Paleosols and host rocks from the Middle–Upper Permian reference section of the Kazan Volga region,Russia: A case study

The Urzhumian (Wordian) and Severodvinian (Capitanian) reference section of the Monastery Ravine (Kazan Volga region, Russia), contains two siltstone lithofacies: (a) laminated and (b) massive. Depositional settings of the laminated siltstones can be interpreted as perennial to ephemeral lakes; depositional settings of the massive siltstones are interpreted as floodplains with soil cover and periodical silt influx in wet seasons. The bulk geochemistry of siliciclastics has revealed a high degree of weathering of both types of siltstone. The similar chemical composition, mineralogy, and grain size suggest the same provenance of silt material. Geochemical data indicate eastern source rocks, which are the Permian red beds of the Cis-Ural plains.The main genetic types of paleosols hosted in the massive siltstones in the studied section, include moderately developed Vertisols and Calcisols with drab-colored root traces, calcareous nodules, low chroma mottles, angular blocky peds and slickensides. These pedofeatures indicate in general a semi-arid climate with clear seasonality of rainfall. Major oxides of the paleosol matrix were used to estimate paleoprecipitation through the bases to alumina (ΣBases/Al) ratio and chemical index of alteration minus potassium (CIA-K) proxies. Estimates from Urzhumian paleosols indicate relatively low mean annual precipitation (MAP) of 390 mm/yr. The transition to the Severodvinian paleosols is marked by a noticeable MAP increase up to 777 mm/yr. This climate moistening coincides with changes in the morphology of paleosols from dolomitic with low redoximorphy to calcitic with gley horizons. The pedogenic carbonate nodules consisting of dolomicrite (5–10 μm) are very common in the Urzhumian paleosols and their morphology, micromorhology and isotopic features indicate the pedogenic origin of dolomite.Sedimentological and paleopedological features of the studied siltstones, as well as the location of the Volga-Ural basin in a mid-latitude position (25–32 °N) indicate a monsoonal character of precipitation during the Middle Permian.     

Soils,time, and primate paleoenvironments

Soils are the skin of the earth. From both poles to the equator, wherever rocks or sediment are exposed at the surface, soils are forming through the physical and chemical action of climate and living organisms. The physical attributes (color, texture, thickness) and chemical makeup of soils vary considerably, depending on the composition of the parent material and other variables: temperature, rainfall and soil moisture, vegetation, soil fauna, and the length of time that soil–forming processes have been at work. United States soil scientists¹ have classified modern soils into ten major groups and numerous subgroups, each reflecting the composition and architecture of the soils and, to some extent, the processes that led to their formation. The physical and chemical processes of soil formation have been active throughout geologic time; the organic processes have been active at least since the Ordovician.² Consequently, nearly all sedimentary rocks that were deposited in nonmarine settings and exposed to the elements contain a record of ancient, buried soils or paleosols. A sequence of these rocks, such as most ancient fluvial (stream) deposits, provides a record of soil paleoenvironments through time. Paleosols are also repositories of the fossils of organisms (body fossils) and the traces of those organisms burrowing, food–seeking, and dwelling activities (ichnofossils). Indeed, most fossil primates are found in paleosols. Careful study of ancient soils gives new, valuable insights into the correct temporal reconstruction of the primate fossil record and the nature of primate paleoenvironments.     

A new Serpukhovian (Mississippian) fossil flora from western Argentina: Paleoclimatic, paleobiogeographic and stratigraphic implications

