Late Pliocene Pleistocene Research Articles

Parvatrema spp. (Digenea, Gymnophallidae) with parthenogenetic metacercariae: diversity, distribution and host specificity in the palaearctic

There are several species of gymnophallid digeneans in the genus Parvatrema that are unique in developing metacercariae that reproduce by parthenogenesis in the second intermediate host. Transmission of these digeneans takes place in coastal ecosystems of the North Pacific and North Atlantic seas. The first intermediate hosts are bivalves, the second ones are gastropods, and the definitive hosts are migratory birds. We integrated data accumulated over 25 years of research and differentiated a complex of five closely related species. They differ in the molluscan second intermediate hosts, distribution ranges, and life cycles patterns. The type I life cycle includes two generations of parthenogenetic metacercariae, followed by development of metacercariae which are invasive for the definitive host. In the type II life cycle, the number of generations of parthenogenetic metacercariae is unlimited, and they can also produce cercariae. These cercariae emerge into the environment and can infect new individuals of the second intermediate host. We conclude that the type I life cycle is a derived option that has evolved as a better fit to transmission in the unstable conditions in the intertidal zone. Another evolutionary trend in Parvatrema is transition from inhabiting the extrapallial space of the gastropod second intermediate host to endoparasitism in its mantle and internal organs. rDNA sequence analysis highlighted that Parvatrema spp. with parthenogenetic metacercariae form a monophyletic clade and suggested the Pacific origin of the group, with two transfers to the North Atlantic and colonisation of new second intermediate host species. Apparently the group formed in the late Pliocene-Pleistocene and diversified as a result of recurrent isolation in inshore refugia during glacial periods. We argue that parthenogenetic metacercariae in Parvatrema may serve as a model for early digenean evolution, demonstrating the first steps of adopting the molluscan first intermediate host and becoming tissue parasites.

Controlling influence of water and ice on eruptive style and edifice construction in the Mount Melbourne Volcanic Field (northern Victoria Land, Antarctica)

The Mount Melbourne Volcanic Field (MMVF) is part of the West Antarctic Rift System, one of Earth’s largest intra-continental rift zones. It contains numerous small, compositionally diverse (alkali basalt–benmoreite) flank and satellite vents of Late Miocene–Pliocene age (≤12.50 Ma; mainly less than 2.5 Ma). They demonstrate a wide range of morphologies and eruptive mechanisms despite overlapping compositions and elevations, and they occur in a relatively small area surrounding the active Mount Melbourne stratovolcano. The volcanic outcrops fall into several main categories based on eruptive style: scoria cones, tuff cones, megapillow complexes, and shield volcanoes. Using the analysis of lithofacies and appraisal of the internal architectures of the outcrops, we have interpreted the likely eruptive setting for each center and examined the links between the environmental conditions and the resulting volcanic edifice types. Previous investigations assumed a glacial setting for most of the centers but without giving supporting evidence. We demonstrate that the local contemporary environmental conditions exerted a dominant control on the resulting volcanic edifices (i.e., the presence or absence of water, including ice or snow). The scoria cones erupted under dry subaerial conditions. Products of highly explosive hydrovolcanic eruptions are represented by tuff cones. The water involved was mainly glacial (meltwater) but may have been marine in a few examples, based on a comparison of the contrasting internal architectures of tuff cones erupted in confined (glacial) and unconfined (marine, lacustrine) settings. One of the glaciovolcanic tuff cones ceased activity shortly after it began transitioning to a tuya. The megapillow complexes are highly distinctive and have not been previously recognized in glaciovolcanic successions. They are subglacial effusive sequences emplaced as interconnected megapillows, lobes, and thick simple sheet lavas. They are believed to have erupted at moderately high discharge and reduced cooling rates in partially drained englacial vaults under ice, probably several hundred meters in thickness. Finally, several overlapping small shield volcanoes crop out mainly in the Cape Washington peninsula area. They are constructed of previously unrecognized multiple ‘a‘ā lava-fed deltas, erupted in association with a thin draping ice cover c. 50–145 m thick. Our study highlights how effectively water in all its forms (e.g., snow, ice, and any meltwater) or its absence exerts a fundamental control on eruption dynamics and volcano construction. When linked to published ages and40Ar/39Ar dates produced by this study, the new environmental information indicates that the Late Pliocene–Pleistocene landscape was mainly an icefield rather than a persistent topography-drowning ice sheet. Ice thicknesses also generally increased toward the present.

