Palaeogeography, Palaeoclimatology, Palaeoecology

3. Easier access to "fossil gelatin" and quality check by amino acid racemization Publication date: 15 July 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 526 Author(s): Hartwig Elster Abstract Gelatin in fossil bones is the most important source for radiocarbon, stable isotopes, ZooMS (Zooarchaeology by Mass Spectrometry) and Amino Acid Racemization (AAR) studies. The isolation and cleaning of fossil gelatin is a time consuming procedure and can introduce contaminations, which, as a consequence, can produce erroneous results. By synthesizing and optimizing a "Molecularly Imprinted Polymer" (MIP) for gelatin this isolation procedure can be faster and more specific. This first application of MIP on fossil gelatin is described. By optimizing the sample preparation over all steps from getting fossil bone powder (ca. 20 mg), isolating the fossil gelatin by MIP, and analyzing the amino acids, especially the enantiomers of aspartic acid from the fossil gelatin by gas chromatography (GC), results are available within one day. These results include a measure of the quality of the fossil gelatin by the pattern of the single amino acids and the ratios of defined amino acids from the GC chromatogram. At the same time, the AAR can give an estimate of the relative age of the fossil bones.

Composition and structural features of two Permian parareptile (Deltavjatia vjatkensis, Kotelnich Site, Russia) bone fragments and their alteration during fossilisation Publication date: 15 July 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 526 Author(s): Daria Kiseleva, Oleg Shilovsky, Evgeny Shagalov, Anastasia Ryanskaya, Maria Chervyakovskaya, Elizaveta Pankrushina, Nadezhda Cherednichenko Abstract The Kotelnich vertebrate fossil site, one of the richest of the Permian period, is characterised by the excellent preservation of fossil remains due to their burial in a silty anaerobic environment similar to modern peat bogs. The aim of the work is to carry out a comprehensive study of the composition and structure of bone fragments of the Permian parareptile Deltavjatia vjatkensis, as well as that of its embedding rocks, to support further paleoecological and fossilisation reconstructions. Fossil bones and their surrounding strata were investigated using optical and scanning electron microscopy, Raman spectroscopy, X-ray diffraction and inductively coupled plasma mass spectrometry (ICP-MS). The carbonate-rich composition of the sediment was found to favour the preservation of the bone apatite. The mineral phase of the bone tissue corresponds to fluorapatite. Organic matrix vibration bands arising on the Raman spectra correspond to CH vibrations of lipids and proteins and possibly cholesterol. The obtained data indicate a high degree of integrity of both bone mineral phase and its organic proteinaceous residue. White blood cell (WBC)-like structures were detected, which possibly could be interpreted as leukocytes. Elemental mapping of fossil bones was used to reveal element distribution features (uniform or with zones of apparent enrichment-depletion) and secondary mineralisation zones. Ca, P, Mg, Mn and S are uniformly distributed through the bone; conversely, elevated quantities of Fe are assigned to cracks and large pores formed as a consequence of the decomposition of organic materials. As compared to bone apatite, the authigenic calcite filling of bone porosities is significantly depleted in terms of microelements. The apatite rare earth element (REE) composition of bone tissue, which is inherited from seawater, can be used for paleoreconstructions of redox conditions and water composition. La/Sm ratios (0.4–0.5), high Y/Ho ratios, high uranium content and high La/Yb ratios (2–3) in the bone apatite indicate the absence of recrystallisation during the late stages of diagenesis. A positive cerium anomaly detected in the bones indicates the presence of an oxidising and possibly alkaline environment during the early stages of diagenesis in shallow coastal basin of the Kotelnich paleolocality. It is shown that 10 to 20% of REE in bone apatite is derived from seawater absorption (hydrogenous source), with the remainder having been derived from host rock (lithogenic) sources.