An uppermost Mississippian (Serpukhovian) fossil flora from western Argentina is described for the first time. Its particular composition includes both, warm climate plants typical from the Pennsylvanian of Gondwana, namely pteridosperms, sphenophytes as well as arboreous lycopsids; and small lycopsids characteristic of cooler climates of pre-Serpukhovian times. A warm–temperate climate is inferred for this association, which fills a time gap between those Pennsylvanian and Mississippian classic floras previously known. The presence of Tomiodendron, Nothorhacopteris kellaybelenensis and Paracalamites allow the recognition of the Paraca Floral Realm in Argentina, supporting the existence of a nonglacial paleoclimate period, developed just before of the Bashkirian–Moscovian Gondwanan glaciation and after a latest Visean glaciation. It likewise would indicate the paleogeographic position of south west Gondwana, which would have acceded to a warm temperature latitudinal belt during Serpukhovian times. The recognition of this floral assemblage has relevant biostratigraphic and lithostratigraphic implications for the western margin of Gondwana. It defines a new zone for western Argentina, herein named Frenguellia eximia–Nothorhacopteris kellaybelenensis–Cordaicarpus cesarii (FNC) zone, which is recorded in the oldest known lithostratigraphic unit from the Paganzo Basin, the Loma de los Piojos Formation nom. nov.     

Late Mississippian vertebrate palaeoecology and taphonomy,Buffalo Wallow Formation,western Kentucky,USA

Aquatic vertebrates are reported from several facies of the Late Mississippian (Chesterian/Elviran/Serpukhovian) Buffalo Wallow Formation in western Kentucky, USA. Rhizodont bones and the partially articulated skeleton of a large anthracosaur (proterogyrinid) were found in rocks interpreted as a fluvial‐estuarine palaeochannel. Smaller, disarticulated tetrapod remains (anthracosaurs, whatcheeriids) were found in a weathered siltstone in an apparent channel margin‐sand flat facies. A putative oxbow‐abandoned channel facies contains skeletal elements of rhizodonts (cf. Rhizodus), colosteiids, Gyracanthus, Ageleodus, Cynopodius, xenacanthoids and palaeonisiciforms. Near the top of the channel fill, lungfish (cf. Tranodis) are found in carbonate‐rich nodules, which appear to be aestivation burrows. A presumed lacustrine facies contained a near‐complete colosteid. Thinning section, palaeosols, pedogenically‐altered carbonates and missing strata suggest tectonic and climatic overprints upon these depositional sequences. Multiple, incised channels in a low‐accommodation setting are interpreted to have provided local faunal traps for aquatic vertebrates. Late Mississippian palaeoclimate changes may have caused water table fluctuations, which might have aided in trapping and preserving aquatic vertebrates.     

Paleosols,trace fossils,and precipitation estimates of the uppermost Triassic strata in northern New Mexico

This study provides a detailed pedogenic evaluation of two Upper Triassic (Late Norian through Rhaetian) stratigraphic intervals in New Mexico in order to assess the climate and ecology of the Latest Triassic, which ended in a mass extinction. The two study areas are located in north–central and east-central New Mexico and are separated by 200 km. Each section contains abundant paleosols of varying maturity with features that reflect an arid to semiarid climate. There is little pedogenic variation throughout the strata at each location, and a typical paleosol profile is about 1 m thick and has an AB–Bw–Bk–BC horizon succession. Bkm, Bss, Bssk, or Bssg horizons are present in some paleosols. Micromorphological features suggest dominantly well-drained sola (e.g., abundant carbonate nodules, illuviated clay) with minor periods of moist or saturated conditions (e.g., FeMn concretions, FeMn coatings and hypocoatings, sepic-plasmic fabrics). Trace fossils are abundant in these strata and are dominated by Taenidium serpentinum and root traces. Depth-to-carbonate functions estimate that mean annual precipitation was between 200 and 450 +/? 95 mm. Relative to location 1 (eastern New Mexico), location 2 (north–central New Mexico) produced higher paleo-precipitation estimates and has stronger and more abundant sepic-plasmic fabrics in thin sections. The presence of a gleyed paleosol, Camborygma eumnkenomos, and slickensides at location 2 also suggests conditions wetter than at location 1. Taxonomically, all of the paleosols in this study appear to be Entisols or Aridisols and can be grouped into seven representative pedotypes of varying maturity. By comparing these paleosols to modern soils, this study demonstrates that the Late Triassic Western Interior during the Late Norian to Rhaetian was arid to semiarid and supported a desert shrub environment that had localized and periodic moist or saturated soil conditions.     