Dating North Pacific Abyssal Sediments by Geomagnetic Paleointensity: Implications of Magnetization Carriers, Plio-Pleistocene Climate Change, and Benthic Redox Conditions

Non-carbonaceous abyssal fine-grained sediments cover vast parts of the North Pacific’s deep oceanic basins and gain increasing interests as glacial carbon traps. They are, however, difficult to date at an orbital-scale temporal resolution and still rarely used for paleoceanographic reconstructions. Here, we show that sedimentary records of past geomagnetic field intensity have high potential to improve reversal-based magnetostratigraphic age models. Five sediment cores from Central North Pacific mid-latitudes (39–47°N) and abyssal water depths ranging from 3,900 to 6,100 m were cube-sampled at 23 mm resolution and analyzed by automated standard paleo- and rock magnetic methods, XRF scanning, and electron microscopy. Relative Paleointensity (RPI) records were determined by comparing natural vs. anhysteretic remanent magnetization losses during alternating field demagnetization using a slope method within optimized coercivity windows. The paleomagnetic record delivered well interpretable geomagnetic reversal sequences back to 3 Ma. This age span covers the climate-induced transition from a biogenic magnetite prevalence in the Late Pliocene and Early Pleistocene to a dust-dominated detrital magnetic mineral assemblage since the Mid-Pleistocene. Volcaniclastic materials from concurrent eruptions and gravitational or contouritic sediment re-deposition along extinct seamount flanks provide a further important source of fine- to coarse-grained magnetic carriers. Surprisingly, higher proportions of biogenic vs. detrital magnetite in the late Pliocene correlate with systematically lowered RPI values, which seems to be a consequence of magnetofossil oxidation rather than reductive depletion. Our abyssal RPI records match the astronomically tuned stack of the mostly bathyal Pacific RPI records. While a stratigraphic correlation of rock magnetic and element ratio logs with standard oxygen isotope records was sporadically possible, the RPI minima allowed to establish further stratigraphic tie points at ∼50 kyr intervals. Thus, this RPI-enhanced magnetostratigraphy appears to be a major step forward to reliably date unaltered abyssal North Pacific sediments close to orbital-scale resolution.

Cadmium and clay mineral analysis of late Pliocene–Pleistocene deposits from Jianghan Basin, central China: Implications for sedimentary provenance and evolution of the Yangtze River

The Tibetan Plateau uplift, triggered by India–Eurasia collision, is strongly associated with the evolution of the Yangtze River. The evolution of the river is of great significance for understanding the geomorphology of modern Asian landforms and exploring the response of river development to tectonic uplift and monsoon evolution. Although numerous methods have been employed to reconstruct the evolutionary history of the Yangtze River, a century old debate still persists over its age, especially for that of the Three Gorges, the estimated age of which ranges from Late Cretaceous to Late Pleistocene. In this study, provenance of the Late Cenozoic deposits from the Jianghan Basin were determined based on the Cadmium (Cd) and clay mineral contents, to constrain the age of the Three Gorges. Previous studies have reported marked Cd anomalies detected in the Jianghan Basin, Yangtze River system, which were concluded to be dominantly a result of natural factors rather than anthropogenic activities. We identified two units (0–160 m and 160–300 m depth) from samples collected from the Zhoulao (ZL) core, obtained from the depocenter of the Jianghan Basin. The distinctly higher Cd levels from 160 m to the top of the core indicate the input of sediments from above the Three Gorges, especially the Jinsha River catchment. Additionally, three sections were diagnosed on the basis of variations in clay mineral contents and their corresponding formation mechanisms were demonstrated. Sections 1 and 2 derived sediments from proximal materials within the Jianghan Basin and the variations therein were coupled with climatic changes whereas, the sediments in section 3 were found to be prominently controlled by provenance superior to climate change, with materials derived from the upper Yangtze River; these results are consistent with the reported changes in Cd levels. We interpret this change in sediment provenance at 160 m depth resulted from the incision of the Three Gorges, which brought sediments from the Yangtze. The previously obtained paleomagnetic data demonstrate that the boundary at 160 m represents the end of the Olduvai Subchron (1.945–1.778 Ma), meaning that the incision of the Three Gorges valley occurred no later than 1.778 Ma.

