Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Douaa Fathy, Michael Wagreich, Susanne Gier, Ramadan S.A. Mohamed, Rafat Zaki, Mohamed M. El Nady A comprehensive set of organic and inorganic geochemical proxies, clay mineralogy, and molecular fossils are presented from two biostratigraphically well-dated oil shale horizons of Egypt, within the Upper Cretaceous Duwi and Dakhla formations. The studied oil shales were deposited within intracratonic sedimentary basins in a broad northern African epeiric sea. Calcareous nannofossil biostratigraphy indicates that the oil shales range from early to late Maastrichtian in age, covering nannofossil zones UC18, UC19, and UC20. The oil shales contain smectite and kaolinite as the main clay minerals that formed by weathering of precursor basement rocks. The relative abundances of clay minerals and several geochemical proxies (e.g. C-value, CIA, Ga/Rb, Rb/Sr and Sr/Cu), along with the occurrence of warm-water nannofossil taxa, demonstrate that the Maastrichtian oil shales accumulated under a warm, arid to humid greenhouse climate during a general Maastrichtian cooling trend. This episode of oil shale deposition in Egypt coincided with the first potential imprint of the global warming, that has been recorded during early-to-late Maastrichtian times (~70.6–67.7 Ma). Elevated eolian terrigenous input was recorded within the Duwi Formation oil shales, shown by high Ti/Al, Si/Al, Zr/Al and low La/Lu ratios. The Duwi Formation environment was characterized by enhanced salinity and a stratified water column, compared to that of the Dakhla Formation, shown by elevated values of the gammacerane index, tetracyclic terpane, β‑carotene and Sr/Ba ratio. The CaCO 3 content and carbonate/siliciclastic ratio indicate that the Dakhla Formation oil shales were deposited during a relative sea-level rise in a deeper marine setting than the Duwi Formation oil shales. The data further imply a wind-driven upwelling scenario of nutrient input s that simulated primary production and increased organic matter fluxes. Thus, paleoclimate and paleoceanography had a considerable impact on organic matter enrichment.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Maria Rivera-Araya, Suzanne Pilaar Birch Oxygen and carbon isotopes from herbivore teeth have previously been used as paleoenvironmental proxies. However, their use in white-tailed deer ( Odocoileus virginianus ) remains rare. Here, we present the results of analysis of sequential sub-samples from second and third molars of wild and non-wild deer from Georgia, United States in order to assess their application in humid subtropical climates. In wild deer, enamel carbonate δ 18 O corresponds broadly to the recorded precipitation δ 18 O over the 10-month period of tooth formation, capturing the rainfall seasonality across the physiogeographic regions of the state. Non-wild deer show significantly lower values compared to both measured and modeled δ 18 O precipitation. While δ 13 C in tooth enamel carbonate appears to reflect diet, it does not reflect seasonality in either population. The δ 13 C and δ 15 N from bone collagen values suggest that diet and source of drinking water influence the potential of white tailed deer tooth enamel carbonate to record the δ 18 O seasonality in the study area; therefore, special attention on the provenance of deer are necessary for obtaining accurate paleoclimate reconstruction.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Elver Luiz Mayer, Leonardo Kerber, Ana Maria Ribeiro, Alex Hubbe A recurrent aspect of the fossil record is the observation of a disproportionate number of specimens or individuals of a single taxon in some deposits, which is stated as dominance. Commonly, the dominance is explained as the result of catastrophic or short-term mass death events or are proxies for palaeoecological inferences regarding gregariousness. However, taphonomic, stratigraphic and chronologic analyses of fossiliferous deposits have shown that this is not always true. To contribute to the study of dominance in fossil assemblages, we describe a probable Quaternary skeletal accumulation dominated by the extant gregarious rock-dwelling rodent Kerodon rupestris recovered from Sumidouro do Sansão, a 65 m deep pitfall cave in northeast Brazil, and discuss the palaeoecological implications of our findings. We provide taxonomic identification, taphonomic analyses, and chronological assessment. Besides K. rupestris (minimum number of individuals, MNI = 35), we recorded three taxonomic groups, that are the ground sloth Catonyx cuvieri (MNI = 1), the anteater Tamandua tetradactyla (MNI = 1), and the cougar Puma concolor (MNI = 1). The taphonomic analysis of the K. rupestris remains supports the idea that entrapment of individuals was the main process of bone accumulation and that the death of cave inhabitants followed by short transport to the main hall possibly occurred. Kerodon rupestris remains persisted on the surface of the cave deposit for different time spans and were exposed to fragmentation, weathering, invertebrate boring and encrustation inside the cave environment. Direct dating suggests differences in the ages obtained and intermittent deposition of the individuals inside the cave. It highlights the influence of taphonomic controls on gregarious taxa, such as K. rupestris , towards dominating attritional time-averaged assemblages. Furthermore, it demonstrates that such assemblages do not necessarily support inferences about single event mortality and gregariousness of the dominant taxon. Graphical abstract