Late Mississippian to Early Pennsylvanian conodont biofacies in central Montana

Later Mississippian (upper Chesterian) to Early Pennsylvanian (lower Morrowan) conodont faunas were recovered from limestones and calcareous mudstones of the Alaska Bench Formation in central Montana. These faunas define four biofacies, each recognized by the dominance of a particular single element genus for which the biofacies is named. The Adetognathus biofacies represents lagoonal, tidal flat, and barrier sediments. The Declinognathodus/Idiognathoides biofacies represents a deposition in shallow, open marine, offshore conditions. The Rhachistognathus biofacies represents a transitional environment between restricted, intertidal environments and normal marine, offshore environments. The Neognathodus biofacies represents shallow-water bay or lagoonal deposition, where environmental controls have effectively excluded other conodont faunas. The investigation of conodont biofacies provides improved biostratigraphic and paleoenvironmental uses of conodonts.     

Late glacial and Holocene environmental changes inferred from sediments in Lake Myklevatnet,Nordfjord, western Norway

Late Glacial and Holocene environmental changes were reconstructed using physical, chemical and biological proxies in Lake Myklevatnet, Allmenningen, (5º13′17″E, 61º55′13″N) located at the northern side of Nordfjorden at the coast of western Norway. Myklevatnet (123 m a.s.l.) lies above the Late Glacial marine limit and contains sediments back to approximately 14,300 years before a.d. 2000 (b2k). Because the lake is located ~48 km beyond the margin of the Younger Dryas (YD) fjord and valley glaciers further inland, and did not receive glacier meltwater from local glaciers during the YD, the lake record provides supplementary information to Lake Kråkenes that received glacial meltwater from a local YD glacier. Lake Myklevatnet has a small catchment and is sensitive to Late Glacial and Holocene climate and environmental changes in the coastal region of western Norway. The age-depth relationship was inferred from a radiocarbon- and tephra-based smoothing-spline model with correlated ages from oxygen isotope maxima and minima in the Late Glacial sequence of the NGRIP ice core (in years b2k) to refine the basal chronology in the Myklevatnet record. The results indicate a two-step YD warming, colder early YD temperatures than in the later part of the YD, and considerably more climate and environmental variability during the late Holocene in western Norway than recorded previously in the oxygen isotopes from Greenland ice cores. The Myklevatnet record is also compared with other Late Glacial and Holocene terrestrial and marine proxy reconstructions in the North Atlantic realm.     

Tetrapod Footprint Biostratigraphy and Biochronology

Tetrapod footprints have a fossil record in rocks of Devonian-Neogene age. Three principal factors limit their use in biostratigraphy and biochronology (palichnostratigraphy): invalid ichnotaxa based on extramorphological variants, slow apparent evolutionary turnover rates and facies restrictions. The ichnotaxonomy of tetrapod footprints has generally been oversplit, largely due to a failure to appreciate extramorphological variation. Thus, many tetrapod footprint ichnogenera and most ichnospecies are useless phantom taxa that confound biostratigraphic correlation and biochronological subdivision. Tracks rarely allow identification of a genus or species known from the body fossil record. Indeed, almost all tetrapod footprint ichnogenera are equivalent to a family or a higher taxon (order, superorder, etc.) based on body fossils. This means that ichnogenera necessarily have much longer temporal ranges and therefore slower apparent evolutionary turnover rates than do body fossil genera. Because of this, footprints cannot provide as refined a subdivision of geological time as do body fossils. The tetrapod footprint record is much more facies controlled than the tetrapod body fossil record. The relatively narrow facies window for track preservation, and the fact that tracks are almost never transported, redeposited or reworked, limits the facies that can be correlated with any track-based biostratigraphy.

A Devonian-Neogene global biochronology based on tetrapod footprints generally resolves geologic time about 20 to 50 percent as well as does the tetrapod body fossil record. The following globally recognizable time intervals can be based on the track record: (1) Late Devonian; (2) Mississippian; (3) Early-Middle Pennsylvanian; (4) Late Pennsylvanian; (5) Early Permian; (6) Late Permian; (7) Early-Middle Triassic; (8) late Middle Triassic; (9) Late Triassic; (10) Early Jurassic; (11) Middle-Late Jurassic; (12) Early Cretaceous; (13) Late Cretaceous; (14) Paleogene; (15) Neogene. Tetrapod footprints are most valuable in establishing biostratigraphic datum points, and this is their primary value to understanding the stratigraphic (temporal) dimension of tetrapod evolution.     