<i>Selenogonus narinoensis</i> Stirton, 1947 (Tayassuidae, Cetartiodactyla, Mammalia): taxonomic status and paleobiogeographic implications

Abstract. The species Selenogonus narinoensis was described by Stirton (1947) based on a single specimen which comes from sediments cropping out in the Cocha Verde locality, Nariño Department (Colombia), tentatively referred to the late Pliocene–Pleistocene (MGN 931; IGM p002118, Museo Geológico Nacional, Servicio Geológico Colombiano, Bogotá). However, morphological studies and comparative morphometric observations of the specimen suggest that (1) no diagnostic character supports the validity of the species Selenogonus narinoensis (here considered species inquirenda); (2) a combination of features (e.g., the mandibular condyle located behind the posterior edge of the vertical mandibular ramus, the angular process which projects laterally outwards, a bunolophodont crown morphology, a mesodont crown height, and a simple crown morphology of the third lobe of m3) indicates it belongs to the genus Platygonus; (3) this specimen corresponds to one of the largest South American peccaries; (4) taking into account certain anatomical characters as well as its morphometric range, this specimen is assigned to Platygonus cf. marplatensis. Even though the stratigraphic provenance of the specimen is still doubtful, it can be proposed that (1) it could be one of the most ancient records of tayassuids in South America, as would be expected given its geographical position, and (2) considering the new taxonomic proposal, this specimen represents the first record of Platygonus cf. marplatensis in Colombia and represents one of the northernmost South American records of the genus. This new interpretation would be of great relevance in the Great American Biotic Interchange due to its strategic geographical proximity to the Isthmus of Panama.

Ecological and spatial patterns associated with diversification of South American Physaria (Brassicaceae) through the general concept of species

Analyzing the roles of ecology and geography on speciation and lineage diversification can shed light on the processes that generate and maintain biodiversity. Additionally, lineages rapidly diversifying across unstable habitats provide substantial challenges for resolving evolutionary histories and delimiting species. Physaria is represented in South American by six species distributed from southern Bolivia to northern central Argentina and growing in highlands of the southern-central Andes, but also along the hills and lowlands of central-eastern Argentina. This biogeographical variability, not common among other South American crucifers (Brassicaceae), prompted us to conduct different climatic niche and geographical range comparisons to study the potential roles of ecology and geography through the diversification of the group. However, the remarkable similarity between these species, coupled with the continuous variability of the diagnostic morphological characters, blurs the species boundaries. Therefore, in order to identify independent evolving lineages, we first employed species delimitation methods together with the general lineage concept of species, and used molecular sequences from nuclear ribosomal and chloroplast loci. Secondly, and in the light of the lineages obtained, we explored the roles of geography and ecology on the diversification of South American Physaria and tested for presence of phylogenetic niche-conservatism or niche-divergence patterns, as well as potential ecological speciation. Lineages identified by these delimitation methods were highly congruent with described species; nevertheless, some morphospecies were included under the same independent evolutionary lineage. Our results suggest that the climatic niche divergence along the heterogeneous landscape apparently was a major factor promoting diversification of the South American Physaria. Divergence was registered mainly on the temperature dimension, which promoted shifts between cold-temperate habitats associated with the highlands of the central-southern Andes and warm lowlands from central-eastern Argentina, i.e., the Monte and Dry Chaco ecoregions. In addition, some degree of niche divergence along the precipitation gradient was also secondarily recovered. Allopatry and dispersal capabilities also seem to be associated with the diversification of the group, presumably through the Late Pliocene-Pleistocene, and promoted by glacial cycles and climatic oscillations during the Quaternary. Results of these analyses are also discussed in a general context, which will contribute to the understanding of the evolutionary and ecological patterns of South American Brassicaceae.

