Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Elsbeth E. van Soelen, Wolfram M. Kürschner The Late Permian extinction interval is in many marine locations characterized by the development of anoxic conditions. The Finnmark Platform is one of few exceptions, as sedimentological and palynofacies evidence indicate oxygenated conditions throughout the event. Changes in acritarch assemblages and morphology were studied in order to better understand the link between acritarchs and environmental conditions. The main taxa are of Micrhystridium , Baltisphaeridium and leiospheres, while Veryhachium and the prasinophytes Cymatiosphaera and Tasmanites were present in low abundances. Increased concentrations of acritarchs, particularly Micrhystridium , show that the environmental changes at the start of the extinction event may have resulted in enhanced marine productivity. A shift from Micrhystridium/Baltisphaeridium dominance before and during the extinction event, to leiosphere-dominance after the extinction event, indicates a shift towards a more inshore environment. The new data are compared with published Late Permian acritarch records from East Greenland, China and Pakistan. A striking difference between the East Greenland and Finnmark Platform, which are both expanded Upper Permian/Lower Triassic sections, is that the acritarch record from Greenland shows a strong decrease in process length of the acritarch Micrhystridium . Together with a change in the acritarch assemblage, this change in morphology was interpreted to represent a decrease in salinity at the site, resulting from increased run-off. The differences between the East Greenland and the Finnmark records are likely due to their palaeogeographical settings, as the East Greenland section was located in a narrow and elongated basin which was likely more sensitive to evaporation and run-off changes than the Finnmark Platform.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Gildas Merceron, Marc Colyn, Denis Geraads Today, the family Giraffidae is restricted to two genera endemic to the African continent, Okapia and Giraffa , but, with over ten genera and dozens of species, it was far more diverse in the Old World during the late Miocene. We attempt to describe here how several species may have shared feeding resources in the Eastern Mediterranean. Dietary preferences were explored by means of Dental Microwear Textural Analysis in combination with estimation of body mass and the maximum height at which the various species were able to browse. One of our main results concerns the modern okapi, Okapia johnstoni . It is a forest dweller usually regarded as a browser, but we show that it might also forage on tough plants, possibly herbaceous monocots. Such feeding habits including portions of herbaceous monocotyledons were also found for some extinct species, especially the genera Samotherium and Palaeotragus . Palaeogiraffa shows a contrasted pattern: the specimens of P. pamiri from a site in Thrace were leaf-dominant browsers whereas those belonging to P. major and P. macedoniae from the Axios valley in Greece ingested herbaceous monocotyledons. Helladotherium duvernoyi , the only sivatheriine analyzed here is described as a leaf-dominant browser. The giraffine Bohlinia attica also falls within the leaf-dominant browser category but could browse on higher foliages than H. duvernoyi . On the whole, the reconstructed diets confirm the relationship between more grazing habits and smaller premolars, but not with higher dental crown height.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Tian Ying, David Shaw, Simon Schneider Sediments of the long-lived Lake Nanning in southern China (Guangxi Province) have yielded rich and diversified fossil biota of Oligocene age. The history of research on these fossils is documented herein, and revised lists of the flora and fauna recorded from Lake Nanning are provided. Based on newly collected data, the mollusc fauna and palynology of the lake sediments are assessed. Gastropods (Viviparidae, Stenothyridae), bivalves (Unionidae), ostracods and fish have successfully radiated in Lake Nanning, and developed a variety of endemic species. Shell thickening, spines, carinae, nodes and restricted apertures in bivalves and gastropods are interpreted as armour to prevent predation by giant shell crushing carp. Four different, successive macro-mollusc associations are documented, and can likely be used for relative dating of the lake sediments. Palynomorph assemblages from different lake stages are dominated by cool temperate conifer pollen and freshwater algae. The new findings suggest that the sediments of the Yongning Formation were deposited during or after Eocene–Oligocene cooling and are Oligocene in age. This also supports the biostratigraphy based on rare mammal finds. The fossils of Lake Nanning are outstandingly well preserved and provide a great opportunity to study endemic lake radiations. Besides, the lake sediments are one of the most important Oligocene climate archives of the region.