Biomass, Litter, and Soil Respiration Along a Precipitation Gradient in Southern Great Plains, USA

Knowledge of how ecosystem carbon (C) processes respond to variations in precipitation is crucial for assessing impacts of climate change on terrestrial ecosystems. In this study, we examined variations of shoot and root biomass, standing and surface litter, soil respiration, and soil C content along a natural precipitation gradient from 430 to 1200 mm in the southern Great Plains, USA. Our results show that shoot biomass and soil respiration increased linearly with mean annual precipitation (MAP), whereas root biomass and soil C content remained relatively constant along the precipitation gradient. Consequently, the root/shoot ratio linearly decreased with MAP. However, patterns of standing, surface, and total litter mass followed quadratic relationships with MAP along the gradient, likely resulting from counterbalance between litter production and decomposition. Those linear/quadratic equations describing variations of ecosystem C processes with precipitation could be useful for model development, parameterization, and validation at landscape and regional scales to improve predictions of C dynamics in grasslands in response to climate change. Our results indicated that precipitation is an important driver in shaping ecosystem functioning as reflected in vegetation production, litter mass, and soil respiration in grassland ecosystems.     

Calcium Nodules as a Proxy for Quaternary Paleoclimate Change on China’s Loess Plateau

Different proxies have been used to investigate Quaternary paleoclimate change. Here, we used weathering of calcium nodules in paleosols on China’s Loess Plateau as a proxy for Quaternary paleoclimate changes to provide an alternative indicator of these changes. Paleosol and carbonate nodules were collected from Luochuan and Lantian counties in Shaanxi Province, China. We found that this approach allowed quantitative reconstruction of temperature, rainfall, soil mineral composition, and the effects of weathering and leaching. The changes in carbonate content in the loess and paleosol sequences were controlled by alternating dry and wet climatic conditions. Nodule formation conditions were directly affected by the leaching and migration of elements. The loess and paleosol sequences developed calcium nodules, and their formation was closely related to the rainfall and leaching characteristics of the paleoclimate. The paleoclimate and soil minerals affected the vegetation types and directly influenced changes in the soil. During formation of the calcium nodules, the surface vegetation evolved slowly, and the number of species and quantity of vegetation both decreased.     

Fossil bee nests,coleopteran pupal chambers and tuffaceous paleosols from the Late Cretaceous Laguna Palacios Formation,Central Patagonia (Argentina)

The Late Cretaceous Laguna Palacios Formation in Central Patagonia (San Jorge Basin), southern South America, is composed of tuffaceous deposits supplied by periodical volcanic ash falls partly reworked by rivers, on broad plains. Variations in ash-fall rates allowed the formation of stacked, mature paleosols, which are one of the most characteristic features of this formation. The mature paleosols show well-developed horizons, ped structure and bear an intricate network of trace fossils mostly produced by small roots and invertebrates. Two different insect trace fossils could be recognized in this formation: sweat bee nests and coleopteran pupal chambers. Fossil bee nests are composed of inclined tunnels with cells attached to them by means of short necks, a typical construction of bees of the subfamily Halictinae. Similar halictine constructions were reported from the Cretaceous of the USA. Coleopteran pupal chambers are discrete, ovoid structures, having an internal cavity with a smooth surface, and an outer wall of lumpy appearance composed of different layers of soil material. They are commonly constructed by the larvae of different families of Coleoptera. Similar trace fossils were previously reported from the Asencio Formation (Late Cretaceous–Early Tertiary) of Uruguay and from the Djadokhta Formation of Mongolia (Late Cretaceous). These trace fossils constitute some of the only paleontological data from the Laguna Palacios Formation, allowing inferences about its paleoecology, paleoclimatology and paleogeography. Ecological preferences of Halictinae, as well as some features of the nests, suggest a temperate, seasonal climate and an environment dominated by low vegetation for the Laguna Palacios Formation, which is also compatible with sedimentologic and pedogenic evidence. The morphology of the nests, typical of North American halictinae, adds more evidence to the hypothesis of the existence of faunal interchange between North and South America by the Late Cretaceous. The fossil nests constitute some of the oldest evidence of bees in the fossil record, the third known record of bees of Cretaceous age and the first for the Southern Hemisphere. The two traces described are, together with those of Dakota and the Gobi Desert, the only trace fossils from paleosols of Cretaceous age that can be certainly attributed to insects.     