Phylogenomics of the Hyalella amphipod species-flock of the Andean Altiplano

Species diversification in ancient lakes has enabled essential insights into evolutionary theory as they embody an evolutionary microcosm compared to continental terrestrial habitats. We have studied the high-altitude amphipods of the Andes Altiplano using mitogenomic, nuclear ribosomal and single-copy nuclear gene sequences obtained from 36 Hyalella genomic libraries, focusing on species of the Lake Titicaca and other water bodies of the Altiplano northern plateau. Results show that early Miocene South American lineages have recently (late Pliocene or early Pleistocene) diversified in the Andes with a striking morphological convergence among lineages. This pattern is consistent with the ecological opportunities (access to unoccupied resources, initial relaxed selection on ecologically-significant traits and low competition) offered by the lacustrine habitats established after the Andean uplift.

Late Pliocene to early Pleistocene climate dynamics in western North America based on a new pollen record from paleo-Lake Idaho

Marked by the expansion of ice sheets in the high latitudes, the intensification of Northern Hemisphere glaciation across the Plio/Pleistocene transition at ~ 2.7 Ma represents a critical interval of late Neogene climate evolution. To date, the characteristics of climate change in North America during that time and its imprint on vegetation has remained poorly constrained because of the lack of continuous, highly resolved terrestrial records. We here assess the vegetation dynamics in northwestern North America during the late Pliocene and early Pleistocene (c. 2.8–2.4 Ma) based on a pollen record from a lacustrine sequence from paleo-Lake Idaho, western Snake River Plain (USA) that has been retrieved within the framework of an International Continental Drilling Program (ICDP) coring campaign. Our data indicate a sensitive response of forest ecosystems to glacial/interglacial variability paced by orbital obliquity across the study interval, and also highlight a distinct expansion of steppic elements that likely occurs during the first strong glacial of the Pleistocene, i.e. Marine Isotope Stage 100. The pollen data document a major forest biome change at ~ 2.6 Ma that is marked by the replacement of conifer-dominated forests by open mixed forests. Quantitative pollen-based climate estimates suggest that this forest reorganisation was associated with an increase in precipitation from the late Pliocene to the early Pleistocene. We attribute this shift to an enhanced moisture transport from the subarctic Pacific Ocean to North America, confirming the hypothesis that ocean-circulation changes were instrumental in the intensification of Northern Hemisphere glaciation.

High‐resolution upper Pliocene to Pleistocene calcareous nannofossil biostratigraphy in Ocean Drilling Program Hole 1146A in the South China Sea

AbstractWe established a high‐resolution calcareous nannofossil biostratigraphy for the late Pliocene–Pleistocene by analyzing a 242 m‐thick, continuous sedimentary succession from Ocean Drilling Program Site 1146, Hole A, in the South China Sea (SCS). A total of 14 calcareous nannofossil datums were detected in the SCS succession. They are, in descending order: first occurrence (FO) of Emiliania huxleyi, last occurrence (LO) of Pseudoemiliania lacunosa, LO of Reticulofenestra asanoi, FO of Gephyrocapsa parallela, FO of R. asanoi, LO of large Gephyrocapsa spp., FO of large G. spp., FO of Gephyrocapsa oceanica, FO of Gephyrocapsa caribbeanica, LO of Calcidiscus macintyrei, LO of Discoaster brouweri, LO of Discoaster pentaradiatus, LO of Discoaster surculus, and LO of Discoaster tamalis. The FO of E. huxleyi was not precisely detected due to poor preservation and dissolution of nannofossils in the underlying strata. We refined the previous calcareous nannofossil biostratigraphy in the SCS by identifying Gephyrocapsa species and four evolutionary extinction events of the genus Discoaster. The proposed calcareous nannofossil biostratigraphy correlates with those reported in other terrestrial and marine areas/sites and global benthic foraminiferal δ18O records. The age–depth curves based on nannofossil biostratigraphy indicate a significant increase in the sedimentation rates at the LO of R. asanoi (0.91–0.85 Ma). The timing of this increase corresponds to reef expansion in the Ryukyu Islands linked to a stepwise increase in Kuroshio Current intensity. This timing is broadly coeval with a sea surface temperature increase of ∼2 °C in the northwestern Pacific due to expansion of the Western Pacific Warm Pool towards the north and south subtropical regions. This can be explained by increased weathering and erosion of terrestrial areas in glacial periods and increased rainfall causing higher sediment transport in interglacial periods, which were both linked to Middle Pleistocene Transition‐related climatic changes.

