Paleoecology

The palaeoecology of the primitive, limbed snake Pachyrhachis is reevaluated. Previously considered to have been preserved in a shallow bay with a nearby freshwater source, it is here demonstrated to have inhabited an inter‐reef basin. Evidence for this comes from the position of the nearest palaeoshoreline (450 km away), the finely laminated carbonate mudstones, and the absence of bioturba‐tion, alluvium, and unequivocally terrestrial or freshwater taxa. Marine adaptations of Pachyrhachis include the laterally compressed body and heavily ossified (pachyostotic) vertebrae and ribs. Hydrodynamic considerations indicate that it was a slow swimmer, and thus an ambush rather than pursuit predator. Morphology of the anterior vertebrae suggests that the strike muscles were well‐developed. The narrow head and neck might have been adaptations to reduce water resistance during rapid lunges, and/or to forage in burrows or tight crevices.

Aim  There remains some uncertainty concerning the causes of extinctions of Madagascar’s megafauna. One hypothesis is that they were caused by over-hunting by humans. A second hypothesis is that their extinction was caused by both environmental change and hunting. This paper systematically addresses the second hypothesis through examination of two new pollen records from south-eastern Madagascar alongside other published records across the island.Location  South-eastern Madagascar.Methods  We reconstructed past vegetation and fire dynamics over the past 6000 years at two sites in south-eastern Madagascar (Ste-Luce) using fossil pollen and charcoal contained in sedimentary sequences. We investigated drivers of vegetation changes and how these, in turn, influenced faunal species in the south-east, using published climatic, archaeological and faunal records. Further, we also used published records to provide a synthesis of environmental changes on the whole island.Results  Vegetation reconstructions indicate that the mosaic vegetation in the region of Ste-Luce was highly dynamic in response to climatic changes. The open woodland, surrounding the littoral forest, transformed into an ericoid grassland between c. 5800 and 5200 cal. yr bp, possibly in response to a moderate drought recorded during this period. The littoral forest was more stable between c. 5100 and 1000 cal. yr bp, with only some minor compositional changes c. 2800 cal. yr bp and between c. 1900 and 1000 cal. yr bp. Significant forest decline, however, is observed at c. 950 cal. yr bp, coinciding with a drought and a marine surge. A comparison of these results with a synthesis of published vegetation records across the island shows asynchronous vegetation changes in response to various droughts during the Holocene, except for the 950 cal. yr bp drought event, with evidence of widespread vegetation transformations and fires across the island.Main conclusions  Pronounced climatic desiccation between 1200 and 700 cal. yr bp may have been the slow driver framing and triggering vegetation transformations and decline in megafaunal populations. In addition, hunting by drought-impacted human inhabitants and competition with newly introduced cattle would have amplified the impacts on megafaunal populations, leading to numerous extinctions in this period.

Given the difficulty of separating the three Picea species—P. glauca, P. mariana, and P. rubens (white, black, and red spruce)—in the pollen record, little is known about their unique histories in eastern North America following deglaciation. Here we report the first use of a classification tree analysis (CART) to distinguish pollen grains of these species. It was successfully applied to fossil pollen from eight sites in Maine and one in Massachusetts. We focused on the late glacial/early Holocene (14,000 to 8000 cal yr B.P.) and the late Holocene (1400 cal yr B.P. to present)—the two key periods since deglaciation when Picea has been abundant in the region. The result shows a shift from a Picea forest of P. glauca and P. mariana in the late glacial to a forest of P. rubens and P. mariana in the late Holocene. The small number of P. rubens grains identified from the late glacial/early Holocene samples…

Determining the diet of an extinct species is paramount in any attempt to reconstruct its paleoecology. Because the distribution and mechanical properties of food items may impact postcranial, cranial, mandibular, and dental morphologies related to their procurement, ingestion, and mastication, these anatomical attributes have been studied intensively. However, while mechanical environments influence skeletal and dental features, it is not clear to what extent they dictate particular morphologies. Although biomechanical explanations have been widely applied to extinct hominins in attempts to retrodict dietary proclivities, morphology may say as much about what they were capable of eating, and perhaps more about phylogenetic history, than about the nature of the diet. Anatomical attributes may establish boundary limits, but direct evidence left by the foods that were actually (rather than hypothetically) consumed is required to reconstruct diet. Dental microwear and the stable light isotope chemistry of tooth enamel provide such evidence, and are especially powerful when used in tandem. We review the foundations for microwear and biogeochemistry in diet reconstruction, and discuss this evidence for six early hominin species (Ardipithecus ramidus, Australopithecus anamensis, Au. afarensis, Au. africanus, Paranthropus robustus, and P. boisei). The dietary signals derived from microwear and isotope chemistry are sometimes at odds with inferences from biomechanical approaches, a potentially disquieting conundrum that is particularly evident for several species. Am J Phys Anthropol 148:285–317, 2012. © 2012 Wiley Periodicals, Inc.

