for Sedimentary Geology
Date: 12-06-2014
Publisher: Canadian Science Publishing
Date: 09-2017
Abstract: We describe Eocene fossils of the tillodont Trogosus from the Allenby Formation in Princeton, British Columbia (B.C.), as well as teeth of Brontotheriina from the lower Australian Creek Formation near Quesnel, B.C. These fossils represent the only occurrence of Tillodontia and Brontotheriidae in B.C. Further, the presence of the largest species of Trogosus — T. latidens — as well as a smaller species identified only as Trogosus sp. supports a late early – early middle Eocene (Bridgerian) age for the Vermilion Bluffs Shale of the Allenby Formation. Based on their morphology and large size, the teeth referred here to Brontotheriina represent one of the larger, more derived brontothere genera, and suggest a Uintan–Chadronian (middle–late Eocene) age range for the lower Australian Creek Formation that is consistent with radiometric ages of underlying volcanic rocks. Paleobotanical data from sediments correlative to those that produced these Eocene mammal fossils suggest they inhabited forested landscapes interspersed with sw s and open water environments, under mild and wet temperate climates (mean annual temperature (MAT) ∼10–16 °C cold month mean temperature (CMMT) −4–4 °C mean annual precipitation (MAP) cm/year). These mixed conifer–broadleaf forests included tree genera typical of modern eastern North American forests (e.g., Tsuga, Acer, Fagus, and Sassafras), together with genera today restricted to east Asia (e.g., Metasequoia, Cercidiphyllum, Dipteronia, and Pterocarya). The paleobotanical evidence is consistent with the hypothesized habitats of both tillodonts and brontotheres.
Publisher: Canadian Science Publishing
Date: 06-2016
Abstract: The history of plant fossil collecting in the Okanagan (Okanogan) Highlands of British Columbia and northeastern Washington is closely intertwined with the history of geological surveys and mining activities from the 1870s onward. The first descriptions of fossil plants from British Columbia were published in 1870–1920 by J.W. Dawson, G.M. Dawson, and D.P. Penhallow. In the United States, fossil leaves and fish were first recognized at Republic, Washington, by miners in the early 1900s. Many early workers considered these floras to be of Oligocene or Miocene age. C.A. Arnold described Canadian occurrences of conifers and Azolla in the 1950s. Palynological studies in the 1960s by L.V. Hills, G.E. Rouse, and others and those of fossil fish by M.V.H. Wilson in the 1970–1980s provided the framework for paleobotanical research at several key localities. Permineralized plants were first described from the Princeton chert in the 1970s by C.N. Miller, J.F. Basinger, and others, followed by R.A. Stockey and her students. W.C. Wehr and K.R. Johnson revitalized the study of fossils at Republic with the discovery of a erse assemblage in 1977. In 1987, J.A. Wolfe and Wehr produced a United States Geological Survey monograph on Republic, and Wehr cofounded the Stonerose Interpretive Center as a venue for public collecting. Systematic studies of the Okanagan Highlands plants, as well as paleoecological and paleoclimate reconstructions from palynomorphs and leaf floras, continue to expand our understanding of this important Early Eocene assemblage.
Publisher: Elsevier BV
Date: 07-2019
Publisher: Society for Sedimentary Geology
Date: 31-05-2022
Abstract: The early Eocene Okanagan Highland fossil sites of Washington (USA) and British Columbia (Canada) contain exquisitely preserved plant and insect fossils that showcase a critical time and place in the evolution of the Northern Hemisphere temperate deciduous biome. A comprehensive understanding of the dynamics of fossil deposition and preservation at these sites is not fully resolved but is critical for reliable reconstructions of these ancient forests. To expand on previous interpretations (e.g., deep, stratified, anoxic lake bottoms) and address uncertainties about the environment of deposition (e.g., distance to shore, influence of diatoms), we analyzed sediment s les from three Okanagan Highland fossil sites—McAbee, Falkland, and Driftwood Canyon—for organic biomarkers, their stable carbon isotopic compositions, and glycerol dialkyl glycerol tetraethers (GDGTs at McAbee only). Terpenoids suggest relative trends in gymnosperm abundance between sites that agree with prior macrofossil evidence, though absolute values may overestimate local gymnosperm abundance. A combination of biomarker evidence indicates a predominantly autochthonous aquatic source (e.g., diatoms) for organic matter in shale and mudstone s les, even contributing to long chain n-alkanes and likely to branched GDGTs, which are often assumed to be terrestrially sourced. In combination with biomarker evidence for anoxia and stratification, fossiliferous shales are interpreted to have been deposited offshore in deep and mesotrophic lakes that were thermally stratified with an anoxic hypolimnion, away from in-flowing tributaries, while a coal horizon at Driftwood Canyon was deposited in a shallower, eutrophic, anoxic wetland. Anoxic conditions likely minimized some degradation-based biases and promoted high quality fossil preservation. Deposition of sediment and fossil remains offshore and away from inflowing tributaries suggest fossil plants were locally sourced but highlights the need for careful consideration of transport-induced biases.