Akkise-Yalıhüyük (Konya) Arasının Stratigrafisi

In the vicinity of Akkise-Yalıhüyük (south of Konya) region, the Mesozoic sequence of the autochthonous Geyikdağı and the allochthonous Bozkır units is overlain by Neogene-Quaternary Neo- autochthonous cover units with an angular unconformity. Geyikdağı Unit is represented by Late Cretaceous Saytepe formation cosisting of abundant rudist neritic carbonates at the bottom and Campanian-Maastrihtian Alan formation made up of cherty, clayey pelagic limestone and marls at the top. These autochthonous units are overlain by Maastrihtian Hatip ophiolitic melange forming the lower tectonic zone of the allochthonous Bozkır unit. The second allochthonous tectonic unit in the region is represented by Boyalıtepe formation including Late Cretaceous pelagic deposits such as cherty limestone, clayey limestone-marl and radiolarite. The upper allochthonous package of the study area is also represented by the Middle Triassic-Jurassic Gencek formation consisting of medium-thick bedded, abundantly jointed neritic carbonate. The boundaries of autochthonous and allochthonous and Neo-autochthonous rocks in the region are generally faulted. Therefore, the semi-peneplene-peneplene areas of the region are in the form of a depression area. As a result of lacustrine transgression in the Miocene-Early Pliocene period, lacustrine deposition environments were formed in these depression areas. Therefore, today, some lacustrine sediments such as gravelly-sandy-muddy detritics (Sille formation), muddy-clayey carbonates (Ulumuhsine formation) and volcano-sedimentary units (Küçükmuhsine formation) and also dacitic-andesitic volcanics (Erenlerdağı volcanics) are seen in these depression areas. The newest deposits of the study area are the foothill-alluvial fan deposits (Topraklı formation) which were deposited in Late Pliocene-Pleistocene and alluvials in Holocene age.

Facies analysis and depositional setting of the upper pliocene Akchagyl Formation in southeastern Caspian Basin, NE Iran

Pliocene deposits of the Cheleken and Akchagyl Formations constitute the most important hydrocarbon reservoirs in the Caspian Basin of Iran and other adjacent countries. In this study, facies characteristics and depositional setting of these sequences were examined using detailed field observations, petrographical studies, wireline-log and 2D seismic interpretations. Three outcrop sections were measured as the oldest and thickest Paleogene–Neogene units in the southeastern part of the Caspian Sea. Based on macroscopic and microscopic investigations, eleven sedimentary facies were identified in the studied sequence. These facies indicate deposition in alluvial fan, mud-flat, foreshore, shoreface and offshore of a wave-dominated lacustrine environment. The Akchagyl Formation is mainly composed of foreshore and shoreface facies with low gamma-ray values, which grades into offshore facies towards southwestern parts of the basin. The presence of marine biota such as Globigerinoides fistulosus, Ammonia becccarii, Pullenia praecursor, Cardium dombra and nanoplanktons (Discoaster brouweri and Discoaster pentaradiatus) demonstrate that this lacustrine setting was periodically connected to the global oceans, particularly in the Late Pliocene–Pleistocene. The stratigraphic correlation of the studied sections shows significant changes in lithology, facies and thickness of the Pliocene deposits. These changes were controlled by tectonic subsidence and clastic sediment supply during the Early-to-Middle Pliocene along with sea-level fluctuation as a consequence of the Akchagylian transgression episode in the Late Pliocene. Lateral changes in the geological parameters of the Akchagyl deposits indicate a more stable condition within the most part of the study area, especially towards the South Caspian Basin.

