Abstract An excavation of an Early Iron Age village near Aalborg in Denmark uncovered the jaws and skull fragments from a small mammal that were morphologically identified to the genus Crocidura ...(white‐toothed shrews). Three Crocidura species are known from prehistoric continental Europe but none of them are distributed in Scandinavia, which is why this surprising finding warranted further analyses. The bone was radiocarbon‐dated to 2840–2750 calibrated years before present (cal. BP), corresponding to the Late Bronze Age and hence earlier than the Iron Age archeological context in which it was found. Using highly optimized ancient DNA protocols, we extracted DNA from one tooth and shotgun‐sequenced the sample to reconstruct a near‐complete mitochondrial reference genome (17,317 bp, 32.6× coverage). Phylogenetic analyses determined this specimen as a bicolored shrew ( Crocidura leucodon ) but with a phylogenetic position basal to the clade of known sequences from this species. The confirmation of Crocidura presence in Denmark by the Late Bronze Age sheds new light on the prehistoric natural history of Scandinavia. We discuss the implications of this finding from both zoo‐archeological and ecological perspectives. Furthermore, the mitochondrial genome reconstructed in this study offers a valuable resource for future research exploring the genetic makeup and evolutionary history of Eurasian shrew populations.
During the Pleistocene the Great Basin was filled by endorheic lakes that receded greatly during the Holocene. Several proxy records provide extensive evidence that the basin has gone through periods ...of amelioration from low precipitation followed by a return to dry conditions through the Holocene. Relative to the Pleistocene/Holocene transition and middle Holocene, aside from the Medieval Climate Anomaly, study of the late Holocene has received less attention. In recent years evidence has emerged for a ca. millennial length drought termed the Late Holocene Dry Period (LHDP), between about 2800 and 1800 years ago. The LHDP has been proposed to follow a dipole climatic pattern associated with changes in precipitation linked to the Southern Oscillation Index (SOI) and described as a dry southwest and wet northwest in the United States. Here I present a 4000-year pollen record from northwestern Nevada, investigating the potential for the Late Holocene Dry Period to conform to the modeled dipole pattern in this part of the region. This site is located near a zone of ambiguity between wet and dry conditions in order to identify more definitively where the modeled dipole pattern is centered.
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The typical mammalian neck consisting of seven cervical vertebrae (C1–C7) was established by the Late Permian in the cynodont forerunners of modern mammals. This structure is ...precisely adapted to facilitate movements of the head during feeding, locomotion, predator evasion, and social interactions. Eutheria, the clade including crown placentals, has a fossil record extending back more than 125 million years revealing significant morphological diversification in the Mesozoic. Yet very little is known concerning the early evolution of eutherian cervical morphology and its functional adaptations. A specimen of Zalambdalestes lechei from the Late Cretaceous of Mongolia boasts exceptional preservation of an almost complete series of cervical vertebrae (C2–C7) revealing a highly modified axis (C2). The significance of this cervical morphology is explored utilizing an integrated approach combining comparative anatomical examination across mammals, muscle reconstruction, geometric morphometrics and virtual range of motion analysis. We compared the shape of the axis in Zalambdalestes to a dataset of 88 mammalian species (monotremes, marsupials, and placentals) using three-dimensional landmark analysis. The results indicate that the unique axis morphology of Zalambdalestes has no close analog among living mammals. Virtual range of motion analysis of the neck strongly implies Zalambdalestes was capable of exerting very forceful head movements and had a high degree of ventral flexion for an animal its size. These findings reveal unexpected complexity in the early evolution of the eutherian cervical morphology and suggest a feeding behavior similar to insectivores specialized in vermivory and defensive behaviors in Zalambdalestes akin to modern spiniferous mammals.