Genesis, modification, and preservation of complex Upper Ordovician hardgrounds: Implications for sequence stratigraphy and the Great Ordovician Biodiversification Event Publication date: 15 July 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 526 Author(s): Timothy R. Paton, Carlton E. Brett, George E. Kampouris Abstract Hardgrounds from the Upper Ordovician strata of eastern Laurentia exhibit a wide range of morphologies, though the development of their complex surface topographies remains poorly understood. These early lithified seafloors, which can be laterally very extensive, may provide key information about basin dynamics and global ocean fluctuations. Based on spectacular exposures and newly-excavated material, we examined a suite of hardgrounds from the Upper Ordovician (Katian) of southern Ontario and the Cincinnati Arch region and documented the processes of genesis, development, and modification of simple, complex, and block hardgrounds. In this study, we used extensive field work, petrology, and cathodoluminescence to determine the evolution and shaping of hardgrounds as a result of intense submarine erosion and prolonged exposure of these surfaces and reveal a progression from simple to complex hardgrounds and ultimately to isolated cobble- to boulder-sized block hardgrounds. We survey the distribution of hardgrounds in a sequence stratigraphic framework to determine allocyclic controls on hardground development, highlight the important role that mixed siliciclastic-carbonate environments play in promoting the development of heterogeneous hardground topographies, and analyze the effects of high surface reliefs on local depositional and erosional regimes. In addition, we interpret the impact of increasingly abundant complex hardgrounds throughout the Ordovician on hard-substrate community diversification and their contribution to the Great Ordovician Biodiversification Event. We also discuss time-specific aspects of the Late Ordovician that made it a peak interval of hardground proliferation.

Chronostratigraphic distribution of cetaceans in the Pliocene of Northern Apennines (Italy): palaeoecological implications Publication date: 15 July 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 526 Author(s): Alessandro Freschi, Simone Cau, Paola Monegatti, Marco Roveri Abstract A large number of cetacean fossils have been recovered through the time from the Pliocene deposits in Northern Apennines thrust belt, on both the Padan-Adriatic and the Tyrrhenian side. In this work, the cetaceans of Castell'Arquato Basin (Padan-Adriatic side) have been placed within a high-resolution chronostratigraphic framework available for this area. This results in a better assessment of their evolutionary history and of the palaeoecologic factors controlling their diversity and abundance through the time. Our results document a greater diversity between 3.1 and 2.7 Ma time interval, likely due to the development of eutrophic conditions during precessionally-driven insolation maxima at 400 ka eccentricity maxima, which are recorded in deeper depositional settings by sapropel clusters. Eutrophic conditions kept a complex trophic chain, as currently observed in the Ligurian Sea (Corsican-Ligurian-Provençal Basin), an area characterized also by upwelling. A reduction in both number and ecological diversity of cetacean taxa is observed along the Pliocene-Pleistocene transition; this trend, related to the onset of the Quaternary icehouse conditions, appears in good agreement with the recently recognized extinction event that affecting the marine megafauna at the end of the Pliocene.

Distinguishing core and flank facies based on shell fabrics in Lower Jurassic lithiotid shell beds Publication date: 15 July 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 526 Author(s): Valentina Brandolese, Renato Posenato, James H. Nebelsick, Davide Bassi Abstract Lower Jurassic larger bivalves, mostly represented by the monospecific lithiotid genera Lithiotis, Cochlearites and Lithioperna, formed large shell accumulations in the shallow-water carbonate Tethyan and Panthalassa margins. A quantitative analysis of lithiotid accumulations from the Trento Platform (northern Italy) was carried out in order to distinguish the distribution of autochthonous, parautochthonous and allochthonous lithiotids in the accumulation core and flanks. Various representative accumulations are characterized with respect to systematic content, shell cover, shell density, disarticulation, shell fragmentation and orientation of individual shells. Lithioperna shows a high shell cover within the accumulation core while that of Cochlearites is variable and Lithiotis is rare. All three lithiotids occur in high densities in the accumulation flanks. As expected, autochthonous individuals of all three genera are frequent in the accumulation cores where they are preserved in life position. In the flanks, most bivalves are parautochthonous except for Lithioperna which can grow in life position. All bivalves in allochthonous shell beds are highly fragmented and disarticulated. The studied traits are potentially useful as proxies for distinguishing core or flank facies when the accumulation does not crop out as a whole. Graphical abstract