Publisher: Geological Society of America
Date: 1999
Publisher: Geological Society of America
Date: 29-03-2011
DOI: 10.1130/G31640.1
Publisher: Copernicus GmbH
Date: 13-12-2013
Abstract: Abstract. We have investigated the palynology of sediment cores from Sites M0027 and M0029 of IODP Expedition 313 on the New Jersey shallow shelf, east coast of North America, spanning an age range of 33 to 13 million years before present. Additionally, a pollen assemblage from the Pleistocene was examined. The palynological results were statistically analyzed and complemented with pollen-based quantitative climate reconstructions. Transport-related bias of the pollen assemblages was identified via analysis of the ratio of terrestrial to marine palynomorphs, and considered when interpreting palaeovegetation and palaeoclimate from the pollen data. Results indicate that from the early Oligocene to the middle Miocene, the hinterland vegetation of the New Jersey shelf was characterized by oak-hickory forests in the lowlands and conifer-dominated vegetation in the highlands. The Oligocene witnessed several expansions of conifer forest, probably related to cooling events. The pollen-based climate data imply an increase in annual temperatures from ~12 °C to more than 15 °C during the Oligocene. The Mi-1 cooling event at the onset of the Miocene is reflected by an expansion of conifers and an annual temperature decrease by almost 3 °C, from 15 °C to 12.5 °C around 23 million years before present. Particularly low annual temperatures are also recorded for an interval around ~20 million years before present, which probably reflects the Mi-1aa cooling event. Generally, the Miocene ecosystem and climate conditions were very similar to those of the Oligocene in the hinterland of the New Jersey shelf. Miocene grasslands, as known from other areas in the USA during that time period, are not evident for the hinterland of the New Jersey shelf. Surprisingly, the palaeovegetation data for the hinterland of the New Jersey shelf do not show extraordinary changes during the Mid-Miocene climatic optimum at ~15 million years before present, except for a minor increase in deciduous-evergreen mixed forest taxa and a decrease in sw forest taxa. Pollen-based annual temperature reconstructions show average annual temperatures of ~14 °C during the Mid-Miocene climatic optimum. We conclude that vegetation and regional climate in the hinterland of the New Jersey shelf did not react as sensitively to Oligocene and Miocene climate changes as other regions in North America or Europe. An additional explanation for the relatively low regional temperatures reconstructed for the Mid-Miocene climatic optimum could be an uplift of the Appalachian Mountains during the Miocene. The Pleistocene pollen assemblage probably derives from the Marine Isotope Chron 7 or 5e and shows climate conditions similar to present-day.
Publisher: CSIRO Publishing
Date: 1987
DOI: 10.1071/BT9870111
Abstract: The nomenclature of some Tertiary fossil Podocarpaceae is reviewed. Fossil Podocarpaceae from the Eocene Anglesea locality in Victoria are described and assigned to six species from five modern genera using cuticular and other vegetative morphology. Falcatifolium australis D. R. Greenwood is the first record for this genus in Australia. Dacrycarpus eocenica D. R. Greenwood, Podocarpus platyphyllum D. R. Greenwood and Prumnopitys lanceolata D. R. Greenwood are new species. Decussocarpus brownei (Selling) D. R. Greenwood and Prumnopitys aff. Pr. Tasmanica (Townrow) D. R. Greenwood have previously been recorded as megafossils from the Australian Tertiary. The ersity of Podocarpaceae recorded from Anglesea is far greater than in any modern Australian forests.
Publisher: Elsevier BV
Date: 04-1989
Publisher: Informa UK Limited
Date: 2005
Publisher: American Geophysical Union (AGU)
Date: 05-2022
DOI: 10.1029/2022PA004419
Abstract: The early Eocene (∼56–48 Myr ago) is characterized by high CO 2 estimates (1,200–2,500 ppmv) and elevated global temperatures (∼10°C–16°C higher than modern). However, the response of the hydrological cycle during the early Eocene is poorly constrained, especially in regions with sparse data coverage (e.g., Africa). Here, we present a study of African hydroclimate during the early Eocene, as simulated by an ensemble of state‐of‐the‐art climate models in the Deep‐time Model Intercomparison Project (DeepMIP). A comparison between the DeepMIP pre‐industrial simulations and modern observations suggests that model biases are model‐ and geographically dependent, however, these biases are reduced in the model ensemble mean. A comparison between the Eocene simulations and the pre‐industrial suggests that there is no obvious wetting or drying trend as the CO 2 increases. The results suggest that changes to the land sea mask (relative to modern) in the models may be responsible for the simulated increases in precipitation to the north of Eocene Africa. There is an increase in precipitation over equatorial and West Africa and associated drying over northern Africa as CO 2 rises. There are also important dynamical changes, with evidence that anticyclonic low‐level circulation is replaced by increased south‐westerly flow at high CO 2 levels. Lastly, a model‐data comparison using newly compiled quantitative climate estimates from paleobotanical proxy data suggests a marginally better fit with the reconstructions at lower levels of CO 2 .