Bu çalışma, İç Anadolu'nun önemli havzalarından biri olan Çankırı-Çorum havzasında, Orta Eosen yaşlı Kocaçay Formasyonu'na ait birimlerin Mollusk (Gastropoda ve Bivalvia) faunasının sistematiğini ve ...biyostratigrafisini ortaya koymayı amaçlamaktadır. Bu kapsamda Çorum Bayat ve Sungurlu, Kırıkkale Sulakyurt ve Kırşehir Çiçekdağı olmak üzere dört alt alanda arazi çalışmaları gerçekleştirilmiş, her bir alt alanda en az ikişer olmak üzere toplam 11 adet ölçülü stratigrafik kesit alınmıştır. Formasyonda Mollusca şubesine ait 2 cins ve 59 tür olmak üzere toplam 61 adet fosilin detaylı sistematik tanımlaması yapılmıştır. Tanımlanan Gastropoda sınıfına ait 1 cins (Turritella sp.) ve 34 adet tür; Tectus mitratus, Velates perversus, Jponsia cuvieri, Tympanotonos (Eutympanotonos) conulus, Turritella (Haustator) imbricataria, Mesalia fasciata, Campanile giganteum, C. incomptum, C. leymeriei, C. cf. parisiense, Cernina sphaerica, Amauropsella spirata, Cepatia cepacea, Euspirocrommium oweni, Globularia sigaretina, G. vulcani, Pachycrommium scalariformis, Gisortia cf. murchisoni, Sinum karamassensis, Euspira achatensis, Tornus (Adeorbis) tenuistriatus, Seraphs olivaceus, Seraphs sopitus, Xenophora cf. agglutinans, X.cf. patellata, Amaea (Acrilla) essomiensis, Clavilithes (Clavellofusus) clavellatus, C.cf. maximus, C.pinus, Fusinus zafiranboliensis, Gibberula ovulata, Eoconus diversiformis, Syrnola conulus ile Bivalvia sınıfına ait 1 cins (Nucula sp.) ve 25 adet tür Ostrea multicostata, O. roncaensis, Pycnodonte brongniarti, P. cymbiola, P. gigantica, Pecten tchihatcheffi, Chlamys subdiscors, Palliolum solea, Mimachlamys plebeia, Anomia tenuistriata, Spondylus asiaticus, S. eocenus, S. radula, Lima cf. spatulata, Miltha gigantea, Saxolucina saxorum, Crassatella (Pachythaerus) gibbosula, C. gigantica, C. tumida, C. subtumida, Venericar planicosta, Trapezium parisiensis, Cardium nummuliticum, Trachycardium gratum, Tellina cf. granconensistürleri saptanmıştır.Faunanın paleocoğrafik ve stratigrafik yayılımı incelendiğinde Kocaçay Formasyonu'nun Lütesiyen-Bartoniyen çağlarında çökeliminin gerçekleştiği sonucuna varılmıştır. Tanımlanan faunanın paleoekolojik özellikleri formasyonun kuzey kesimde deltaik sığ denizel; ortada lagüner, sığ denizel ve güneyde sığ denizel özellikte olduğu tespit edilmiştir. Çalışılan alanlarda Ostrea roncaensis, Velates perversus, Miltha gigantea ve Pycnodonte gigantica Bolluk biyozonları ile Ostrea roncaensis ve Campanile incomptum, Pycnodonte gigantica ve Crassatella gigantica, Amauropsella spirata ve Globularia sigaretinaTopluluk biyozonları tanımlanmıştır.
Extensive research has been conducted at Lake Tanganyika with the aim of understanding its vulnerability to both warming climate and fishing pressure. However, much of this work has been restricted ...to the more accessible northern basin. Studies from a limited geographic region of the lake are insufficient to explain whole-lake dynamics of the world’s longest lake, that stretches ~670 km (3.4–8.9°S), across several bathymetric basins. While strong evidence suggests that lake warming has played a critical role in decreasing fish abundance in Lake Tanganyika, limnological changes associated with warming have not been shown to be a lake- wide phenomenon. Paleolimnological methods can be used to compare the trajectories of environmental change among regions. This study examines southern Lake Tanganyika to provide insight into whether paleo-environmental changes observed in the northern basin are, in fact, representative of lake-wide phenomena, and in the process help to improve fisheries management. Here, we present new paleoecological analyses from two deep-water sediment cores from the southern basin of Lake Tanganyika. Fossil diatom assemblages show a shift in dominance towards lightly-silicified taxa (Nitzschia spp.) after ~200 YBP, with fewer heavily- silicified taxa. These results are indicative of a relative reduction in convective lake mixing but are not always coincident with temperature trends, suggesting local windiness may also be important for stratification history. A general decrease in diatom concentration in the late Holocene is probably reflective of a decrease in net primary productivity in response to the inferred decrease in convective mixing. In contrast, the episodic presence of deep benthic invertebrates (ostracodes and molluscs) at these deep sites, which also co-occur with high Mn, indicates infrequent and short-lived pulses of much deeper ventilation of the southern basin than has been recognized previously. The coincident presence of periphytic diatom species and benthic invertebrates during periods of strong stratification suggests that the lake bottom was periodically ventilated by descending denser (cooler or more sediment-rich) influent waters along the steep slopes of the coastline. Fish fossil abundance also is correlated with the dominance of heavily-silicified diatom taxa, which itself requires stronger wave activity and upwelling of deep, nutrient-rich water. Thus, changes in lake productivity in the southern basin appear to be climate-mediated, but in ways not previously documented in the northern part of the lake.