Xiphosurids are an archaic group of aquatic chelicerate arthropods, generally known by the colloquial misnomer of ‘horseshoe crabs’. Known from marine envi- ronments as far back as the early Ordovician, horseshoe crabs are generally considered ‘living fossils’ – descendants of a bradytelic lineage exhibiting little morphological or ecological variation throughout geological time. However, xiphosurids are known from freshwater sediments in the Palaeozoic and Mesozoic; furthermore, the contention that xiphosurids show little morphological variation has never been tested empirically. Attempts to test this are hampered by the lack of a modern phylogenetic framework with which to explore different evolutionary scenarios. Here, I present a phylogenetic analysis of Xiphosurida and explore patterns of morphospace and environmental occupation of the group throughout the Phanerozoic. Xiphosurids are shown to have invaded non-marine environments indepen- dently at least five times throughout their evolutionary history, twice resulting in the radiation of major clades – bellinurines and austrolimulids – that occupied novel regions of morphospace. These clades show a convergent ecological pattern of differentiation, speciation and subse- quent extinction. Horseshoe crabs are shown to have a more dynamic and complex evolutionary history than previ- ously supposed, with the extant species representing only a fraction of the group’s past ecological and morphological diversity.

Disulcate pollen grains belonging to the genus Dicolpopollis have a distinct morphology. The pollen of this genus has characteristics in common with pollen of the modern plant Calamus which is a climbing rotan palm growing on the riparian margins of peat swamps. Dicolpopollis-type pollen are shown to have been abundant especially in the coal seams. Dicolpopollis is mostly found in the Tertiary rocks forming acme zones especially in the Oligocene except for a few occurrences and indicates probably a subtropical dimate.

Native plant communities support a diverse biota of invertebrates, birds, and other wildlife, and are therefore essential to the health of ecosystems. Agriculture and urban development have eliminated most native plant communities through forest clearing and introduction of exotic, invasive plants. Prior to European settlement, bottomland hardwood forests prevailed along broad floodplains within the lower Mississippi alluvial valley. Dominant taxa included Taxodium distichum (L.) Rich. (bald cypress), Quercus spp. (oaks), Carya spp. (hickories), Fraxinus pennsylvanica (green ash), Liquidambar styraciflua (sweetgum), Celtis laevigata (sugarberry), Ulmus spp. (elms), and Nyssa spp. (gums). Much of this forested area, however, has been cleared and used for agricultural purposes or urban development. Bottomland hardwood forests, situated along the Mississippi River, are associated with the Mississippi Flyway, a bird migration route heavily utilized by migratory waterfowl, songbirds, and shorebirds for food, water, and shelter. In this preliminary study, woody plant species (trees and shrubs) occurring on the 134 hectare Delta State University campus (33844.7560N, 90844.0260W) were identified and documented. At present 46 families, 77 genera, and 125 species have been recognized. Only 66 species are native to the state of Mississippi. Only 41 species are native to the Mississippi Delta. We encourage the planting of more native woody plants representative of bottomland hardwood forests that will benefit migratory wildlife and enhance native habitat and food availability.

This paper presents the first record of the species Valgipes bucklandi in Rio Grande do Norte state, in the Brazilian Intertropical Region (BIR). This occurrence extends the distribution of this taxon in the BIR. Taphonomic information recovered from this finding indicated that the carcass was probably exposed in a hot and dry environment, whereas carbon isotope data revealed that V. bucklandi had a browser diet (δ13C = −10.17‰), living in more closed environments.► New occurrence of Valgipes bucklandi in Brazil. ► Expansion of its distribution in Brazilian Intertropical Region. ► Habitat and paleoecology information of this species.