Carbonate thermoluminescence and its implication for marine productivity change during the Permian-Triassic transition Publication date: 15 July 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 526 Author(s): Zhipu Qiu, Haijun Song, Chaoyong Hu, Paul B. Wignall, Huyue Song Abstract The Permian-Triassic (P-Tr) crisis was the largest mass extinction of the Phanerozoic and eliminated over 90% of marine species. However, the nature of marine productivity changes during the crisis is a matter of on-going debate. Here, thermoluminescence (TL) measurements from 144 bulk carbonate samples from Meishan (South China) show two levels of variation in TL peak intensities at ~270 °C. The first-order variation is characterized by a rapid, nearly three-fold increase. A secondary variation is interpreted to record periodic fluctuations on a Milankovitch scale (~20-kyr rhythm). The periodic variations of TL are negatively correlated with Mn concentrations, suggesting primary productivity is a key factor controlling the TL peak intensity by photo-reduction of particulate Mn in the presence of organic matter. Therefore, the periodic fluctuations of TL were likely controlled by primary productivity changes on orbital timescales. A significant rise of TL peak intensities across the P-Tr boundary represents the rapid increase of dissolved Mn associated with enhanced marine productivity and/or oceanic anoxia.

Population response during an Oceanic Anoxic Event: The case of Posidonotis (Bivalvia) from the Lower Jurassic of the Neuquén Basin, Argentina Publication date: 1 July 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 525 Author(s): Sonia Ros-Franch, Javier Echevarría, Susana E. Damborenea, Miguel O. Manceñido, Hugh C. Jenkyns, Aisha Al-Suwaidi, Stephen P. Hesselbo, Alberto C. Riccardi Abstract Benthonic marine species show a wide range of biological reactions to seawater chemical changes through time, from subtle adjustments to extinction. The Early Toarcian Oceanic Anoxic Event (T-OAE) was recently recognized in the Neuquén Basin, Argentina, confirming its global scope. The event was identified chemostratigraphically on the basis of a relative increase in marine organic carbon and a characteristic negative carbon-isotope excursion (δ13Corg) in bulk rock and fossil wood in the upper Pliensbachian–lower Toarcian interval in the Arroyo Lapa section (Neuquén). Simultaneously with collection of lithological samples, a high-resolution biostratigraphical survey was carried out, and the scarce benthonic fauna was collected in order to check the biotic response to changing marine geochemical conditions. We present here an analysis of size and abundance data from the T-OAE interval in the Neuquén Basin for the dominant bivalve species, the paper-clam Posidonotis cancellata (Leanza), and relate these data to geochemical proxies (%TOC and δ13Corg) obtained at the same locality. The abundance of P. cancellata increased when the rest of the benthos diminished, reaching a maximum at the onset level of the T-OAE, and then decreasing. Size-frequency distributions show a noteworthy lack of juvenile shells. Shell size shows a positive correlation with %TOC in the whole section, though over the T-OAE interval proper, it decreases below the level where the maximum %TOC value is attained and increases above it. Posidonotis cancellata shows features of opportunistic species, such as high tolerance to hypoxia, strong dominance in impoverished environments and a strong dependence on primary productivity, but at the same time had a reproductive strategy more similar to equilibrium species, with relatively low juvenile mortality rates. Several anatomical features suggest adaptation to permanently dysaerobic environments. The species disappeared just before the minimum negative carbon-isotope value was reached; and by the same time the genus became extinct worldwide. Graphical abstract

Recognition of tuffs in the middle-upper Dingqinghu Fm., Lunpola Basin, central Tibetan Plateau: Constraints on stratigraphic age and implications for paleoclimate Publication date: 1 July 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 525 Author(s): Ziqiang Mao, Qingquan Meng, Xiaomin Fang, Tao Zhang, Fuli Wu, Yibo Yang, Weilin Zhang, Jinbo Zan, Mengqi Tan Abstract The Lunpola Basin plays a key role in determining the elevation history of the central Tibetan Plateau, which is closely related to uplift dynamics and paleoclimatic evolution. However, accurate age constraints on the basin stratigraphy reflecting tectonic, paleo-elevation and climate information have long been vigorously debated, mostly due to a lack of absolute age controls. Here, we found two altered tuff layers in the middle-upper Dingqinghu Formation (Fm.) in the basin stratigraphic sequence. Detailed lithological, mineralogical and geochemical analyses of the tuffs indicate that they came from trachyandesite and identify analcime as the typical alteration mineral, suggesting primary deposition. LA-ICP-MS zircon U-Pb dating of the tuffs yields concordant ages of 20.6 ± 0.1 Ma and 20.7 ± 0.1 Ma, indicating that the end of the Dingqinghu Fm., i.e., the Lunpola stratigraphic sequence, and the uplift of the plateau to its current high elevations occurred much later than previously estimated. The contemporaneous thick black oil shales in the Lunpola deep lake and biocoenosis together suggest that the climate was humid and warm during this period.