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): Hui Sun, Xiaodong Liu Although some studies have shown that the uplift of the northern Tibetan Plateau (NTP) has an important influence on the climate of inland Asia, the respective roles played by different parts of the NTP in controlling regional aridification and dust cycling remains unclear. In this study, based on the geological facts that the NTP and its surrounding mountains have uplifted to a certain altitude since the Miocene, we used the dust-coupled regional climate model RegCM4.1 to explore the different impacts of the uplift of four mountain ranges (the Altai Mountains–Mongolian Plateau, the Tian Shan Mountains, the Pamir Mountains, and the Qilian Mountains) on the arid climate and dust cycle of inland Asia. The results showed distinct contributions of these different mountain ranges. With respect to aridity, the uplift of the Pamirs played a leading role in the aridification of inland Asia, causing the annual mean precipitation to decrease by 200% across a wide area of Northwest China owing to the “rain shadow” effect (a rain shadow is a dry area on the leeward side of a mountainous area). In terms of dust cycling, dust emissions and deposition increased in the Taklimakan Desert mainly due to the uplift of the Tian Shan Mountains and the Pamirs, the increase in magnitude of which was 10–20 times larger than that induced by the uplift of the Altai Mountains–Mongolian Plateau or Qilian Mountains. Besides, a narrow passage formed between the uplifted Altai Mountains–Mongolian Plateau and Tian Shan Mountains that accelerated the northwesterly air flow between them, thus increasing dust emissions in northern Xinjiang and the Gobi Desert. The increase in dust emissions in these two regions induced by the uplift of the Altai Mountains–Mongolian Plateau was 7–20 times greater than that induced by the uplift of the three other mountain ranges. Results also showed that the uplift of the Qilian Mountains not only controlled the dust emissions and deposition on the Loess Plateau, but also blocked the transportation of dust from Northwest China to the middle and lower reaches of the Yangtze River, leading to the dust loading being reduced by 10–20% in South China. The findings of this study improve our understanding of the influence of NTP tectonic uplift on change in the arid climate and dust cycle of inland Asia.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Ruiwen Zong, Yiming Gong One kind of mysterious underwater circle observed on the seafloor near southern Amami-Oshima Island in subtropical Japan has attracted widespread attention, but its origin has long been unknown. In recent years, based on successive underwater photography, they were shown to represent the patterned structures constructed by male pufferfishes. Here we present a large radial trace fossil from the Upper Devonian Hongguleleng Formation in western Junggar, Xinjiang, northwestern China. They are circular or near-circular patterned structures consisting of numerous radial grooves and ridges. Based on morphological analysis of these specimens and comparison with the modern patterned structures made by pufferfish for courtship, we suggest that this trace fossil may be patterned structure made by male fish in the Devonian to attract females. If true, these structures would be the first reported example of courtship behaviour in the trace fossils of fish, and suggest that animal courtship behaviour has existed for at least 360 million years. These trace fossils provide new material for research on the breeding strategies and sexual selection of Devonian animals, and new insight on the origin and evolution of courtship behaviour.

