Contrasts between the Climatic Ranges of Fossil and Extant Taxa: Causes and Consequences for Palaeoclimatic Estimates

1997 ◽  
Vol 45 (3) ◽  
pp. 465 ◽  
Author(s):  
Gregory J. Jordan
Keyword(s):  
Climate Reconstruction ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Warm Climate ◽  
Extinct Species ◽  
Fossil Assemblage ◽  
The Past

Many palaeoclimate estimates are based on the climatic ranges of the nearest living relatives (NLRs) of fossils. If the climatic ranges of the true NLRs of the taxa in a fossil assemblage do not overlap, then the past climatic ranges of some of the fossil taxa are different from the ranges of their NLRs. Discrepancies between the climatic ranges of the inferred NLRs of co-occurring fossils are common, particularly in assemblages older than the Middle Pleistocene. Evidence from Early Pleistocene Tasmania indicates that many anomalies are caused by extinct species, or at least extinct genotypes. It is likely that pre-Quaternary fossil deposits will contain more extinct taxa. Most of the extinct Early Pleistocene taxa have warm climate NLRs, but they appear to have occurred in climates no warmer than modern climates in western Tasmania. Sometimes NLR approaches in climate reconstruction appear to be biased by extinctions of ecotypes and species, especially ones caused by the Pleistocene glacial–interglacial cycles. Extinctions also mean that it is difficult to identify palaeoclimates that are different from any modern climate.

Lower–Middle Pleistocene Stratigraphy of the Southern West Siberian Plain: New Data

2021 ◽  
Vol 62 (12) ◽  
pp. 1359-1372
Author(s):  
V.S. Zykin ◽  
V.S. Zykina ◽  
D.G. Malikov ◽  
L.G. Smolyaninova ◽  
O.B. Kuzmina
Keyword(s):  
West Siberia ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Northern Eurasia ◽  
West Siberian Plain ◽  
Warm Climate ◽  
Faunal Assemblages ◽  
Quaternary Stratigraphy ◽  
Stable Part ◽  
Irtysh River

Abstract —The Quaternary stratigraphy of the southern West Siberian Plain is considered in the context of the updated International Chronostratigraphic Scale, with the Neogene/Quarternary boundary at 2.588 Ma. New geological, lithological, paleontological, and paleomagnetic data from a reference Quaternary section in the Irtysh River valley near Isakovka Village provide more rigorous constraints on the Lower–Middle Pleistocene stratigraphy and the respective deposition conditions. The Isakovka outcrop exposes two stratigraphically expressed and paleontologically characterized units that were deposited during regional Pleistocene interglacial events of different ages: the Strunino and Serebryanoe alluvium beds lying over eroded surfaces. The species of the Corbicula genus coexisting with numerous species of Palearctic molluscs, small mammals Allophaiomys deucalion, Mimomys reidi, and last rooted lagurids Borsodia found in the Strunino alluvium are known also from continental equivalents of the warm upper Gelasian Stage in different parts of northern Eurasia. Judging by the presence of extant corbicules, the Strunino alluvium was deposited in a warm climate, with a mean annual air temperature above +16 °C and a mean winter temperature no colder than –8 °C, in rivers that remained free from ice all year round. On the basis of fauna constraints for the Serebryanoe alluvium, along with the first appearance of the European Pisidium clessini molluscs in West Siberia, the unit can be correlated with one of the earliest Middle Pleistocene interglacial events. The faunal assemblages and spore-pollen patterns of the two units indicate that the climate during the Serebryanoe deposition was slightly cooler and wetter than during the Strunino deposition, though steppe landscapes predominated on watersheds in both events. The two alluvial beds, which are traceable in river bluffs, at 30 m above the modern water level in a tectonically stable part of West Siberia, mark the hypsometrically higher position of the river network during the Early Pleistocene and early Middle Pleistocene interglacials.