Publisher: American Geophysical Union (AGU)
Date: 26-05-2022
DOI: 10.1029/2022PA004418
Abstract: During the early to middle Eocene, a mid‐to‐high latitudinal position and enhanced hydrological cycle in Australia would have contributed to a wetter and “greener” Australian continent where today arid to semi‐arid climates dominate. Here, we revisit 12 southern Australian plant megafossil sites from the early to middle Eocene to generate temperature, precipitation, and seasonality paleoclimate estimates, net primary productivity (NPP), and vegetation type, based on paleobotanical proxies and compare them to early Eocene global climate models. Temperature reconstructions are uniformly subtropical (mean annual, summer, and winter mean temperatures 19–21°C, 25–27°C, and 14–16°C, respectively), indicating that southern Australia was ∼5°C warmer than today, despite a ° poleward shift from its modern geographic location. Precipitation was less homogeneous than temperature, with mean annual precipitation of ∼60 cm over inland sites and cm over coastal sites. Precipitation may have been seasonal with the driest month receiving 2–7× less than the mean monthly precipitation. Proxy‐model comparison is favorable with a 1,680 ppm CO 2 concentration. However, in idual proxy reconstructions can disagree with models as well as with each other. In particular, seasonality reconstructions have systemic offsets. NPP estimates were higher than modern, implying a more homogenously “green” southern Australia in the early to middle Eocene when this part of Australia was at 48–64°S and larger carbon fluxes to and from the Australian biosphere. The most similar modern vegetation type is modern‐day eastern Australian subtropical forest, although the distance from coast and latitude may have led to vegetation heterogeneity.
Publisher: Elsevier BV
Date: 06-2022
Publisher: Elsevier BV
Date: 02-2017
Publisher: Informa UK Limited
Date: 27-01-2021
Publisher: American Geophysical Union (AGU)
Date: 06-2023
DOI: 10.1029/2022PA004542
Abstract: Earth's hydrological cycle is expected to intensify in response to global warming, with a “wet‐gets‐wetter, dry‐gets‐drier” response anticipated over the ocean. Subtropical regions (∼15°–30°N/S) are predicted to become drier, yet proxy evidence from past warm climates suggests these regions may be characterized by wetter conditions. Here we use an integrated data‐modeling approach to reconstruct global and zonal‐mean rainfall patterns during the early Eocene (∼56–48 million years ago). The Deep‐Time Model Intercomparison Project (DeepMIP) model ensemble indicates that the mid‐ (30°–60°N/S) and high‐latitudes ( °N/S) are characterized by a thermodynamically dominated hydrological response to warming and overall wetter conditions. The tropical band (0°–15°N/S) is also characterized by wetter conditions, with several DeepMIP models simulating narrowing of the Inter‐Tropical Convergence Zone. However, the latter is not evident from the proxy data. The subtropics are characterized by negative precipitation‐evaporation anomalies (i.e., drier conditions) in the DeepMIP models, but there is surprisingly large inter‐model variability in mean annual precipitation (MAP). Intriguingly, we find that models with weaker meridional temperature gradients (e.g., CESM, GFDL) are characterized by a reduction in subtropical moisture ergence, leading to an increase in MAP. These model simulations agree more closely with our new proxy‐derived precipitation reconstructions and other key climate metrics and imply that the early Eocene was characterized by reduced subtropical moisture ergence. If the meridional temperature gradient was even weaker than suggested by those DeepMIP models, circulation‐induced changes may have outcompeted thermodynamic changes, leading to wetter subtropics. This highlights the importance of accurately reconstructing zonal temperature gradients when reconstructing past rainfall patterns.