Multi-proxy paleosol evidence for middle and late Triassic climate trends in eastern Utah

Prior investigations suggest that alluvial lowlands of Pangea in the southwestern U.S.A. during the middle to late Triassic experienced an arid to semiarid climate with significant seasonality. Our investigation finds evidence for a global pluvial episode from paleosols in the middle to late Triassic section of eastern Utah. Multi-proxy paleosol evidence is used to quantify rainfall amounts, ambient temperatures and atmospheric CO₂ concentrations and infer associated plant formations related to ecosystem persistence. Rainfall estimates are derived from geochemical molecular weathering ratios; temperature and atmospheric CO₂ levels from stable oxygen and carbon isotopes of pedogenic carbonate, respectively; and ecosystem reconstruction by a combination of climate indexes and paleosol characteristics. Eight pedotypes were identified and include poorly drained aquic Entisols (Fisher), well-drained non-aquic Entisols (Salt Valley), calcic Aridisols (Castle Valley), calcic Inceptisols (Moab), cambic (Ute) and calcic (La Sal) Vertisols, dystric Inceptisols (Kokopeli), and argillic Alfisols (Slickrock). The middle Triassic Moenkopi Formation (Anisian) was dominated by Castle Valley paleosols with mean annual rainfall between 300 and 400 mm and mean annual temperature between 13 and 23 °C (mesic to hyperthermic). Based on these climate indexes and root traces, the associated plant formation was most likely desert shrub or dry woodland. The lower Chinle Formation (Carnian) contains a succession of Ute and La Sal paleosols that changed up-section to Kokopeli, Fisher and Slickrock paleosols. In accordance with geochemical and isotopic signatures from these pedotypes, rainfall amounts initially increased to between 700 and 900 mm, and then to between 1300 and 1400 mm. Temperatures estimated from the La Sal paleosol are approximately 18 °C (thermic) at this time. The lower Chinle marks a transition from dry woodland to open forest that appears to correlate with the formation of the Petrified Forest Member in Arizona. The upper Chinle Formation (Carnian-Norian) reveals a return to semiarid to subhumid conditions and the formation of Castle Valley, Moab and Salt Valley paleosols, all of which appear to have supported desert shrub or dry woodlands. Rainfall amounts decreased to between 400 and 600 mm with temperatures eventually increasing to 29 °C (hyperthermic). Using the paleosol isotopic barometer, atmospheric CO₂ estimates generally correlate with other proxy for the Triassic. The well-developed Alfisols and noncalcareous Inceptisols identified during the Carnian of the lower Chinle correlate with a previously identified global pluvial episode based on sedimentological and marine isotopic evidence, possibly in response to rifting of Pangea. It should not be assumed that the middle to late Triassic in continental alluvial lowlands supported a uniform, semiarid to arid climate, with strong seasonality.     