Spiral-shaped foraging trace fossils, assigned to the graphoglyptid cf. Spirorhaphe azteca, are reported from an Early Permian intertidal flat in the Robledo Mountains of southern New Mexico, USA. Remarkably similar spiral-shaped structures are produced in modern intertidal flats by the paraonid polychaete Paraonis fulgens, and function as traps to capture mobile microorganisms migrating in the sediment in response to tides. We envisage a similar function for the Early Permian trace fossils. Previous studies have suggested that the lack of P. fulgens–type traces from ancient intertidal deposits indicates that such behavior only evolved geologically recently in such settings. However, this report demonstrates that such specialized foraging behavior was present in intertidal settings by at least the Early Permian. Graphoglyptids are typical of deep-marine settings, and characteristic of the Nereites ichnofacies. This represents their first undoubted occurrence in intertidal facies in the geological record. We postulate that the occurrence of graphoglyptids in deep-marine and intertidal settings is related to the predictability of resources. The scarcity of intertidal graphoglyptids in the geological record is most likely a preservational effect.

The “event” has recently emerged among social sciences as a debated concept through which to explore social practices and historical change. Instead of focusing on processes or long term trajectories of natural and social systems, as has been the dominant trend during the last decades, the intention is to grasp the specificity of given moments and to understand their historical relevance. The present text delves into the philosophical background of the concept “event” and its relevance to the present discussion on the natural and ideological construction of reality. Meanings and pitfalls of the concept are explored before a series of definitions are proposed, in order to establish the necessary epistemological background for such an approach.

Climate change, a timely topic, cannot be understood solely by analyzing modern-day ecosystems. Sediment stratigraphy from tidal marshes is an important source of paleoecological data, as these ecosystems experience high rates of deposition and preserve organic material well. Although Hudson River Valley marshes have been extensively researched, work has focused on the four areas protected by the Hudson
River National Estuarine Research Reserve (HRNERR). The marshlands of Haverstraw in Rockland County are comparable to the HRNERR sites in their capacity for biodiversity, carbon sequestration, and other important ecological functions. They are, however, understudied. This study uses loss-on-ignition and macrofossil analysis in combination with X-ray fluorescence spectroscopy to construct a high-resolution
paleoenvironmental record. Biotic and geochemical zones have been identified and correlated with archaeological and historical data to assess the influence of anthropogenic activity in the area. The organic:inorganic maxima evidenced likely correspond to a preindustrial period, characterized by burning events associated with increasing populations and concentrated settlement, as well as agricultural practices. Invasive species are prevalent, but certain key native species, notably Acorus americanus (American Sweet Flag), persist today. Exponential increases in heavy metal concentrations likely result from industry in the area but have declined following cessation of this activity and introduction of unleaded gasoline. Understanding historical human impacts is vital for predicting the ramifications of future development as well as establishing protocols for conservation and restoration.

Retrospective studies focussing on forest dynamics using fossil and genetic data can provide important keys to prepare forests for the future. In this study we analyse the impact of past climate and anthropogenic changes on Larix decidua Mill. (European larch) populations based on a new range-wide fossil compilation encompassing the last 130 ka and on recently produced genetic data (nuclear, mitochondrial). Results demonstrate that during the last 130 ka L. decidua persisted close to its current distribution range and colonized vast areas outside this range during the first two early Weichselian interstadials (c. 87-109 ka and c. 83-78 ka), reaching a distributional maxima in the north-central European lowlands. Some fossil sites point to notably rapid responses to some abrupt climate events DansgaardeOeschger cycles and Heinrich Events). Combined fossil and genetic data identify at least six MIS 2 refuges and postglacial recolonization pathways. The establishment of extant L. decidua forests dates back to the first two millennia of the Holocene (c. 11.5-9.5 ka) and the onset of anthropogenic impact was inferred since the late Neolithic (c. 6 ka), with major changes occurring since the Bronze Age (c. 4 ka). During the last 300 years human-induced translocations resulted in recent admixture of populations originating from separate refuges. Altogether, the results of this study provide valuable clues for developing sustainable conservation and management strategies targeting ancient genetic lineages and for studying evolutionary issues.