This work aims to study the preserved communities in rocks from the Cambrian-Ordovician, exposed west of the Arivechi, Sonora town in northwest Mexico. A total of 860 individuals from 70 species are ...analyzed, belonging to four Cambrian units (El Gavilán, El Mogallón, Milpillas, and La Huerta formations) and one Ordovician unit (El Santísimo formation), the latter one divided into three members.
After a petrographic and paleoecological analysis, it is concluded that the El Gavilán and El Mogallón formations are characterized by deposits of an open and external platform dominated by epifaunal suspension feeders. The Milpillas formation is distinguished by rocks deposited in an open and restricted internal platform environment, where epifaunal organisms and suspension feeders prevail. The La Huerta formation is notable for its high content of brachiopods, epifaunal organisms, and suspension feeders. The first two members of the El Santísimo formation show a significant environmental change, as they are deposits from a deep-water cratonic basin.
The change in biota includes planktonic organisms and suspension feeders. Finally, the upper member of the El Santísimo formation contains biota characteristics of a slope and a shallow marine platform environment near the coastline, with abundant nektobenthic organism life.
•A paleoecological study is performed for the Cambrian-Ordovician of Arivechi, Sonora.•Cambrian-Ordovician marine communities are dominated by sessile organisms.•Faunal assemblage has affinity with Laurentia.
Cultural eutrophication, the addition of excess nutrients to an aquatic system, is a significant water quality concern that often promotes excess algal growth and deep-water oxygen depletion. ...Deep-water oxygen also influences internal nutrient loading and is an important parameter used to assess cold-water fish habitat, though long-term data are often unavailable. Chironomid (Diptera: Chironomidae) assemblages have been shown to change with deep-water oxygen concentrations and can therefore be used to reconstruct these missing data sets. This thesis used paleolimnological techniques to analyze inferred whole-lake primary production, sedimentary chironomid assemblages, and inferred volume-weighted hypolimnetic oxygen to determine how cold-water fish habitat has changed through time. I will also examine whether biological recovery after nutrient-targeting remediation was introduced was evident in sedimentary chironomid assemblages. I focused on two lakes with increasing inferred whole-lake primary production (Muskrat and Stoco lakes, Ontario) and one lake with decreasing inferred primary production (Lac Duhamel, near Mont Tremblant, Québec) over time. The majority of change in response to elevated inferred whole-lake primary production is evident in littoral taxa and head capsule concentrations, though oxy-conforming profundal taxa (e.g. Micropsectra) did respond to increased whole-lake primary production. Overall, deep-water oxygen recovery after nutrient-targeting remediation was not evident in the sedimentary chironomid assemblages and that there were generally only subtle responses to elevated whole-lake primary production. Many of our lakes had historically low deep-water oxygen concentrations that were suboptimal for cold-water fish throughout their sedimentary records, with two lakes experiencing modest declines after there were increases in whole-lake primary production. These paleolimnological data can be used to set realistic mitigation targets for deep-water oxygen conditions and cold-water fish habitat restoration.