Increased sea-level sensitivity to CO2 forcing across the Middle Pleistocene Transition from ice-albedo and ice-volume nonlinearities

2021 ◽  
pp. 1
Author(s):  
Parker Liautaud ◽  
Peter Huybers
Keyword(s):  
Sea Level ◽  
Late Pleistocene ◽  
Radiative Forcing ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Early Pleistocene ◽  
Balance Model ◽  
Middle Pleistocene ◽  
Model Parameters ◽  
The Past

AbstractProxy reconstructions indicate that sea level responded more sensitively to CO2 radiative forcing in the late Pleistocene than in the early Pleistocene, a transition that was proposed to arise from changes in ice-sheet dynamics. In this study we analyse the links between sea level, orbital variations, and CO2 using an energy-balance model having a simple ice sheet. Model parameters, including for age models, are inferred over the late Pleistocene using a hierarchical Bayesian method, and the inferred relationships are used to evaluate CO2 levels over the past 2 My in relation to sea level. Early-Pleistocene model CO2 averages 246 ppm (244 ppm - 249 ppm 95% c.i.) across 2-1 Ma and indicates that sea level was less sensitive to radiative forcing than in the late Pleistocene, consistent with foregoing δ11B-derived estimates. Weaker early-Pleistocene sea-level sensitivity originates from a weaker ice-albedo feedback and the fact that smaller ice sheets are thinner, absent changes over time in model equations or parameters. An alternative scenario involving thin and expansive early-Pleistocene ice sheets, in accord with some lines of geologic evidence, implies 15 ppm lower average CO2 or ~10-15 m higher average sea level during the early Pleistocene relative to the original scenario. Our results do not rule out dynamical transitions during the middle Pleistocene, but indicate that variations in the sea-level response to CO2 forcing over the past 2 My can be explained on the basis of nonlinearities associated with ice-albedo feedbacks and ice-sheet geometry that are consistently present across this interval.

scholarly journals The biome reconstruction approach as a tool for interpretation of past vegetation and climate changes: application to modern and fossil pollen data from Lake El'gygytgyn, Far East Russian Arctic

2013 ◽  
Vol 9 (3) ◽  
pp. 3449-3487 ◽  
Author(s):  
P. E. Tarasov ◽  
A. A. Andreev ◽  
P. M. Anderson ◽  
A. V. Lozhkin ◽  
E. Haltia ◽  
...  
Keyword(s):  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Fossil Pollen ◽  
Pollen Data ◽  
Northern Asia ◽  
Study Region ◽  
Late Pliocene ◽  
The Past ◽  
Lake El’Gygytgyn ◽  
Vegetation And Climate

Abstract. The modern and fossil pollen data obtained under the framework of the multi-disciplinary international "El'gygytgyn Drilling Project" represent a unique archive that allows the testing of a range of pollen-based reconstruction approaches and the deciphering of changes in the regional vegetation and climate since ~3.58 Ma. In the current study we provide details of the biome reconstruction method applied to the late Pliocene and Quaternary pollen records from Lake El'gygytgyn. All terrestrial pollen taxa identified in the spectra from Lake El'gygytgyn were assigned to major vegetation types (biomes), which today occur near the lake and in the broader region of eastern and northern Asia and, thus, could potentially have been present in this region during the past. When applied to the modern surface pollen spectra from the lake, the method shows a dominance of the tundra biome that currently characterizes the Lake El'gygytgyn area. When applied to the pollen spectra from the middle Pleistocene to present, the method suggests (1) a predominance of tundra during the Holocene, (2) a short interval during the marine isotope stage (MIS) 5.5 interglacial distinguished by cold deciduous forest, and (3) a long phase of taiga dominance during MIS 31 and, particularly, MIS 11.3. These two latter interglacials seem to be some of the longest and warmest intervals within the past million years. During the late Pliocene–early Pleistocene interval (i.e., ~3.562–2.200 Ma), there is good correspondence between the millennial-scale vegetation changes documented in the Lake El'gygytgyn record and the alternation of cold and warm marine isotope stages, which reflect changes in the global ice volume and sea level. The biome reconstruction demonstrates changes in the regional vegetation which suggest a step-like transition from generally warmer/wetter environments of the earlier (i.e., Pliocene) interval towards colder/drier environments of the Pleistocene. The reconstruction of most of the species-rich cool mixed and cool conifer forest biomes is particularly noticeable prior to MIS G16, whereas tundra becomes a prominent feature after MIS G6. These results consistently indicate that the study region supported significant tree populations during most of the interval prior to ~2.730 Ma. The biomization results also suggest that the transition from mostly forested to mostly open landscape was not gradual, but rather occurred in step-like fashion. Thus, the cold and drought tolerant steppe biome first appears in the reconstruction ca. 3.298 Ma during the tundra dominated MIS M2, whereas the tundra biome initially occurs between ~3.379 and ~3.378 Ma within MIS MG4. Prior to ~2.800 Ma, several other cold stages during this generally warm Pliocene interval experienced a dominance of tundra and a great reduction of tree populations in the regional vegetation.