PALEOENVIRONMENTAL MEANING OF THE PRESERVED FAUNA IN THE
TREMEMBÉ FORMATION, TAUBATÉ BASIN, SÃO PAULO, BRAZIL

This work comprised the study of the Tremembé formation of Taubaté Basin, São Paulo state. Basin analysis studies were based on faunal data, which allows a better understanding of the paleoenvironments usually interpreted only by geological data or isolated taxonomic groups. The faunal representatives of the Tremembé Formation were inventoried and the diversity reached 43 species of insects, 13 of mammals, 10 of fishes, 8 of crustaceous and birds, 3 of reptiles, 2 of amphibious, 2 of mollusk and 1 of arachnids, annelids and spongy. Paleoanvironmental interpretation based on geological aspects and fossil plants basin was made over literature. These studies confirmed the existence of a great non oligomitic paleolake rich in aquatic plants and algae suggesting a high primary productivity. The lake water was alkaline, with a pH around 7-9. Most of the birds’ and mammals’ species, as well as paludal vegetation, lived around the lake. There was also a complex and  dense forest mainly composed of angiosperms, where selective animals fed. In the  highest region (dry and cold areas), diverse gymnosperms were identified by their pollens. The weather of the valley was moist with low seasonality, excepted by one great period of aridity registered over the bentonitic clay. All the data are consistent with Deseadan age (late Oligocene-early Miocene).

A Formação Tremembé da bacia de Taubaté foi estudada dentro da
metodologia de análise de bacia, com enfoque paleobiológico o que permitiu uma melhor compreensão dos paleoambientes, em geral interpretados através de dados geológicos ou grupos taxonômicos isolados. Foram inventariados os dados biológicos dos representantes da fauna da Formação Tremembé. A diversidade encontrada foi de 43 espécies de insetos, 13 de mamíferos, 10 de peixes, 8 de crustáceos e de aves, 3 de répteis, 2 de anfíbios, 2 de moluscos, 1 de aracnídeos, anelídeos e poríferos. Realizou-se um levantamento dos trabalhos sobre a flora e a geologia da bacia para interpretação dos paleoambientes. Foi confirmada a existência de um paleolago de grande porte, que não deveria ser oligomítico, pois possuía diversas macrófitas aquáticas e algas, caracterizando uma alta produção. A água apresentava um pH alcalino entre 7 e 9. O lago possuía uma vegetação paludal em seu entorno onde deveriam viver a maioria das espécies de aves e mamíferos. Havia também uma floresta complexa e densa, constituída principalmente de angiospermas, onde animais com alimentação mais seletiva obtinham alimentos. Na região mais alta (seca e fria), prosperavam as diversas gimnospermas identificadas pela palinologia. O clima do vale era úmido, com baixa sazonalidade, à exceção de um forte período de seca registrado no topo da argila bentonítica. Todos os dados encontrados demonstram coerência com a idade Deseadense, final do Oligoceno, início do Mioceno.

In this study, a new evidence of Neogastropods of the family Costellariidae MacDonald, 1860 from the Miocene of Central Paratethys is presented. The finds of fossil shells of the genus Vexillum Röding, 1798 derives from the middle Miocene (Serravallian) marine deposits from the eastern margin of the Vienna Basin (Western Carpathians, Slovakia), which belongs to the north-west Central Paratethys realm. The studied gastropods were discovered at the locality Rohožník – Konopiská, in the basinal pelitic facies and organodetritic corallinacean marls of the Studienka Formation of late Badenian age (Bulimina-Bolivina Biozone). The material studied here includes two new species: Vexillum svagrovskyi sp. nov. and Vexillum pseudoschafferi sp. nov. The affinity and comparison of both species with other similar costellariids from the Neogene of European Eastern Atlantic, Proto-Mediterranean and Paratethyan regions are discussed. From a paleoecological point of view, the results suggest that V. svagrovskyi was adapted to a moderately deep, circalittoral environment with occasional worsening of the paleoecological conditions (low bottom water oxygenation), whereas species V. pseudoschafferi preferred a shallow-water infralittoral environment.

This study develops a new proxy for Quaternary temperature change in tropical Africa through analysis of size variation in East African mole-rat (Tachyoryctes splendens). In modern mole-rats, mandibular alveolar length is unrelated to annual precipitation, precipitation seasonality, temperature seasonality, or primary productivity. However, it is inversely correlated with mean annual temperature, in agreement with Bergmann's rule. This relationship is observed at temperatures below ∼17.3 °C, but not at higher temperatures. We apply these observations to late Quaternary mole-rats from Wakondo (∼100 ka) and Kisaaka (∼50 ka) in the Lake Victoria region and Enkapune ya Muto (EYM; ∼7.2–3.2 ka) in Kenya's central rift. The Lake Victoria mole-rats are larger than expected for populations from warm climates typical of the area today, implying cooler temperatures in the past. The magnitude of temperature decline needed to drive the size shift is substantial (∼4–6 °C), similar in magn...