Publisher: Informa UK Limited
Date: 18-05-2022
Publisher: Springer Netherlands
Date: 1994
Publisher: The Royal Society
Date: 04-05-2011
Abstract: Early Eocene land bridges allowed numerous plant and animal species to cross between Europe and North America via the Arctic. While many species suited to prevailing cool Arctic climates would have been able to cross throughout much of this period, others would have found dispersal opportunities only during limited intervals when their requirements for higher temperatures were met. Here, we present Titanomyrma lubei gen. et sp. nov. from Wyoming, USA, a new giant (greater than 5 cm long) formiciine ant from the early Eocene (approx. 49.5 Ma) Green River Formation. We show that the extinct ant subfamily Formiciinae is only known from localities with an estimated mean annual temperature of about 20°C or greater, consistent with the tropical ranges of almost all of the largest living ant species. This is, to our knowledge, the first known formiciine of gigantic size in the Western Hemisphere and the first reported cross-Arctic dispersal by a thermophilic insect group. This implies intercontinental migration during one or more brief high-temperature episodes (hyperthermals) sometime between the latest Palaeocene establishment of intercontinental land connections and the presence of giant formiciines in Europe and North America by the early middle Eocene.
Publisher: Society for Sedimentary Geology
Date: 10-2005
Publisher: Society for Sedimentary Geology
Date: 10-2005
Publisher: Elsevier BV
Date: 10-2015
Publisher: PANGAEA - Data Publisher for Earth & Environmental Science
Date: 2021
Publisher: Canadian Science Publishing
Date: 06-2016
Abstract: Western North America preserves a rich record of Eocene life and environments under globally warm climates, and represents an interval where significant coal and other minerals were deposited. The Eocene is of interest to biologists and paleontologists for its record of the appearance and rise to dominance of many plant, insect, and mammal groups now typical of the temperate forests of North America, admixed with groups now well represented in tropical areas or restricted to eastern Asia. This record is also of interest for its potential contribution to our understanding of interactions between climate, the biota, and the ecosystems they occupied, under atmospheric carbon dioxide levels much higher than today. Documentation of the Eocene in western North America offers insights into the effects of future greenhouse climates. A special symposium held at the 2014 Annual Meeting of the Geological Society of America in Vancouver, British Columbia, brought together geologists, paleontologists, and biologists with an interest in these questions. This paper introduces the special issue that includes a selection of papers drawn from that symposium as well as on related topics, spanning the Early to Late Eocene, and geographically from British Columbia to Colorado.
Publisher: Elsevier BV
Date: 05-2013
Publisher: Canadian Science Publishing
Date: 09-1993
DOI: 10.1139/E93-169
Abstract: A record of polar Eocene forests is preserved as in situ tree-stump fields and leaf-litter mats in Buchanan Lake Formation sediments on Axel Heiberg Island, in the Canadian Arctic Archipelago. Stratigraphic examination at the centimetre to metre scale of peat–coal lithology and macrofossil floristics in two levels of these fossil forests reflects small-scale changes in forest composition and sw hydrology horizontally and temporal variation vertically. Root system structure and tree base stratigraphy suggest that exposed tree stumps may not include only coeval in iduals of a single forest stand, but rather also in iduals representing different phases of the forest through one cycle of the hydrological development of this Eocene polar forest community. Earlier calculations of stand density and biomass, based upon the assumption that all stumps represent coeval trees, may therefore be greatly overestimated. A mosaic of Alnus – fern bog, mixed coniferous community, and taxodiaceous (Metasequoia–Glyptostrobus) sw appears to have produced both the leaf mats and the in situ stumps, with the taxodiaceous sw the dominant peat-accumulating phase.
Publisher: Pensoft Publishers
Date: 08-03-2013
Publisher: Cambridge University Press (CUP)
Date: 2010
DOI: 10.1666/09021.1
Abstract: In the modern world, biotic ersity is typically higher in low-latitude tropical regions where there is abundant insolation (light and heat) and low thermal seasonality. Because these factors broadly covary with latitude, separating their possible effects on species ersity is difficult. The Eocene was a much more equable world, however, with low temperature seasonality extending into lower-insolation higher, cooler latitudes, allowing us to test these factors by comparing insect species ersity in (1) modern, temperate, low-insolation, highly seasonal Harvard Forest, Massachusetts, U.S.A., 42°29'N (2) modern, tropical, high-insolation, low-seasonality La Selva, Costa Rica, 10°26'N, and (3) Eocene, temperate, low-insolation, yet low-seasonality McAbee, British Columbia, Canada, above 50°N paleolatitude. We found insect ersity at McAbee to be more similar to La Selva than to Harvard Forest, with high species richness of most groups and decreased ersity of ichneumon wasps, indicating that seasonality is key to the latitudinal ersity gradient. Further, midlatitude Eocene woody dicot ersities at McAbee, Republic (Washington, U.S.A.), and Laguna del Hunco (Argentina) are also high, similar to modern tropical s les, higher than at the modern midlatitude Harvard Forest. Modern correlations between latitude, species ersity, and seasonal climates were established some time after the Eocene.