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Dan C. Jipa

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Shan Chang, Sébastien Clausen, Lei Zhang, Qinglai Feng, Michael Steiner, David J. Bottjer, Yan Zhang, Min Shi Lower Cambrian assemblages of phosphatic and chitinous tubular fossils of probable cnidarian affinities were recovered from the Yanjiahe, Shuijingtuo and Shipai formations in the Three Gorges area, South China. Terreneuvian Cambrorhytium cf. C . major co-occur with an unnamed taxon in the Yanjiahe Formation. They can be compared with specimens from the Ediacaran Miaohe Fauna in the Three Gorges area. The most abundant and diversified cnidarian assemblages, including Cambrorhytium gracilis n. sp., Cambrorhytium cf. major , Cambrorhytium minor , Sphenothallus songlinensis , Sphenothallus taijiangensis ?, Sphenothallus kozaki , ? Sphenothallus sp., ? Byronia sp., and ? Mackenzia sp. are reported from the overlying, Cambrian Stage 3–4, Shuijingtuo and Shipai formations. These new fossils show previously unknown evidence for cnidarian affinities, such as an attachment disk, clonal clusters and probable budding structures. These diversified assemblages of probable cnidarian fossils further fill major gaps in the Cambrian record of stem metazoans and document associated early evolutionary patterns. In addition, our discovery suggests that along with sponges, these tubular fossils represent another important component of benthic ecosystems that colonized often dysoxic, deep-settings during the Cambrian explosion. The observed increases of average body-size and biomineralization among these probable cnidarians are tentatively linked to oxygenation of deep oceanic settings and appearance of predatory pressure during the Ediacaran–Cambrian transition, respectively.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Beñat Intxauspe-Zubiaurre, Naroa Martínez-Braceras, Aitor Payros, Silvia Ortiz, Jaume Dinarès-Turell, José-Abel Flores The last hyperthermal event in the Eocene, the Late Lutetian Thermal Maximum or Chron C19r event, took place at ~41.5 Ma, during a long-term global cooling phase which occurred between the warm Early Eocene Climatic Optimum and the icehouse Oligocene Epoch. This paleoclimatic event was first identified in the Equatorial Atlantic Ocean Drilling Program (ODP) Site 1260 as an abrupt peak in bulk Fe content and a short-lived decline in stable isotopes (δ 13 C, δ 18 O) and carbonate content. Additional studies have recently been carried from the Southern Atlantic ODP sites 702 and 1263. However, many issues were not addressed at these deep-sea sites and no land-based record of the event had been studied. Therefore, the beach cliff at Cape Oyambre (N Spain) was analyzed with the aim of identifying the C19r event and investigating its paleoenvironmental impact. Using magnetostratigraphic and biostratigraphic information, the astronomically tuned cyclo-stratigraphic record from Oyambre was accurately correlated with ODP Site 1260. This, combined with stable isotope data, allowed identification of the event in a conspicuous dark marl bed. Given that the associated negative carbon isotope excursion extends for 2/3 of a precession-driven hemicouplet, a 7–11 kyr duration was estimated, which agrees with recent estimates from the Atlantic deep-sea sites. Exceptional insolation conditions were found to have accelerated the hydrological cycle, increasing rainfall and runoff on land and terrestrial sediment input to the sea, which resulted in relatively low carbonate content in the deep-sea sediments. The terrestrial input also caused seawater eutrophication and freshening, leading to low δ 13 C and δ 18 O values, increased abundance of autochthonous and reworked calcareous nannofossil taxa, peaks in the abundance of opportunistic Reticulofenestra 〈5 μm and opportunistic benthic foraminifera, and a reduction in the abundance of the oligotrophic calcareous nannofossil Zygrhablithus bijugatus . However, neither intensified carbon-gas driven greenhouse effect nor warming over and above natural fluctuations could be demonstrated from the Oyambre data.