Warm climate under high CO2 level in the early Pleistocene based on a leaf fossil assemblage in central Japan

2018 ◽  
Vol 258 ◽  
pp. 146-153 ◽  
Author(s):  
Yuqing Wang ◽  
Arata Momohara ◽  
Ayano Ito ◽  
Tohru Fukushima ◽  
Yong-Jiang Huang
Keyword(s):  
Early Pleistocene ◽  
Warm Climate ◽  
Central Japan ◽  
High Co2 ◽  
Fossil Assemblage ◽  
Co2 Level

scholarly journals A pollen-based biome reconstruction over the last 3.562 million years in the Far East Russian Arctic – new insights into climate–vegetation relationships at the regional scale

2013 ◽  
Vol 9 (6) ◽  
pp. 2759-2775 ◽  
Author(s):  
P. E. Tarasov ◽  
A. A. Andreev ◽  
P. M. Anderson ◽  
A. V. Lozhkin ◽  
C. Leipe ◽  
...  
Keyword(s):  
Short Interval ◽  
Regional Scale ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Reconstruction Method ◽  
Northern Asia ◽  
Study Region ◽  
Late Pliocene ◽  
The Past ◽  
Lake El’Gygytgyn

Abstract. The recent and fossil pollen data obtained under the frame of the multi-disciplinary international El'gygytgyn Drilling Project represent a unique archive, which allows the testing of a range of pollen-based reconstruction approaches and the deciphering of changes in the regional vegetation and climate. In the current study we provide details of the biome reconstruction method applied to the late Pliocene and Quaternary pollen records from Lake El'gygytgyn. All terrestrial pollen taxa identified in the spectra from Lake El'gygytgyn were assigned to major vegetation types (biomes), which today occur near the lake and in the broader region of eastern and northern Asia and, thus, could be potentially present in this region during the past. When applied to the pollen spectra from the middle Pleistocene to present, the method suggests (1) a predominance of tundra during the Holocene, (2) a short interval during the marine isotope stage (MIS) 5.5 interglacial distinguished by cold deciduous forest, and (3) long phases of taiga dominance during MIS 31 and, particularly, MIS 11.3. These two latter interglacials seem to be some of the longest and warmest intervals in the study region within the past million years. During the late Pliocene–early Pleistocene interval (i.e., ~3.562–2.200 Ma), there is good correspondence between the millennial-scale vegetation changes documented in the Lake El'gygytgyn record and the alternation of cold and warm marine isotope stages, which reflect changes in the global ice volume and sea level. The biome reconstruction demonstrates changes in the regional vegetation from generally warmer/wetter environments of the earlier (i.e., Pliocene) interval towards colder/drier environments of the Pleistocene. The reconstruction indicates that the taxon-rich cool mixed and cool conifer forest biomes are mostly characteristic of the time prior to MIS G16, whereas the tundra biome becomes a prominent feature starting from MIS G6. These results consistently indicate that the study region supported significant tree populations during most of the interval prior to ~2.730 Ma. The cold- and drought-tolerant steppe biome first appears in the reconstruction ~3.298 Ma during the tundra-dominated MIS M2, whereas the tundra biome initially occurs between ~3.379 and ~3.378 Ma within MIS MG4. Prior to ~2.800 Ma, several other cold stages during this generally warm Pliocene interval were characterized by the tundra biome.