Publisher: Elsevier BV
Date: 09-2020
Publisher: Elsevier BV
Date: 07-2010
Publisher: Copernicus GmbH
Date: 11-01-2018
Publisher: Elsevier BV
Date: 04-1992
Publisher: CSIRO Publishing
Date: 1996
DOI: 10.1071/SB9960095
Abstract: The Australian Tertiary plant fossil record documents rainforests of a tropical to temperate character in south-eastern and south-western Australia for much of the Early Tertiary, and also shows the climatically mediated contraction of these rainforests in the mid to Late Tertiary. The fossil record of Australian monsoon forests, that is semi-evergreen to deciduous vine forests and woodlands of the wet-dry tropics, however, is poorly known. Phytogeographic analyses have suggested an immigrant origin for some floral elements of present day monsoon forests in northern Australia, while other elements appear to have a common history with the tropical rainforests sensu stricto and/or the sclerophyllous flora. Early Tertiary macrofloras in northern South Australia may provide some insight into the origins of Australian tropical monsoon forests. The Middle Eocene macrofloras of the Poole Creek palaeochannel, and the ?Eocene-Oligocene silcrete macrofloras of Stuart Creek, both in the vicinity of modern Lake Eyre South, have foliar physiognomic characteristics which distinguish them from both modern rainforest and Eocene-Oligocene floras from south-eastern Australia. Preliminary systematic work on these floras suggests the presence of: (1) elements not associated today with monsoon forests (principally 'rainforest' elements, e.g. Gymnostoma, cf. Lophostemon, cf. Athertonia, Podocarpaceae, ?Cunoniaceae) (2) elements typical of both monsoon forests and other tropical plant communities (e.g. cf. Eucalyptus, cf. Syzygium, and Elaeocarpaceae) (3) elements likely to be reflecting sclerophyllous communities (e.g. cf. Eucalyptus, Banksieae and other Proteaceae) and (4) elements more typically associated with, but not restricted to, monsoon forests (e.g. Brachychiton). The foliar physiognomic and floristic evidence is interpreted as indicating a mosaic of gallery or riverine rainforests, and interfluve sclerophyllous plant communities near Lake Eyre in the Early Tertiary deciduous forest components are not clearly indicated. Palaeoclimatic analysis of the Eocene Poole Creek floras suggests that rainfall was seasonal in the Lake Eyre area in the Eocene however, whether this seasonality reflects a monsoonal airflow is not clear.
Publisher: Canadian Science Publishing
Date: 08-2018
Abstract: The lower Eocene McAbee fossil beds (∼53 Ma), in south-central British Columbia, Canada, represent a lacustrine sequence deposited during a time of pervasive regional volcanism. Previous studies on fossil assemblages at the McAbee fossil beds consist of amalgamated collections of plants from several disjunct and stratigraphically unconstrained exposures and horizons, with limited knowledge of the spatio-temporal variation in depositional and taphonomic setting. This study presents a high-resolution lithostratigraphic analysis of the McAbee main site to provide stratigraphic, paleoenvironmental, and taphonomic context to fossil collections. A lithostratigraphic framework was developed for the McAbee main site by correlating tuff marker beds. The sequence was ided into eight lithostratigraphic units on the basis of systematic lithologic trends, a result of varying degrees of volcanic influences. An absence of shallow water indicators, bioturbation, and evidence for fluvio–deltaic influence, and the nonrestricted presence of highly abundant and erse well-preserved plant fossils indicates a deep water, yet relatively near shore facies, suggesting steep sided lake margins. This taphonomic regime imparts minimal transport- and degradation-induced biases in fossil plant assemblages and suggests plant fossils represent local vegetation growing near the point of deposition. The new lithostratigraphic framework coupled with a refined understanding of depositional setting and taphonomic regime demonstrates the opportunity to document conditions of forest ecology within a dynamic volcanic environment over millennial and multi-millennial time scales.
