Calcareous nannofossils (1-30 μm) are biomineralized calcitic remains of marine planktonic algae and are abundant in the marine sedimentary archives. Among nannofossils, the Nannoconus group was the main planktonic carbonate bio-producer in Early Cretaceous seas (~152 - ~120 Ma) with their heavy carbonate exoskeleton (~200 - 1100 picogram), responsible for massive carbonate accumulations. These massively produced bio-calcites must have certainly significantly modified the marine chemistry upon transfer to the ocean sedimentary record.

Nannoconus are conical in shape with interlocking arrangement of calcitic plates (length ~ 0.5 – 1 µm, thickness ~ 100 nm) spanned by a central canal. Different morpho-groups with different stratigraphic ranges have been recognized. However, the 3D structure of Nannoconus is not yet fully understood and needs to be investigated to analyze the inter-plates geometrical relation and reconstruct the growth pattern. Moreover, some studies show that bio-molecules, such as amino-acids, assert control on the shape of constituent elements, such as plates¹, the overlapping pattern, and the inter-elemental geometrical² relation in bio-calcified structures formed by individual components, with case studies in calcareous plankton. Similarly, an important question can be asked: Did the micro-structural arrangement of plates of Nannoconus (the bio-calcified structure) also result from a “particular biomolecule” assisted calcification? So far, there are not enough studies explaining the exoskeletal construction from the calcitic plates to answer the mentioned question. To understand the microstructure at the nanometer level, finer than the thickness of individual plate we have applied a set of Ptychography X-ray computed tomography (PXCT) with synchrotron radiation³ at SWING Beamline of SOLEIL (French synchrotron), Paris, France, on several well-preserved Nannoconus.

The experiment resulted in a series of tomographic image slices (with ~ 40 nm 3D resolution) for the whole exoskeleton of each specimen of Nannoconus. The images are combined in ORS-Dragonfly software to observe the 3-dimensional internal and external view of individual specimens and to separate a plate from each specimen of Nannoconus.

The 3D observation and the segmentation of the plates have shown different features. These plates rotate in an anticlockwise overlapping pattern with a proper angular increment between two successive plates. Such rotations lead to form layers arranged in a helical manner to create the entire exoskeleton. Each species of Nannoconus is characterised by a particular shape of the calcitic plate. Hence, the physical parameters such as anticlockwise overlapping, plate-shape, and geometrically regulated “plate-to-layers” micro-structures are very similar to structural features as seen in some bio-molecule influenced calcification^1,2 This suggests that bio-molecule(s) have substantial influence in regulating the micro-structure in Nannoconus. The regulation on the micro-structure to maintain a particular geometric relation among the plates possibly controlled the numbers of plates, creating a massive exoskeleton of Nannoconus.

¹Orme, C. A., et al., Nature 411.6839 (2001): 775-779, ²Jiang, W. et al., Nat. Commun. 8, 15066 (2017), ³Dierolf, M. et al., Nature 467, 436-439 (2010).

How to cite: Chowdhury, R., Giraud, F., Fernandez-Martinez, A., Cesar da-Silva, J., Kulow, A., Boudjehem, R., Hazemann, J.-L., Dupraz, M., Perez, J., Suchéras-Marx, B., and Garbarino, G.: "Bio-molecule" based calcification in Nannoconus, an extinct group of planktonic algae approximately 150 million years old, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1111, https://doi.org/10.5194/egusphere-egu24-1111, 2024.

Middle Miocene sediments in the South-West Banat area were identified based on deep exploration drilling. Based on the identified macrofauna, microfauna and microflora from 15 wells of southwestern Banat, detailed biostratigraphy of the Middle Miocene sediments was made. The biostratigraphy of the studied Middle Miocene sediments of southwestern Banat is based on the standard biozones and biozonations used in several areas of Central Paratethys (Petrovic, 1970; Jiricek, 1975; Papp & Schmid, 1985; Cicha i dr., 1998; Harzhauser & Piller, 2004, Harzhauser & Piller, 2007; Hohenegger i dr., 2014).