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Kaarel Mänd, Karlis Muehlenbachs, Ryan C. McKellar, Alexander P. Wolfe, Kurt O. Konhauser Ambers—fossilized plant resins—are a rich and unique source of paleoecological data due to their ability to preserve soft body fossils. However, interpretations concerning their environmental context are often hampered by uncertainties in the relationship between assemblages of inclusions and geological context, particularly in the case of secondarily redeposited ambers such as those from the Paleogene of Central Europe. Here we use stable carbon and hydrogen isotope analyses, as well as FTIR spectroscopy, from the northwestern Ukrainian Rovno amber deposit, to provide independent constraints on the geographic and temporal origins of Rovno amber. These analyses address the relationship between the Rovno and Baltic amber deposits as well as German Bitterfeld amber—a subject of considerable debate regarding their provenance. Rovno amber has a δ 13 C signature of −23.3 ± 0.9‰, similar to both Baltic and Bitterfeld ambers. Since there is a secular decreasing δ 13 C trend among amber deposits since the Early Eocene, a roughly contemporaneous origin of these deposits in the Eocene can be deduced. However, Rovno amber displays a δ 2 H signature of −258 ± 9‰, 19‰ more positive than Baltic amber, and directly comparable to Bitterfeld amber. This difference relates to precipitation sources and mean annual temperatures of the amber source regions, and suggests a much more southerly origin of Rovno amber relative to Baltic amber. FTIR spectra of each of these ambers are nearly identical and suggest that resin-producing trees were from similar families, despite contrasting source regions. Thus, we provide the first clear geochemical evidence for the distinct origin of Rovno and Baltic amber deposits, with implications for paleoecological studies involving inclusions from these deposits, and for determining the provenance of archaeological amber finds.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Xinying Zhou, Jilong Yang, Shiqi Wang, Guoqiao Xiao, Keliang Zhao, Yan Zheng, Hui Shen, Xiaoqiang Li We present new pollen data from a drilling core from the North China Plain which illustrate the nature of vegetation evolution in the temperate zone of Asia during an interval containing the Mid-Pleistocene Transition (MPT), ~1.2–0.7 Ma. Results show that, from 1.7–1.2 Ma, closed needle-leaved and broadleaved mixed forest predominated. The most important vegetation change event occurred at 1.2 Ma when there was a decline in coniferous forest and a significant increase in Artemisia , Chenopodiaceae and Poaceae grassland. There was a continued degradation of the regional forest vegetation and its replacement by woody grassland about 0.7 Ma. Patterns of vegetation change correlate closely with the key climate fluctuations of the MPT and coincide with major turnover events of large mammalian fauna (>10 kg) in China. In particular, >50% of large mammalian species became extinct in the course of the forest decline; however, they were replaced by new mammalian species after 0.7 Ma. Comparison of the vegetation and faunal records indicates that the process of forest replacement by grassland in the northern temperate zone during the MPT was associated with an acceleration of the rate of turnover of the large mammalian fauna, in terms of extinction and speciation.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Yuqing Wang, Ayano Ito, Yong-Jiang Huang, Tohru Fukushima, Nobuhiko Wakamatsu, Arata Momohara Fossil plant assemblages play a critical role in paleoenvironment estimation, especially for the Cenozoic. However, the extent that the fossil assemblage reflects the source forest is difficult to estimate. The comparison between modern assemblages and their subfossil assemblages shows a significant difference, indicating that the transportation of plant organs can affect the accuracy of paleoenvironment analysis. In this study, we aim to detect leaf transport based on stomatal frequency (stomatal index and stomatal density) variation of 30 fossilized Fagus crenata leaves from the Sayama Formation (1.54–1.66 Ma). We distinguished the sun and shade morphotype of fossil leaves by using undulation index and calculated stomatal frequency variation of only sun fossil leaves. Considering the stomatal index variation of fossil Fagus crenata leaves, the paleo- p CO 2 variation in a warm period between 1.54 Ma and 1.66 Ma was estimated as ca. 35.0 to 39.6 pa. Based on this paleo- p CO 2 variation, altitudinal transportation range of the Early Pleistocene fossil Fagus crenata leaves was estimated at over 1000 m. We presume that leaves of Fagus crenata in the fossil assemblage possibly had come from a wide range of altitudes near the fossil site during the Early Pleistocene. This provides an example of altitudinal transportation of plants before their deposition, which suggests a consideration when reconstructing the palaeovegetation and palaeoclimate from fossil assemblages.