Publisher: University of New Brunswick Libraries - UNB
Date: 20-04-2017
DOI: 10.12789/GEOCANJ.2017.44.116
Abstract: This short summary presents selected results of an ongoing investigation into the feedbacks that contribute to lified Arctic warming. The consequences of warming for Arctic bio ersity and landscape response to global warmth are currently being interpreted. Arctic North American records of large-scale landscape and paleoenvironmental change during the Pliocene are exquisitely preserved and locked in permafrost, providing an opportunity for paleoenvironmental and faunal reconstruction with unprecedented quality and resolution. During a period of mean global temperatures only ~2.5°C above modern, the Pliocene molecular, isotopic, tree-ring, paleofaunal, and paleofloral records indicate that the high Arctic mean annual temperature was 11°C–19°C above modern values, pointing to a much shallower latitudinal temperature gradient than exists today. It appears that the intense Neogene warming caused thawing and weathering to liberate sediment and create a continuous and thick ( .5 km in places) clastic wedge from at least Banks Island to Meighen Island to form a coastal plain that provided a highway for camels and other mammals to migrate and evolve in the high Arctic. In this summary we highlight the opportunities that exist for research on these and related topics with the PoLAR-FIT community.RÉSUMÉCe bref résumé présente les résultats choisis d'une enquête en cours sur les déclencheurs qui contribuent à l’ lification du réchauffement de l'Arctique. Les conséquences du réchauffement sur la bio ersité arctique et de la réponse du paysage au réchauffement climatique sont en cours d’être interprété. Des dossiers nord-américains de paysage à grande échelle et le changement paléoenvironnementales durant le Pliocène sont exceptionnellement préservés et scellées dans un état de congélation qui fournissant une occasion pour la reconstruction paléoenvironnementale et faunistique avec une qualité et une résolution sans précédent. Pendent une période de réchauffement global seulement ~2,5°C au-dessus de moderne les dossiers, moléculaire, isotopique, annaux de croissance, paléofaunistique et paléovégétation indiquent que l'Arctique a connu une augmentation de la température annuelle moyenne de 11°C–19°C au-dessus de moderne, en montrant un inferieur gradient de température latitudinal qu'aujourd'hui. Il semble que le réchauffement intense pendent le Néogène a provoqué la décongélation et erosion pour libérer les sédiments et créer une plaine côtière continuel et épaisse ( 2,5 km dans lieux) qui a fourni une route pour les chameaux et autres mammifères pour migrer et évoluer dans l’Haut-Arctique. Dans ce résumé, nous soulignons les opportunités qui existent pour la recherche sur ces sujets et les sujets connexes avec la communauté PoLAR-FIT.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 16-04-1993
Publisher: University of Chicago Press
Date: 11-2021
DOI: 10.1086/715633
Publisher: Copernicus GmbH
Date: 15-02-2019
Publisher: Springer Science and Business Media LLC
Date: 08-2012
DOI: 10.1038/NATURE11300
Abstract: The warmest global climates of the past 65 million years occurred during the early Eocene epoch (about 55 to 48 million years ago), when the Equator-to-pole temperature gradients were much smaller than today and atmospheric carbon dioxide levels were in excess of one thousand parts per million by volume. Recently the early Eocene has received considerable interest because it may provide insight into the response of Earth's climate and biosphere to the high atmospheric carbon dioxide levels that are expected in the near future as a consequence of unabated anthropogenic carbon emissions. Climatic conditions of the early Eocene 'greenhouse world', however, are poorly constrained in critical regions, particularly Antarctica. Here we present a well-dated record of early Eocene climate on Antarctica from an ocean sediment core recovered off the Wilkes Land coast of East Antarctica. The information from biotic climate proxies (pollen and spores) and independent organic geochemical climate proxies (indices based on branched tetraether lipids) yields quantitative, seasonal temperature reconstructions for the early Eocene greenhouse world on Antarctica. We show that the climate in lowland settings along the Wilkes Land coast (at a palaeolatitude of about 70° south) supported the growth of highly erse, near-tropical forests characterized by mesothermal to megathermal floral elements including palms and Bombacoideae. Notably, winters were extremely mild (warmer than 10 °C) and essentially frost-free despite polar darkness, which provides a critical new constraint for the validation of climate models and for understanding the response of high-latitude terrestrial ecosystems to increased carbon dioxide forcing.
Publisher: Canadian Science Publishing
Date: 02-2005
DOI: 10.1139/E05-013
Abstract: We dedicate this issue to the memory of Wesley C. Wehr, former Affiliate Curator of Paleobotany, Burke Museum of Natural History and Culture, Seattle, Washington. Wes' contributions to paleontology, particularly in the Okanagan Highlands of Washington State and British Columbia his influence on a generation of paleontologists (particularly paleobotanists) working in and coming from this region and his warm friendship that brought together members of the scientific and arts communities were deeply influential, and will be fondly remembered.
Publisher: Canadian Science Publishing
Date: 02-2005
DOI: 10.1139/E05-012
Abstract: Climate change is a matter of concern to society, decision makers, and scientists. As part of the debate about the science of climate change, and in particular the extent to which current climate change is due to human activity or part of the natural variability of the global climate system, earth scientists try to understand how climates have changed in the past, and how past warming and cooling episodes affected the landscape and the plants and animals that occupied that landscape. It is also clear from the fossil record that past climate change has played a role in the evolution of animal and plant lineages, as well as plant and animal communities. Preserved in a series of lake deposits across northeastern Washington State, USA., to Smithers in north-central British Columbia, Canada, the Okanagan Highlands fossil deposits preserve a record of a time when the world was much warmer than now because of a naturally enhanced greenhouse effect, and the poles were ice-free and supported great forests. These sites are well known to fossil collectors for their beautifully preserved insects, fish, and plants. The Okanagan Highlands were an upland 50 million years ago, during the Early Eocene, and supported erse forests swarming with insects and other animals that today are found in both temperate and tropical areas. The trees, shrubs, and herbs of these Eocene forests echo this pattern, including palms and bald cypress, together with spruce and birches. This special issue presents a series of papers that resulted from a symposium held in 2003 on the Okanagan Highlands that details the warm Eocene world of the interior uplands of northeastern Washington and British Columbia. Topics include reconstructing the landscape, biogeography, palaeoclimates, and fossil plants, insects, diatoms, and fish.