Irregular End-Pliocene Discoasters in Sediments of the Southwest Atlantic

Nannofossils were studied, recovered from Late Pliocene–Pleistocene sediments at station 3316 on cruise 46 of the R/V Akademik Ioffe north of the Rio Grande Rise in the Southwest Atlantic. The presence of irregular discoasters in a narrow horizon at the end of the Discoaster brouweri zone of the Upper Pliocene indicates dramatic changes in the living conditions of these organisms, which led to deviations in the regular structure of their skeletons and subsequent extinction at the end of the Pliocene.

Hiatuses in the late Pliocene–Pleistocene stratigraphy of the Ioffe calcareous contourite drift, western South Atlantic

Abstract The Ioffe Drift located in the Antarctic Bottom Water pathway from the Vema Channel to the Brazil Basin provides a suitable site to study past variations in bottom contour currents and their contribution to erosion and accumulation of deep-sea sediments. Our previous study of the reference core AI-2436 from the drift summit (Ivanova et al., 2016a) documented the stratigraphic sequence of the uppermost part of the sedimentary cover ranging from the recent through upper Pliocene, the reduced thickness and/or absence of biostratigraphic zones, and the occurrence of several hiatuses. Here, we provide the multi-proxy biostratigraphic, magnetic susceptibility (MS), color reflectance and X-ray fluorescence (XRF) data in the sediment cores AI-3318 from the summit and AI-3316 from the NE slope of the Ioffe Drift. The new data report numerous long- and short-term stratigraphic gaps over the last ~3 Ma. An interval of specific high-amplitude peaks representing abrupt changes in volume MS and XRF variability is identified from 2.51/2.59 to ~1.9 Ma which can likely serve as a regional stratigraphic benchmark in the future studies of deep-sea contourites. The correlation of three sediment records from the drift suggests that the most pronounced series of hiatuses, associated with enhanced AABW flow intensity occurred from 1.6 to ~0.81 Ma (i.e. roughly, during the Mid-Pleistocene Transition), and from 2.51/2.59 to ~1.9 Ma (i.e. covers the onset of the modern-type deep-water circulation in the South Atlantic (Turnau and Ledbetter (1989)). Comparison of the studied sediment records with DSDP Site 516 reveals reduced thickness of all recovered biostratigraphic zones and more often occurrence of hiatuses in the Ioffe Drift than on the Rio Grande Rise suggesting more vigorous contour currents in the former area.

Late Middle Pleistocene Elephants from Natodomeri, Kenya and the Disappearance of Elephas (Proboscidea, Mammalia) in Africa

Comparative morphometric study of recently recovered fossil elephant molars from Natodomeri, Kenya identifies them as belonging to Elephas jolensis and confirms the presence of this species in Members I and II of the Kibish Formation. Improved datation of these geological units constrains them between 205 and 130 ka. Elephas jolensis is also reported from localities in northern, northwestern, eastern, and southern Africa. Thus, including its Natodomeri occurrence, E. jolensis appears to have been pan-African in distribution. Despite the wide geographic distribution of the species, molars of E. jolensis are remarkably uniform morphometrically. They are characterized by their extreme hypsodonty, high amplitude of enamel folding, high lamellar frequency, and plates that are anteroposteriorly thick relative to transverse valley interval spacing. In addition, they exhibit only a modest number of plates (<20 in M3/m3). Elephas jolensis either evolved from or represents the last stage of Elephas recki, the dominant elephant species in East Africa during the late Pliocene-Pleistocene. The dental morphology and isotopic composition of E. jolensis indicates that, like E. recki, it was a dedicated grazer. In the Kibish Formation, E. jolensis is succeeded by Loxodonta africana at 130 ka, coincident with an intensely cool, dry interval marked by episodes of extreme drought. This marked the extirpation of Elephas on the continent. The intensity and increased rate of climate fluctuation may have played an important role in the demise of the specialist, grazing E. recki-E. jolensis lineage in favor of a generalist, mixed feeder such as L. africana.