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): Pierre Moissette, Jean-Jacques Cornée, Assimina Antonarakou, George Kontakiotis, Hara Drinia, Efterpi Koskeridou, Theodora Tsourou, Konstantina Agiadi, Vasileios Karakitsios In the eastern Mediterranean, the island of Crete offers excellent exposures of upper Miocene marine deposits. Three detailed sections of the Tortonian/Messinian sedimentary succession were measured and sampled in three different basins (from west to east: Chania, Heraklion, and Sitia). The biostratigraphic analysis based on planktonic foraminifera yielded ages ranging from about 7.58 to 6.72 Ma. Nine bioevents were also recognised and provided good correlations between the studied sections. Rich benthic faunas (commonly occurring together with fish otoliths) have furthermore been recovered and analysed: foraminifera, mollusc (mostly bivalves), bryozoans, and ostracods. The autochthonous assemblages suggest deposition at middle-upper bathyal depths at the base and outer-inner shelf in the upper parts of the sections. The shallowing upward trend observed in all three sections is accompanied by the occurrence in a few Messinian levels of allochthonous fossils transported downslope and deposited in deep-water environments. Dysoxic episodes were moreover recorded in some beds, mostly in the Messinian. A comparison with other coeval basins and faunas indicates that similar palaeoenvironmental conditions predominated throughout the Mediterranean Sea during the late Miocene. This is consistent with the postulate of open connections (through marine corridors) between the Mediterranean and the Atlantic, presumably until late in the Messinian.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Deborah N. Tangunan, Karl-Heinz Baumann, Janna Just, Leah J. LeVay, Stephen Barker, Luna Brentegani, David De Vleeschouwer, Ian R. Hall, Sidney Hemming, Richard Norris A detailed paleoenvironment reconstruction from the Mozambique Channel, western Indian Ocean, based on the calcareous nannoplankton assemblages was conducted for the interval between 2.85 and 1.85 Myr. This study covers the period during which the successive extinction of the last five species of discoasters occurred. New productivity data obtained from the abundances of the Discoaster species ( Discoaster brouweri , D . triradiatus , D . pentaradiatus , D . surculus , and D . tamalis ) and other indicative calcareous nannoplankton taxa showed abundance variations, which were at paced with the 100, 41, and 23 kyr astronomical periodicities. A shift in the productivity and water-column stratification proxies occurred at ~2.4 Ma, after the onset of the Northern Hemisphere glaciation. Here we propose that the variability recorded at International Ocean Discovery Program Site U1476 reflects the interplay between forcing associated with warm tropical Pacific and cold southern ocean influences. The former is shown by consistent occurrence of warm water taxa ( Calcidiscus leptoporus , Oolithotus spp., Rhabdosphaera clavigera , Syracosphaera spp., Umbellosphaera spp.), typical of Indonesian Throughflow surface waters. On the other hand, the occurrence of Coccolithus pelagicus indicates the influence of cold, nutrient-rich sub-Antarctic surface waters. A more mixed water column initiated at ~2.4 Ma, and a consequent productivity increase led to the gradual reduction of the Discoaster species, until their extinction at 1.91 Ma. This period was characterized by the low values of the Florisphaera profunda index and high abundances of upper photic zone flora, indicative of nutrient-rich surface water conditions. High productivity at the location during this period could have also been amplified by localized upwelling events driven by the Mozambique Channel eddies.

Description: Publication date: 15 September 2018 Source: Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 505 Author(s): Gustavo Prado de Oliveira Martins, Vanessa Maria da Costa Rodrigues-Francisco, Maria Antonieta da Conceição Rodrigues, Hermínio Ismael de Araújo-Júnior The continental colonization process by plants is an underexplored theme in Brazil, especially concerning taphonomic studies of plants that existed during this age. This study aims to interpret the taphonomic and paleoenvironmental settings that best represent the fossil plant assemblages preserved in the upper strata of the Furnas Formation (Lower Devonian of Paraná Basin), at Jackson de Figueiredo county, municipality of Jaguariaíva (Paraná), clarifying the potential of these fossil plant assemblages for paleogeographic reconstructions. Taphonomic and sedimentological signatures were analyzed and submitted to multivariate statistical analyses (cluster and correspondence analyses). Two taphonomic groups were identified (Taphofacies A and B). The interpretation of the two groups allowed the visualization of: Taphofacies A, which consists of samples with a dispersed degree of packing, fragmented plant fossils, 40% mica with sizes between 0.5 and 1 mm and no trace fossils, is representative of relatively high-energy conditions; and Taphofacies B, which consists of densely packed plants with partial degree of fragmentation, 10% mica with sizes under 0.5 mm and both horizontal and vertical trace fossils, is representative of relatively low-energy conditions. Our taphonomic data are consistent with previous facies interpretations of a lagoon/interdistributary bay environment. In this context, taphofacies A represents episodic sedimentation events influenced by fluvial dynamics, yielding assemblages that are not suitable for paleogeographic interpretations, while Taphofacies B represents fossil assemblages originated in a low-energy sedimentary regime, with utility for paleogeographic reconstructions.