The evolutionary diversification of seed size: using the past to understand the present

The Devonian origin of seed plants and subsequent morphological diversification of seeds during the late Paleozoic represents an adaptive radiation into unoccupied ecological niche space. A plant's seed size is correlated with its life-history strategy, growth form, and seed dispersal syndrome. The fossil record indicates that the oldest seed plants had relatively small seeds, but the Mississippian seed size envelope increased significantly with the diversification of larger seeded lineages. Fossil seeds equivalent to the largest extant gymnosperm seeds appeared by the Pennsylvanian, concurrent with morphological diversification of growth forms and dispersal syndromes as well as the clade's radiation into new environments. Wang's Analysis of Skewness indicates that the evolutionary trend of increasing seed size resulted from primarily passive processes in Pennsylvanian seed plants. The distributions of modern angiosperms indicate a more diverse system of active and some passive processes, unbounded by Paleozoic limits; multiple angiosperm lineages independently evolved though the upper and lower bounds. Quantitative measures of preservation suggest that, although our knowledge of Paleozoic seeds is far from complete, the evolutionary trend in seed size is unlikely to be an artifact of taphonomy.     

The youngest record of Carcharopsis (Chondrichthyes) from the Pennsylvanian of Xinjiang Uyghur Autonomous Region,China

A chondrichthyan tooth having a serrated edge, from the Late Pennsylvanian of Xinjiang Uyghur Autonomous Region, China, was identified as Edestus sp. [Cheng, Z., Lucas, S.G., Zidek, J., 1996. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte 1996 (11), 701-707]. Because of the lack of bilateral symmetry, the tooth does not belong to Edestus or any other known edestoid. It is too incomplete for a definite identification, but its features are consistent with Carcharopsis, which also has serrated teeth, and not with any other described late Paleozoic chondrichthyan genus. If it is Carcharopsis, it is the latest occurrence of the genus, which was previously known only from the Mississippian and the Early Pennsylvanian.     

Assessment of soil and vegetation changes due to hydrologically driven desalinization process in an alkaline wetland,Hungary

This study investigates a soil–water–vegetation system in a drying-out alkaline sodic wetland altered by climate change and artificial drainage by evaluating the habitat pattern and the physical and chemical attributes of the upper soil. The spatial and temporal alteration of the vegetation was monitored by detailed coenological investigations and habitat mapping during a 13-year period (2002–2014) to analyse the succession trend of the habitat in the changing environment. The spatial structures of the physical and chemical attributes of the soil were surveyed by topsoil sampling along a regular network to detect the desalinization process and to reveal the discrepancies between the soil attributes and the typical habitats because anomalies between the habitat and its optimal soil properties can project a possible vegetation change in a dynamically changing sodic ecosystem. The micro-topography was investigated to detect the effect of the elevation difference on the hydrologic conditions, soil and vegetation attributes. Statistical analyses were performed to describe the characteristic pedological processes and the spatial structures of the soil parameters. An overlapping analysis was conducted to compare the soil, vegetation pattern and topography to explore the relationships in the altering soil–water–vegetation system.Rapid alterations of the habitats, species composition, and soil desalinization processes were clearly recognised. The rate of change reflects degradation beyond the natural dynamics of vegetation processes. The desalinization process was extremely rapid due to the sandy sediment. The significant changes in the vegetation and soil pattern led to the loss of diversity in the short term; annual salt pioneer swards and Puccinellia swards became highly threatened. The main driving factors in the desalinization process are water shortage caused by artificial drainage and climate change, furthermore extreme high precipitation which intensifies leaching. The degradation process can be mitigated by adequate water management because habitats have a high naturalness reflecting good regeneration potential.     

A late glacial to present diatom record from Lake Euramoo, wet tropics of Queensland, Australia

A new diatom record from Lake Euramoo on the Atherton Tableland, north Queensland, Australia is used to assess regional climate change and variability and their links to forcing at a local to global scale. The major factor driving diatom composition in the approximately fifteen thousand-year record appears to be regional moisture availability. Patterns of diatom preservation and other indicators, particularly sediment organic content, suggest that permanent deep water formed at the site from ca. 15,000 cal. yr BP. However, between 13,800 and 11,500 cal. yr BP, there was a notable phase of lower lake levels and effective precipitation. The timing and duration of this phase does not correspond to large-scale climate phenomena such as the Antarctic Cold Reversal or the Younger Dryas and supports emerging evidence for a variable climate regime in the south-west Pacific during the late glacial transition.The Early to Mid Holocene record is one of remarkable stability with 5000 years of sustained dominance by the planktonic diatom Aulacoseira ambigua. Conversely, the Mid to Late Holocene record is marked by distinct diatom variability superimposed on a series of sustained shifts in composition. Accentuated Late Holocene climate variability may aid in explaining intensified land use in indigenous populations and also suggests that Europeans may have arrived in the landscape at the time it was most vulnerable to perturbation.     