Micropaleontological studies were performed using two methods: washed residues and thin sections method. During micropaleontological studies, the semiquantitative analysis determined relative abundance of planktonic and benthic foraminifera, as well as the presence of other fossil organisms (calcareous nanoplankton, ostracodes, molluscs).

On the basis of determined foraminifera associations, two biostratigraphic zones were established into the Badenian stage and two biostratigraphic zones into the Sarmatian stage. In the Badenian sediments there are associations of foraminifera that correspond to upper levels of the Lower Badenian (Globigerinoides trilobus/Orbulina suturalis zone) and upper levels of the Upper Badenian (Ammonia beccarii/ Elphidium crispum zone). In the Sarmatian sediments there are associations of foraminifera corresponding to the lower parts of the Lower Sarmatian (Elphidium reginum zone) and the higher parts of the Lower Sarmatian (Elphidium hauerinum zone).

The results of biostratigraphic research show that foraminifer zones of the Middle Miocene are not developed in the area of southern Banat (Lower lagenide zone, Spiroplectinella carinata zone, Bolivina-Bulimina zone and Porosononion granosum zone). If we consider that these biostratigraphic zones are developed in depressions south from the Sava and Danube river (Drmljanska, Markovacka, Gradistanska, etc.), it can be concluded that in the research area of southern Banat, several tectonic phases during the Middle Miocene can be registered, which will be subject to further research

How to cite: Gajić, V. and Dulić, I.: Biostratigraphy of the Middle Miocene sediments in boreholes from southern Banat, Serbia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21151, https://doi.org/10.5194/egusphere-egu24-21151, 2024.

During the early Tremadocian (Cordylodus lindstromi and Cordylodus angulatus zones), the Baltoscandian epicratonic basin displayed environmental heterogeneity. The basin included a black shale depocentre, bordered in North Estonia by coastal plains and shoal complexes featuring extensive brachiopod shell accumulations. At this juncture, obolid-dominant brachiopod communities near the shore had become extinct. Allochthonous shell beds, manifested as biogenic phosphorites, were remnants eroded from Furongian shoal bioaccumulations.

Unconsolidated quartzose sand packages, displaying bidirectional cross laminae and intermittently punctuated by thin black shale intercalations and contemporaneous glendonite clusters (a pseudomorph of ikaite), were deposited in tidally influenced foreshore-to-shoreface settings. The nearshore reworking and condensation of sand phosphorites served as indicators of coastal eutrophication. This eutrophication likely led to a significant seasonal enrichment of the water column with nutrients, linked to fluctuations in dissolved oxygen. An overlooked potential contributor to this eutrophication and water pollution, coinciding with the widespread deposition of kerogenous clay and the extinction of shallow marine biota, was the rise in phosphate nutrients and an increased biomass of phytoplankton.

Toxic effects were likely triggered by the extensive Furongian obolid shelly substrates, submerged during the marine transgression. The presence of substantial amounts of dissolved phosphate in the water during this period was evidenced by the deposition of concretions and crusts of chemogenic phosphorites outlining the periphery of the black shale depocentre.

How to cite: Holmer, L., Popov, L., Ghobadipour, M., and Alvaro Blasco, J.: Biogenic Phosphate Pollution Inducing Eutrophication as a Catalyst for the Decline of Obolid-Dominated Brachiopod Communities in the Early Tremadocian of East Baltica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1518, https://doi.org/10.5194/egusphere-egu24-1518, 2024.