Publisher: The Royal Society
Date: 28-08-1993
Abstract: There are many methods for inferring terrestrial palaeoclimates from palaeontological data, including the size and species ersity of ectothermic vertebrates, the locomotor and dental adaptations of mammals, characteristics of leaf shape, size, and epidermis, wood anatomy, and the climatic preferences of nearest living relatives of fossil taxa. Estimates of palaeotem perature have also been based on stable oxygen isotope ratios in shells and bones. Interpretation of any of these data relies in some way on uniformitarian assumptions, although at different levels depending on the method. Most of these methods can be applied to a palaeoclimatic reconstruction for the interior of North America during the early Eocene, which is thought to be the warmest interval of global climate in the Cenozoic. Most of the data indicate warm equable climates with little frost. Rainfall was variable, but strong aridity was local or absent. The inferred palaeoclimate is very different from the present climate of the region and from model simulations for the Eocene. This suggests that models fail to incorporate forcing factors that were present at that time, that they treat the heat regime of continents unrealistically, and/or that model inputs such as sea surface temperature gradients or palaeotopography are incorrect.
Publisher: Copernicus GmbH
Date: 22-10-2014
Abstract: Abstract. The Paleocene-Eocene thermal maximum (PETM) represents a ~170 kyr episode of anomalous global warmth ~56 Ma ago. The PETM is associated with rapid and massive injections of 13C-depleted carbon into the ocean-atmosphere system reflected as a prominent negative carbon isotope excursion (CIE) in sedimentary components. Earth's surface and deep ocean waters warmed by ~5 °C, of which part may have occurred prior to the CIE. However, few records document continental climatic trends and changes in seasonality have not been documented. Here we present the first high-resolution vegetation reconstructions for the PETM, based on bioclimatic analysis of terrestrially-derived spore and pollen assemblages preserved in an expanded section from the Central North Sea. Our data indicate reductions in boreal conifers and an increase in mesothermal to megathermal taxa, reflecting a shift towards wetter and warmer climate. We also record an increase in summer temperatures, greater in magnitude than the rise in mean annual temperature changes. Within the CIE, vegetation varies significantly with initial increases in epiphytic and climbing ferns, and development of extensive wetlands, followed by abundance of Carya spp. indicative of broadleaf forest colonization. Critically, the change in vegetation we report occurs prior to the CIE, and is concomitant with anomalous marine ecological change, as represented by the occurrence of Apectodinium augustum. This suggests that lifications of seasonal extremes triggered carbon injection.
Publisher: Copernicus GmbH
Date: 04-08-2020
Abstract: Abstract. Early Eocene climates were globally warm, with ice-free conditions at both poles. Early Eocene polar landmasses supported extensive forest ecosystems of a primarily temperate biota but also with abundant thermophilic elements, such as crocodilians, and mesothermic taxodioid conifers and angiosperms. The globally warm early Eocene was punctuated by geologically brief hyperthermals such as the Paleocene–Eocene Thermal Maximum (PETM), culminating in the Early Eocene Climatic Optimum (EECO), during which the range of thermophilic plants such as palms extended into the Arctic. Climate models have struggled to reproduce early Eocene Arctic warm winters and high precipitation, with models invoking a variety of mechanisms, from atmospheric CO2 levels that are unsupported by proxy evidence to the role of an enhanced hydrological cycle, to reproduce winters that experienced no direct solar energy input yet remained wet and above freezing. Here, we provide new estimates of climate and compile existing paleobotanical proxy data for upland and lowland midlatitude sites in British Columbia, Canada, and northern Washington, USA, and from high-latitude lowland sites in Alaska and the Canadian Arctic to compare climatic regimes between the middle and high latitudes of the early Eocene – spanning the PETM to the EECO – in the northern half of North America. In addition, these data are used to reevaluate the latitudinal temperature gradient in North America during the early Eocene and to provide refined biome interpretations of these ancient forests based on climate and physiognomic data.