Paleoceanographic changes across the Latest Danian Event in the South Atlantic Ocean and planktic foraminiferal response Publication date: 1 July 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 525 Author(s): Sofie Jehle, André Bornemann, Anna Friederike Lägel, Arne Deprez, Robert P. Speijer Abstract A number of short warming events occurred during Paleocene and Eocene, of which the "Paleocene-Eocene Thermal Maximum" (PETM, 56 Ma) is the most severe and most investigated event. The less known "Latest Danian Event" (LDE) at 62.2 Ma represents a 200 ky-lasting warming phase, superimposed on a long-term cooling trend after the Early Paleocene. South Atlantic ODP Site 1262 data, covering ~1 myr, indicate a warming of the entire water column by 1.5–2.6 °C, accompanying a prominent negative carbon isotope excursion (~0.9–1.1‰) and a long-term re-organization of the planktic foraminiferal fauna associated with the LDE. This study unravels a different paleoceanographic evolution of the upper ocean structure compared to results from Pacific ODP Site 1210. Unlike the Pacific, the Atlantic site lacks an apparent change of stratification as well as an overall dominance of thermocline dwelling planktic foraminifera species and a low abundance of surface dwelling photosymbiotic foraminifera. Within the LDE, indications for a slightly enhanced stratification of the upper water column and transient warming were indicated when surface dwelling planktic foraminifera became temporarily more abundant. The long-term evolution in planktic foraminifera with the disappearance of Praemurica at the LDE onset and a contemporaneous rise in Morozovella is similar to the trends reported from Shatsky Rise ODP Site 1210.

Early diversification of Ordovician chitinozoans on Baltica: New data from the Jägala waterfall section, northern Estonia Publication date: 1 July 2019 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 525 Author(s): Jaak Nõlvak, Yan Liang, Olle Hints Abstract Chitinozoans are a group of biostratigraphically valuable microfossils which appeared in the Tremadocian and diversified during the rest of the Great Ordovician Biodiversification Event, to become extinct in the Devonian. The early diversification of chitinozoans on the Baltica palaeocontinent has remained poorly known due to preservation and collecting bias. In this study we document the distribution of chitinozoans through the upper Tremadocian to lower Darriwilian strata in the Jägala waterfall section from northern Estonia, in order to better understand the regional diversity patterns and biogeographic links. Fifty samples were studied from the 7.5 m succession of sandstones, marls and carbonates revealing 47 chitinozoan species and 11 genera. The lowermost productive samples, attributed to the late Tremadocian, represent the earliest rich chitinozoan fauna from Baltica. Combined with previous reports this shows a diversity peak in the Tremadocian with balanced total diversity reaching 17, possibly followed by a decline in the Floian and then a rather gradual increase through the Dapingian and early Darriwilian. The new diversity curve shows more than three times higher values for the Tremadocian and Dapingian than indicated in previous studies, and thus less abrupt radiation in the Darriwilian. The Jägala section provided also new data on the regional biozonal species Conochitina cucumis and Cyathochitina regnelli, which characterize the middle and upper Volkhov and lower Kunda regional stages, respectively. Several other biostratigraphically significant taxa typical of other regions were recovered from the Jägala section, including Conochitina decipiens and Desmochitina bulla. A new short-ranging species Laufeldochitina toilaensis sp. nov. is introduced, having potential to become an index species for middle Dapingian strata. The early Darriwilian assemblage from Jägala includes Rhabdochitina sp. A with up to 2.7 mm long vesicle, making it the largest chitinozoan ever reported.