Large Pelycosaur Footprints from the Lower Pennsylvanian of Alabama,USA

Relatively large tetrapod footprints from Lower Pennsylvanian strata of the Pottsville Formation in the Warrior basin coal field of Alabama were previously assigned to the ichnogenus Attenosaurus. However, three morphotypes are present, and we assign these tracks to Attenosaurus, a new ichnogenus (Alabamasauripus) and Dimetropus. Most of these tracks apparently were made by large pelycosaurs, for which there is no bone record older than Late Pennsylvanian.     

The Role of Climate in Settlement and Landscape Change in the North Atlantic Islands: An Assessment of Cumulative Deviations in High-Resolution Proxy Climate Records

In order to assess possible contributions of climate change to the human ecology of the North Atlantic islands we evaluate the utility of cumulative deviations from the mean, calculated for the Greenland ice core storm frequency proxy (GISP2 Na⁺) and sea ice proxy (GISP2 chloride excess). Our aim is to identify episodes of unpredictable change in the context of long-term trends of cultural and environmental development. Key changes are identified in the proxy climate records in 975 and 980 ad, 1025 and 1040 ad, 1180 ad, 1425 and 1450 ad, and 1520 and 1525 ad. Some of these changes are consistent with those inferred from new studies of the palaeoecological record of the Faroes. This indicates that the cumulative deviation measure could give greatest prominence to the most important climate changes affecting landscapes and settlement (such as the changes of 1425 and 1450 ad and their immediate aftermath), rather than extreme events, such as great single storms.     

New insights into the reading of Paleozoic plant fossil record discontinuities

Studying the discontinuity patterns of Paleozoic vascular plants provides a global vision of these key events from the multivariate methods viewpoint. Non-metric multidimensional scaling, detrended correspondence analysis and cluster analysis have been employed together with a set of diversity and abundance measures and an evaluation of the geologic constraints from the plant fossil record data. The results reveal four clear significant discontinuities in terms of taxonomic composition and record representativeness during the early-middle Devonian, Devonian–Carboniferous, Mississippian–Pennsylvanian and early-late Permian. Due to the controversial character of the plant fossil record data and the effect of mass extinction events, the results can be explained in taxonomic turnover and ecological reorganisation terms which emphasise the crucial role of the geologic constrains in paleobiological inference.     

Ancient DNA from the Schild site in Illinois: Implications for the Mississippian transition in the Lower Illinois River Valley

Archaeologists have long debated whether rapid cultural change in the archaeological record is due to in situ developments, migration of a new group into the region, or the spread of new cultural practices into an area through existing social networks, with the local peoples adopting and adapting practices from elsewhere as they see fit (acculturation). Researchers have suggested each of these explanations for the major cultural transition that occurred at the beginning of the Mississippian period (AD 1050) across eastern North America. In this study, we used ancient DNA to test competing hypotheses of migration and acculturation for the culture change that occurred between the Late Woodland (AD 400–1050) and Mississippian (AD 1050–1500) periods in the Lower Illinois River Valley. We obtained sequences of the first hypervariable segment of the mitochondrial genome (mtDNA) from 39 individuals (17 Late Woodland, 22 Mississippian) interred in the Schild cemetery in western Illinois, and compared these lineages to ancient mtDNA lineages present at other sites in the region. Computer simulations were used to test a null hypothesis of population continuity from Late Woodland to Mississippian times at the Schild site and to investigate the possibility of gene flow from elsewhere in the region. Our results suggest that the Late Woodland to Mississippian cultural transition at Schild was not due to an influx of people from elsewhere. Instead, it is more likely that the transition to Mississippian cultural practices at this site was due to a process of acculturation. Am J Phys Anthropol 156:434–448, 2015. © 2014 Wiley Periodicals, Inc.