Publisher: Geological Society of America
Date: 25-08-2020
DOI: 10.1130/G47343.1
Abstract: Current knowledge of terrestrial ecosystem response to the Paleocene-Eocene Thermal Maximum (PETM ca. 56 Ma) is largely based on the midlatitudes of the Northern Hemisphere. To more fully reconstruct global terrestrial ecosystem response to the PETM, we generated vegetation and biomarker proxy records from an outcrop section on the southern coast of Australia (∼60°S paleolatitude). We documented a rapid, massive, and sustained vegetation turnover as a response to regional PETM warming of ∼1–4 °C, abruptly transitioning from a warm temperate to a meso-megathermal rain forest similar to that of present-day northeastern Queensland, Australia. The onset of this vegetation change preceded the characteristic PETM carbon-isotope excursion (CIE) by several thousand years. The reconstructed ecosystem change is much stronger than in other Southern Hemisphere records, highlighting the need for consideration of regional paleoceanographic, paleogeographic, and biogeographic characteristics to fully understand the global terrestrial ecosystem response to PETM climate forcing.
Publisher: Elsevier BV
Date: 11-2009
Publisher: Wiley
Date: 06-2013
DOI: 10.12705/623.15
Publisher: Schweizerbart
Date: 12-12-2019
Publisher: Copernicus GmbH
Date: 24-03-2020
DOI: 10.5194/CP-2020-32
Abstract: Abstract. Early Eocene climates were globally warm, with ice-free conditions at both poles. Early Eocene polar landmasses supported extensive forest ecosystems of a primarily temperate biota, but also with abundant thermophilic elements such as crocodilians, and mesothermic taxodioid conifers and angiosperms. The globally warm early Eocene was punctuated by geologically brief hyperthermals such as the Paleocene-Eocene Thermal Maximum (PETM), culminating in the Early Eocene Climatic Optimum (EECO), during which the range of thermophilic plants such as palms extended into the Arctic. Climate models have struggled to reproduce early Eocene Arctic warm winters and high precipitation, with models invoking a variety of mechanisms, from atmospheric CO2 levels that are unsupported by proxy evidence, to the role of an enhanced hydrological cycle to reproduce winters that experienced no direct solar energy input yet remained wet and above freezing. Here, we provide new estimates of climate, and compile existing paleobotanical proxy data for upland and lowland mid-latitudes sites in British Columbia, Canada, and northern Washington, USA, and from high-latitude lowland sites in Alaska and the Canadian Arctic to compare climatic regimes between mid- and high latitudes of the early Eocene – spanning the PETM to the EECO – of the northern half of North America. In addition, these data are used to reevaluate the latitudinal temperate gradient in North America during the early Eocene, and to provide refined biome interpretations of these ancient forests based on climate and physiognomic data.
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/SB97028
Abstract: Silicified leaf impressions attributed to the tribe Banksieae (Proteaceae) are reported from a new Tertiary macroflora from near Glen Helen, Northern Territory and from the Miocene Stuart Creek macroflora, northern South Australia. The fossil leaf material is described and placed in Banksieaeformis Hill & Christophel. Banksieaeformis serratus sp. nov. is very similar in gross morphology to the extant Banksia baueri R.Br. and B. serrata L.f. and is therefore representative of a leaf type in Banksia that is widespread geographically and climatically within Australia and that is unknown in Dryandra or other genera of the Banksieae. The leaf material from Stuart Creek and Woomera represents the lobed leaf form typical of Paleogene macrofloras from southern Australia, but one species,B. langii sp. nov., is closely similar in gross form to Banksieaephyllum taylorii R.J.Carpenter, G.J.Jordan & R.S.Hill et al. from the Late Paleocene of New South Wales and similarly may be sclerophyllous. Also reported are impressions of Banksia infructescences, or ‘seed cones’, in Neogene sediments near Marree and Woomera, South Australia. These fossils demonstrate the presence of Banksiinae in central Australia in the mid-Tertiary, potentially indicating the former existence of linking corridors between now widely separated populations of Banksia.
Location: Australia
Start Date: 1998
End Date: 2000
Funder: Australian Research Council
View Funded ActivityStart Date: 2015
End Date: 2016
Funder: National Geographic Society
View Funded ActivityStart Date: 1992
End Date: 1993
Funder: Smithsonian Institution
View Funded ActivityStart Date: 1990
End Date: 1992
Funder: Natural Sciences and Engineering Research Council of Canada
View Funded ActivityStart Date: 2005
End Date: 2024
Funder: Canada Foundation for Innovation
View Funded ActivityStart Date: 2013
End Date: 2024
Funder: Canada Foundation for Innovation
View Funded ActivityStart Date: 2016
End Date: 2018
Funder: Natural Sciences and Engineering Research Council
View Funded ActivityStart Date: 2018
End Date: 2019
Funder: Brandon University
View Funded ActivityStart Date: 2020
End Date: 2023
Funder: Brandon University
View Funded ActivityStart Date: 2017
End Date: 2018
Funder: Brandon University
View Funded Activity