The city of Tikal, in northeastern Guatemala, was a major Maya polity for many centuries until the site core was abandoned within a 50-year span during the Terminal Classic period (A.D. 850 – 950). ...The inhabitants relied upon freshwater stored in their reservoirs, especially during the dry seasons. Diatoms, because of their well-preserved siliceous frustule, can be used as a proxy to determine water quality through time. Our results indicate that the water of at least one of their major reservoirs was contaminated during the Late Classic period, just prior to the abandonment of the site core of the city. Here we present a chronological change of Tikal reservoir water quality from Early Classic through Post Classic times as indicated by diatom content in radiocarbon dated layers of reservoir sediment pits. Within the Early Classic Period and Late Classic Period contexts, Lindavia radiosa and L. bodanica were the dominant diatom species, suggesting that water quality was within today’s Environmental Protection Agency’s (EPA) standards for safe drinking water. When we examine the end of the Late Classic period data, however, Cyclotella meneghiniana in the Palace Reservoir indicated the water developed eutrophic characteristics. Analysis of Tikal’s Palace reservoir sediment indicates deteriorating water quality and severe eutrophication near the end of the Maya occupation of the city.
Fire is an important earth-system process, which is impacted by climate, and in turn shapes plant communities and drives biogeochemical cycling. Long-term perspectives on fire history are valuable in ...understanding the historical role of fire in maintaining plant communities, and paleoenvironmental methods are a primary source for this information. Great Lakes barren communities, characterized by pines and other fire-adapted plants growing in sandy, well-drained soils, are a regionally unique ecosystem type that is likely fire dependent. However, long-term perspectives on fire history are needed to inform management. In this study, I quantify multiple size-fractions of charcoal throughout a peat core to compare burning at different spatial-scales through time, comparing and contrasting fire history in the Great Lakes barren community with that of the broader island and regional mixed-deciduous forest. I compare these fire history records with a surface-moisture reconstruction developed through testate amoeba analyses to assess hydrological controls on burning, and use my data to discuss the utility of peatland fire history records and make brief management recommendations. Macroscopic charcoal influx was high throughout most of the ~6000-year record, with particularly high levels indicating periods of increased local burning 4.1-3.6 ka, 2.6-2.1 ka, and over the last ~400 years prior to fire suppression. Microscopic charcoal influx showed little correlation with the macroscopic record (r=0.17), indicating mostly distinct signals from regional and local fires respectively. However, nine instances of simultaneous local and regional fire episodes were identified, likely representing occurrences of major, widespread fires. All simultaneous regional and local fire events occurred when bog moisture was drier than average, and regional fire history was weakly correlated with bog hydrology for the past 2500 years. Results indicate that the sand barren landscape has a history of persistent local burning with an average fire return interval of about 55 years, and fire history was unrelated to local bog hydrology, although increased large fires during the Medieval Climate Anomaly and decrease large fires during the LIA suggest a possible relationship with temperature or seasonal moisture changes. Controlled burning of Great Lakes barren communities that is broadly consistent with the observed historical fire frequency of the past 400 years is most likely to maintain this rare and unique community. Finally, my results highlight the value of peatland records of fire history, which have been underutilized in paleoenvironmental studies even though these depositional systems provide some advantages over lakes.
A paleoecological evaluation was undertaken on an exposure of the Comanche Peak Limestone Formation in Oglesby, Texas. The Comanche Peak Limestone Formation is part of the Early Cretaceous-aged ...Fredericksburg Group, a sequence of carbonate rocks recording the encroachment of the Western Interior Seaway during the Middle Albian. Named and described by R. T. Hill in the late 1800’s, the Comanche Peak Limestone Formation has not gathered as many studies as the overlying Edwards Limestone Formation. The Edwards Limestone Formation is dominated by rudistid grainstone (Dunham, 1962) and contains natural gas and petroleum reservoirs, in addition to being a major aquifer of Texas. While the Comanche Peak Limestone Formation lacks these economic resources, it has a scientifically valuable record of the Early Cretaceous paleoecology of Central Texas. The Paleoecological study found that the site was dominated by bivalve and gastropod groups, consistent with carbonate shelf environments. Interpretations of the fossil data utilizing PAST software suggests evidence of at least 4 distinct paleoenvironments and associated faunal assemblages. Analyses of these paleoenvironments were complicated by the coarse recrystallization of the Comanche Peak fauna and the diminishing quantity of fossils moving up through the outcrop, and reconstructions are tenuous without further study.