Two new Banksia species from pleistocene sediments in western Tasmania

1991 ◽  
Vol 4 (3) ◽  
pp. 499 ◽  
Author(s):  
GI Jordan ◽  
RS Hill
Keyword(s):  
Plant Species ◽  
Late Pleistocene ◽  
Environmental Changes ◽  
Middle Pleistocene ◽  
Extinct Species ◽  
The Third ◽  
Taxonomic Groups

Subtribe Banksiinae of the Proteaceae was diverse in Tasmania in the early and middle Tertiary, but is now restricted to two species, Banksia marginata and B. serrata. Rapid and extreme environmental changes during the Pleistocene are likely causes of the extinction of some Banksia species in Tasmania. Such extinctions may have been common in many taxonomic groups. The leaves and infructescences of Banksia kingii Jordan & Hill, sp. nov. are described from late Pleistocene sediments. This is the most recent macrofossil record of a now extinct species in Tasmania. Banksia kingii is related to the extant B. saxicola. Banksia strahanensis Jordan & Hill, sp. nov. (known only from a leaf and leaf fragments and related to B. spinulosa) is described from Early to Middle Pleistocene sediments in Tasmania. This represents the third Pleistocene macrofossil record of a plant species which is now extinct in Tasmania.

scholarly journals Topographic and Glaciological Controls on Holocene Ice-Sheet Margin Dynamics. Central West Greenland

1990 ◽  
Vol 14 ◽  
pp. 307-310 ◽  
Author(s):  
C.R. Warren ◽  
N.R.J. Hulton
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Glacial Maximum ◽  
Warm Climate ◽  
Short Term ◽  
The West ◽  
West Greenland ◽  
The Past

The retreat of the West Greenland ice sheet from its Sisimiut (Wisconsinan) glacial maximum, was punctuated by a series of Stillstands or small readvances that formed numerous moraines. These landforms have been interpreted in the past as the result of short-term, regional falls in ablation-season temperatures. However, mapping of the geomorphological evidence south of Ilulissat (Jakobshavn) suggests that retreat behaviour was not primarily governed by climate, and therefore that the former ice margins are not palaeoclimatically significant. During warm climate ice-sheet wastage, the successive quasi-stable positions adopted by the ice margin were largely governed by topography. The retreat of the inherently unstable calving glaciers was arrested only at topographically-determined locations where stability could be achieved.

Aeolian influx and related environmental conditions on Gran Canaria during the early Pleistocene

2018 ◽  
Vol 91 (1) ◽  
pp. 35-50 ◽  
Author(s):  
Inmaculada Menéndez ◽  
José Mangas ◽  
Esperança Tauler ◽  
Vidal Barrón ◽  
José Torrent ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Textural Analysis ◽  
Climatic Conditions ◽  
Saharan Dust ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Quartz Content ◽  
Gran Canaria ◽  
Climatic Oscillations ◽  
Climatic Variations

AbstractThe island of Gran Canaria is regularly affected by dust falls due to its proximity to the Saharan desert. Climatic oscillations may affect the Saharan dust input to the island. Geochemical, mineralogical, and textural analysis was performed on a well-developed and representative early Pleistocene paleosol to examine Saharan dust contribution to Gran Canaria. Significant and variable Saharan dust content was identified in addition to weathering products such as iron oxides and clay minerals. Variations in quartz and iron oxide concentrations in the paleosol likely reflect different Saharan dust input in more/less-contrasted rhexistasic/biostatic climatic conditions. Linking the quartz content in Canarian soils, the Ingenio paleosol, and two Canarian loess-like deposits to different ages from the Quaternary, we hypothesized that the dust input should be lower (about 33–38%) throughout the early to middle Pleistocene than during the late Quaternary. The Saharan dust input to the Gran Canaria profile in the Pleistocene persisted in spite of climatic variations.

scholarly journals Cosmogenic burial dating of in cave-deposited alluvium: unravelling long-term incision rates and complex speleogenesis in multi-level cave systems

2020 ◽  
Author(s):  
Gilles Rixhon ◽  
Didier L. Bourlès ◽  
Régis Braucher ◽  
Alexandre Peeters ◽  
Alain Demoulin
Keyword(s):  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Fluvial Terrace ◽  
Base Level ◽  
Cave System ◽  
River Incision ◽  
Order Of Magnitude ◽  
History Of ◽  
Multi Level