Cenozoic formation and colonisation history of the New Zealand vascular flora based on molecular clock dating of the plastid rbcL gene

ABSTRACTA colonisation history for 411 extant genera and 477 lineages of the vascular flora of New Zealand was constructed using the plastid rbcL gene. Molecular clock crown ages suggest that the Eocene-Oligocene transition extinction at 33.9 Ma was critical to the development of the extant flora as few lineages, mostly ferns and conifers, predate this event. Based on crown dates, almost all extant angiosperm lineages have established after the Eocene-Oligocene transition extinction. The Oligocene marine transgression had little discernible impact on the formation of the extant flora, as at the culmination of the inundation (22.0–25.0 Ma) fifty extant lineages of vascular plant were present and another eight lineages originated during this time. The majority of extant species (89%) originated after the end of the Miocene Thermal Optimum at about 15.0 Ma. Nearly 50% of the extant species have evolved during mountain uplift and glaciation of the late Pliocene-Pleistocene (0–4.99 Ma). Therefore, despite a residual contribution from the Eocene, Oligocene and early to mid Miocene periods, the New Zealand vascular flora essentially originated in the late Miocene and after.

From cylindrical to non‐cylindrical foreland basin: Pliocene–Pleistocene evolution of the Po Plain–Northern Adriatic basin (Italy)

AbstractThe architecture of foreland basins and the resulting distribution of clastic sediments are related to the constant interplay between tectonics and sedimentation. Specifically, basin floor modifications strongly influence dimensions, continuity and connections of sand‐size and fine‐grained deposits. Given the increasing need to identify deep potential reservoir deposits, the large‐scale definition of clastic porous targets and their seals is a matter of interest for oil and gas industry. Here, we present the reconstruction of the Po Plain and Northern Adriatic Foreland Basin (with an extent of ca. 40,000 km2) and its Pliocene–Pleistocene evolution, as an example of a sedimentary clastic system controlled by strongly non‐cylindrical foreland geometry. The study is based on the basin‐scale mapping of six unconformity‐bounded sequences, performed by interpreting a dense network of seismic lines and correlating well‐log data. This provides a three‐dimensional model of the step‐by‐step evolution of the basin and a description of the sediment dispersal pattern. We found that the basin records the change from a continuous (cylindrical) to highly fragmented (non‐cylindrical) foredeep geometry during Late Pliocene. In the Northern Apennines case, the main factors driving the development of a non‐cylindrical geometry are mainly related to inherited inhomogeneity in the downgoing block linked to its Mesozoic extensional faulting, and the relative orientation of these lineaments with respect to the direction of orogen migration. During the late Pliocene–Pleistocene the two directions progressively became close to parallel, and the Northern Apennines system reacted changing from a cylindrical to a non‐cylindrical state.

Evolution of the Zonal Gradients Across the Equatorial Pacific During the Miocene–Pleistocene

Combining U k 0 37-and TEX 86-derived temperatures and oxygen isotopic values of mixed-layer and thermocline species from the IODP site U1338 (East Equatorial Pacific) and ODP Site 806 (West Equatorial Pacific) we assess the evolution of the zonal sea-surface temperature gradients and thermocline depth across the equatorial Pacific from the late Miocene through the Pleistocene. Data suggest a long-term shoaling of the thermocline along the equator throughout the Miocene-Pliocene that accelerated around 5.3 Ma. We identify a critical transition at about 3.8 Ma from a El-NinoNi˜Nino-like-dominated mean state during the late Miocene and early Pliocene to a La-Nina-like-dominated state during the late Pliocene-Pleistocene. This transition coincides with the restriction of the Indonesian seaway and the onset of ice growth in the northern hemisphere and in Antarctica that led to the long-term strengthening of the Walker circulation and affected low-latitude zonal gradient.