The study area is located north of the Chubut River, near Las Plumas locality (Chubut province, Argentina). The Danian age of the mi-crofossiliferous Cerro Bororó Formation here studied was established elsewhere. The objective of this contribution is to explain the pa- ...

Jumping bristletails (order Archaeognatha), the basalmost order of extant insects, include some of the earliest fossil records among hexapods, yet their overall geological occurrence remains sparse and has provided little insight into their evolution. The earliest representatives of crown-group bristletails are those in Lebanese amber (Cretaceous), hitherto known only from a single species. Here we significantly expand the known fossil record of Archaeognatha, and from the prolific Lower Cretaceous (Barremian) deposits of Lebanon. One new genus and species, Glaesimeinertellus intermedius gen. et sp. nov., and one new species, Macrop-sontus bachae sp. nov., are described and figured from Hammana amber, whereas one additional Macropsontus species , M. azari sp. nov., and one meinertellid morphotype are described and figured from Al-Rihan amber. The new taxa are compared with their modern and fossil relatives. Collectively , the new taxa render the Archaeognatha fauna from Lebanese amber the earliest with sufficient preservation to provide character data comparable to modern forms, highlighting the considerable morphological conservatism within the order.

The first flowering plant fossils occur as rare, undiverse pollen grains in the Early Cretaceous (Valanginian-Hauterivian). Angiosperms diversified slowly during the Barremian-Aptian but rapidly during the Albian-Cenomanian. By the end of the Cretaceous, at least half of the living angiosperm orders were present, and angiosperms were greater than 70% of terrestrial plant species globally. The rapid diversification of the group, and its dominance in modern vegetation, has led to the idea that the Cretaceous radiation of angiosperms also represents their rise to vegetational dominance. Paleoecological data cast a different light on the Cretaceous radiation of angiosperms. Analyses of sedimentary environments indicate that angiosperms not only originated in unstable habitats but remained centered there through most of the Cretaceous. Morphology of leaves, seeds, and wood is consistent with the status of most Cretaceous angiosperms as herbs to small trees with early successional strategy. The diversification of flowering plants in the Cretaceous represents the evolution of a highly speciose clade of weeds but not necessarily a major change in global vegetation.

This study aims to trace changes in the River Nile flows over the Late Quaternary and is based on palynomorphs which were embedded in the sea floor of the Levantine Basin. The palynomorphs were extracted from two marine sediment cores, which cover the last 86 ka and are located at the two ends of the Levantine Basin: MD-9509, at the southern part of the Levantine Basin, and MD-9501, at its northern part. Core MD-9509 was taken from the Nile cone and is characterized by high sedimentation rates and a good state of palynomorph preservation. The assemblages included palynomorphs which were transported via the Nile headwaters and therefore enabled the reconstruction of the River Nile flows. The results demonstrate that the last glacial period (~75e16 ka) was characterized by a decrease in Nile water discharge and an increase in sediment influx, while opposite trends were observed prior to the last glacial period as well as during the deglaciation and the Holocene. Based on the study of the spores, it is suggested that during the last glacial, the main contributors of freshwater and sediment load to the Eastern Mediterranean Sea were the Blue Nile and the Atbara and only during interglacials was there a more significant contribution of the White Nile. Within the northern core, MD-9501, pollen was preserved only during the formation of sapropels S3 and S1. The comparison of the sapropelic palynological spectra in both core sites clearly indicates that during sapropel deposition, climate conditions were more humid in the Northern Levant, reflecting the north-south regional Mediterranean climatic moisture gradient. Sapropel formation was a result of the intensification of the monsoonal climate system which was most probably related to the maximum insolation values at 65 N, while, currently, the Atlantic is the main influencing climate system in the region. One of the most interesting observations in this study is that during Heinrich Events H2-H6, which originated in the north Atlantic and were identified in MD-9509 based on minimum arboreal pollen percentages, pollen originating from tropical regions was not embedded in the Levantine Basin. These results lend support to the view that episodes of dryness in tropical/sub-tropical Eastern Africa were associated not only with low-latitude climate controls, but also with high-latitude glacial stress.