<p>Multi-level cave systems record the history of regional river incision in abandoned alluvium-filled phreatic passages which, mimicking fluvial terrace sequences, represent former phases of fluvial base-level stability. In this respect, cosmogenic burial dating of in cave-deposited alluvium (usually via the nuclide pair <sup>26</sup>Al/<sup>10</sup>Be) represents a suitable method to quantify the pace of long-term river incision. Here, we present a dataset of fifteen <sup>26</sup>Al/<sup>10</sup>Be burial ages measured in fluvial pebbles washed into a multi-level cave system developed in Devonian limestone of the uplifted Ardenne massif (eastern Belgium). The large and well-documented Chawresse system is located along the lower Ourthe valley (i.e. the main Ardennian tributary of the Meuse river) and spans altogether an elevation difference exceeding 120 m.</p><p>The depleted <sup>26</sup>Al/<sup>10</sup>Be ratios measured in four individual caves show two main outcomes. Firstly, computed burial ages ranging from ~0.2 to 3.3 Ma allows highlighting an acceleration by almost one order of magnitude of the incision rates during the first half of the Middle Pleistocene (from ~25 to ~160 m/Ma). Secondly, according to the relative elevation above the present-day floodplain of the sampled material in the Manants cave (<35 m), the four internally-consistent Early Pleistocene burial ages highlight an “anomalous” old speleogenesis in the framework of a gradual base-level lowering. They instead point to intra-karsting reworking of the sampled material in the topographically complex Manants cave. This in turn suggests an independent, long-lasting speleogenetic evolution of this specific cave, which differs from the <em>per descensum</em> model of speleogenesis generally acknowledged for the regional multi-level cave systems and their abandoned phreatic galleries. In addition to its classical use for inferring long-term incision rates, cosmogenic burial dating can thus contribute to better understand specific and complex speleogenetic evolution.</p>

scholarly journals GEOLOGICAL AND MAGNETIC SUSCEPTIBILITY MAPPING OF MOUNT GIOUCHTA (CENTRAL CRETE)

2017 ◽  
Vol 43 (1) ◽  
pp. 289 ◽  
Author(s):  
E. Kokinou ◽  
E. Kamberis ◽  
A. Sarris ◽  
I. Tzanaki
Keyword(s):  
Magnetic Susceptibility ◽  
Spatial Distribution ◽  
Stress Field ◽  
Magnetic Measurements ◽  
Strain Analysis ◽  
Geological Structure ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Western Slope ◽  
Strain Pattern

Giouchta Mt. is located south of Heraklion city, in Crete. It is an N-S trending morphological asymmetric ridge, with steep western slope whilst the eastern slope represents a smoother relief, composed of Mesozoic limestone and Eocene- lower Oligocene flysch sediments of the Gavrovo -Tripolis zone. The present study focuses on the geological structure of Mt. Giouchta. Field mapping and tectonic analysis is performed for this purpose. The dominant structures are contractional in nature, deformed by normal faulting related to the extensional episodes initiated in Serravallian times. The strain pattern in the area is revealed from strain analysis. It is inferred that the orientation of the stress field in the area has changed several times: the N-S, stress field which was dominant during Late Serravallian times changed to NE-SW (in Late Serravallian? - Early Tortonian) and subsequently to WNW-ESE (Early to Middle Tortonian) to become NW-SE in Late Tortonian. This orientation changed also during the Quaternary times trending from NW-SE (Early Pleistocene) to ENE-WSW (Middle Pleistocene-Holocene). In addition to the above, surface soil samples were collected in the wider area of mount Giouchta and they were analyzed in order to determine the magnetic susceptibility. GIS techniques were used for mapping the spatial distribution of the geological features and the magnetic measurements on the topographic relief of the area. Statistical analysis techniques were also applied in order to investigate the relation of faulting and magnetic susceptibility. Maps representing the spatial distribution of the above measurements were created by using appropriate interpolation algorithms.

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