Plio-Pleistocene diversification and biogeographic barriers in southern Australia reflected in the phylogeography of a widespread and common lizard species

Palaeoclimatic events and biogeographical processes since the mid-Tertiary have played an important role in shaping the evolution and distribution of Australian fauna. However, their impacts on fauna in southern and arid zone regions of Australia are not well understood. Here we investigate the phylogeography of an Australian scincid lizard, Tiliqua rugosa, across southern Australia using mitochondrial DNA (mtDNA) and 11 nuclear DNA markers (nuDNA), including nine anonymous nuclear loci. Phylogenetic analyses revealed three major mtDNA lineages within T. rugosa, geographically localised north and south of the Murray River in southern Australia, and west of the Nullarbor Plain. Molecular variance and population analyses of both mtDNA and nuDNA haplotypes revealed significant variation among the three populations, although potential introgression of nuDNA markers was also detected for the Northern and Southern population. Coalescent times for major mtDNA lineages coincide with an aridification phase, which commenced after the early Pliocene and increased in intensity during the Late Pliocene-Pleistocene. Species distribution modelling and a phylogeographic diffusion model suggest that the range of T. rugosa may have contracted during the Last Glacial Maximum and the locations of optimal habitat appear to coincide with the geographic origin of several distinct mtDNA lineages. Overall, our analyses suggest that Plio-Pleistocene climatic changes and biogeographic barriers associated with the Nullarbor Plain and Murray River have played a key role in shaping the present-day distribution of genetic diversity in T. rugosa and many additional ground-dwelling animals distributed across southern Australia.

Deposition in a changing paleogulf: evidence from the Pliocene–Quaternary sedimentary succession of the Nile Delta, Egypt

Sedimentary complexes of ancient gulfs provide valuable information about paleoenvironmental dynamics. The study of several Pliocene–Pleistocene sections allowed reconstruction of the regional stratigraphical framework in the southwestern fringes of the Nile Delta. The Kafr El-Shiekh, the Gar El-Muluk, and the Kom El-Shelul formations of the Zanclean Age and the Wastani Formation of the Piacenzian Age constitute the Pliocene sedimentary succession in the study area. The establishment of 11 facies types related to 5 facies associations coupled with the results of the stratigraphical study indicate the existence of a paleogulf corresponding to the modern delta and lower valley of the Nile. This Nile Paleogulf appeared and reached its maximum spatial extent in the beginning of the Pliocene. Then, it retreated gradually and disappeared before the end of this epoch when alluvial sedimentation reestablished. There was significant flux of siliciclastic material to the study area. The Zanclean Flood in the Mediterranean Sea allowed marine incursion in the study area where the river valley incised during the precedent Messinian Salinity Crisis. Regional tectonic uplift and filling of the accommodation space with siliciclastic material from the eroded land were the main controls on the paleogulf evolution. Strengthened glaciation triggered global sea level fall, and alluvial deposition dominated the study area in the late Pliocene–Pleistocene.

Redescription of Pelobates praefuscus Khosatzky, 1985 and new records of Pelobates from the late Miocene–Pleistocene of Eastern Europe

A reexamination of the holotype frontoparietal of Pelobates praefuscus Khosatzky, 1985 from the Pliocene of Moldova and an investigation of newly referred frontoparietal reveal previously unknown characters for this species. P. praefuscus, considered a synonym of Pelobates fuscus, is regarded here as a separate species. It differs from P. fuscus in the presence of frontoparietal-squamosal contact and medial position of the foramen arteriae occipitalis and from all extant Pelobates in having the arteria orbitonasalis open posteriorly. The last character, previously known only in early Miocene Pelobates, is shown to be present in late Miocene and early Pliocene congeners, whereas in late Pliocene–Pleistocene congeners, the posterior part of the arteria orbitonasalis generally is covered ventrally by bone.