Small shelly fossils have long been recognized as important evidence of both metazoan evolution and biomineralization during the Cambrian radiation. The marked decline in the occurrence, diversity and abundance of small shelly fossils in the middle to late Cambrian, when compared with the early Cambrian, has often been regarded as representative of a closing phosphatization window. Small shelly fossil-like assemblages have, however, been sparsely reported from the entirety of the Phanerozoic, indicating preservation of small shelly fossils is possible outside of the Cambrian. To identify possible factors enhancing small shelly fossil preservation, five microfacies (normal bioclastic limestone, flat-pebble conglomerates with bioclasts, hummocky cross-stratified grainstones with bioclasts, bioclastic grainstone in hardgrounds and glauconite bioclastic wackestone-packstone) from the Houjiashan, Mantou, Maozhuang, Xuzhuang and Zhangxia formations, Cambrian Series 2 to Miaolingian in North China are compared to assess for differences in preservation potential. The majority of extracted small shelly fossils from the studied section come from normal bioclastic limestones, but diversity is generally low and ornament is poorly preserved (except for original organophosphatic shells). The diversity of shelly fossils in flat-pebble conglomerates with bioclasts and hummocky cross-stratified grainstone with bioclasts are similar to normal bioclastic limestone, but with a greater abundance of articulated brachiopods. Bioclastic grainstone from hardgrounds facilitate some soft tissue preservation but the overgrowth of apatite grains on some specimens means shell structures are poorly preserved. Small shelly fossils extracted from glauconite bioclastic wackestone-grainstones are the best preserved, in regard to shell microstructure, and diversity is highest in these layers. These results suggest that limestones with authigenic glauconites could possibly be a good indicator for well-preserved small shelly fossils and that preservation potential of small shelly fossils is likely linked to differences between microfacies in early to middle Cambrian, North China.

How to cite: Hu, Y., Topper, T., Strotz, L., Liang, Y., Liu, F., Fu, R., Song, B., Wang, Z., and Zhang, Z.: Microfacies controlling the preservation of small shelly fossils from the lower to middle Cambrian of North China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10282, https://doi.org/10.5194/egusphere-egu24-10282, 2024.

The Mesozoic Shaqra group has been the subject of numerous previous studies because of its 13 petroleum-producing reservoirs dispersed across different formations. Several geologists thoroughly examined the Dhruma Formation, the second formation of the Shaqra group, from a petrographic and sedimentological standpoint. However, other than the report by Kaminski et al. (2018), there are only a few micropaleontological investigations of the marly units within this formation, and no thorough evaluation of the maximum flood surfaces utilizing microfossil contents, such as planktonic foraminifera, has been carried out. The diversity, quantity, and preservation mode of planktonic foraminifera in older rocks could give insight into changes in past sea level or in other words the maximum flood surfaces (MFS). These free-floating foraminifera replace shallow-water species during transgressions as sea levels rise; their numbers peak at the maximum flood surface when sufficient water depths and nutrient-rich waters provide them with an ideal depositional environment. To provide new evidence for high-resolution sequence stratigraphy, we are attempting to trace the maximum flood surfaces within the carbonates and marl units of the Dhruma formation by examining their microfossil content. The material under consideration was collected from a marly D4 unit exposure (~15 m thick) located on Highway Road no. 5395, southwest Riyadh City, about 1 km from a Saudi poultry farm (N24°12'48'', E46° 14'5''E). The samples were obtained from the lower marly limestone part of the D4 Unit and examined using traditional micropaleontological procedures and the acetolysis technique. The main new finding of this study is that, as previously noted in Unit D5, the bottom part of Unit D4 contains the low-spired species Globuligerina sp. and the high-spired variant Conoglobigerina sp. Alongside the planktonic foraminifera, there is a benthic foraminiferal assemblage consisting of a mixture of smaller agglutinated species (Haplophragmoides and Nautiloculina) and calcareous species (polymorphinids and nodosariids). This assemblage suggests conditions on an open sea shelf and characteristics of a Middle Jurassic foraminiferal content from a marly carbonate unit. Considering their small size, calcareous benthic foraminifera indicate the presence of an oligotrophic depositional environment for Unit D4. The D4 Unit of the Dhruma Formation contains planktonic foraminifera, which provides a novel correlation tool for determining a new maximum flooding surface between the J20 and J30 maximum flooding surfaces in the Middle East.

How to cite: Korin, A., Prayudi, S., and Kaminski, M.: A new record of the earliest planktonic foraminifera Conoglobigerina sp. and Globuligerina sp. from the Middle Jurassic (Bajocian) D4 unit of the Dhruma Formation in Saudi Arabia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6657, https://doi.org/10.5194/egusphere-egu24-6657, 2024.

Chuandianella ovata, a waptiid “bivalved” arthropod occurred in strara of Cambrian Series 2 and Stage 3 (ca. 521–514.5 Ma) along the western margin of the Yangtze plate, has been reported in numerous publications, whereas many morphological features still require further investigation. Herein, based on 1459 finely preserved specimens from eight localities of the Chengjiang biota, seventeen new characteristics are described and documented, and five previously described traits are revised. In our reconstruction, the cephalon bore a pair of stalked eyes with setae along the convex margin and annuli at the basal part of the eye lobes, a median triangular sclerite, one pair of biramous antennules, and three pairs of uniramous appendages that may represent the mandibules, maxillules and maxillae, respectively. According to microtomography and fossil imaging, the thorax houses nine pairs of appendages, each identified as a quadripartite, comprising a protopodite, a reduced endopodite, flap-like setose exopodite, and annulated epipodite with numerous lamellae. This appendicular morphology provides additional evidence for the presence of exites (epipodites) in Palaeozoic arthropods. Re-examination of the trunk limbs of Cambrian euarthropods indicates that exites may be a common feature that evolved deep in arthropod phylogeny.

How to cite: Liu, C., Fu, D., and Zhang, X.: Cambrian waptiid euarthropod Chuandianella from the Chengjiang biota, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9383, https://doi.org/10.5194/egusphere-egu24-9383, 2024.

The present study aims to investigate the change in the bivalve community in the Late Cretaceous of the Ariyalur Sub-basin, south India, along with the changing sea level, depositional sequence, and lithology. A drop in bivalve diversity was recognized from the siliciclastic facies of the Coniacian-Santonian to the carbonate facies of the Maastrichtian. Two-way cluster analysis identified five distinct bio-assemblages and a prominent shift in the dominant ecological guild. The Coniacian–Santonian assemblages are dominated by infaunal taxa that changed into epifaunal-dominated Maastrichtian assemblages. Although the effect of secondary diagenetic alteration might have played a role, non-metric multidimensional studies suggest that other factors, especially the change in substrate condition and corresponding adaptive strategies employed by different functional groups of bivalves, may potentially explain the shift in community structure across the studied interval.

How to cite: Mukhopadhyay, A., Paul, S., Poddar, A., Chattopadhyay, D., and Saha, R.: Long-term palaeoecological trends of the Late Cretaceous bivalves from Ariyalur, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-248, https://doi.org/10.5194/egusphere-egu24-248, 2024.

There were multiple attempts to investigate mollusks from loess sediment in Serbia, as this natural archive covers a great part of the northern territory of Serbia. However, these approaches did not have a large temporal coverage, as usually only the loess from the last glacial cycle was studied, rarely reaching the Middle Pleistocene. In recent years this research was extended until the MIS 24, according to the Danube loess stratigraphy (Marković et al., 2015). Here we present the latest information about snail species that lived in glacial conditions over the northern province of Serbia, Vojvodina. We enriched the list of found mollusks from earlier studies, by exploring the two oldest loess-palaeosol sections in Serbia, which when compiled into a composite profile cover almost one million years (Veliki Surduk – Stari Slankamen). Some problems exist when compiling all the findings of snail species in other loess sections in Serbia, such as the lack of stratigraphic interpretation in the early studies. This is why found shells from such locations can not be included in this list. We found that Chondrula tridens, Granaria frumentum, Helicopsis striata, Pupilla muscorum, Pupilla triplicata, Vallonia costata, Clausilia dubia, as well as Milacidae, Limacidae and Agriolimacidae were present from the earliest periods of loess accumulation in Serbia. The prevalent malacological assemblage of loess observed in Serbia during glacial periods suggests a predominance of mild climatic conditions characterized by a steppe environment. Conversely, less prevalent species indicate more rigorous environmental conditions, persisting during the coldest phases of certain glacials. Originally, the list of mollusks from Veliki Surduk – Stari Slankamen section included 41 species, but after adding the mollusks found in other profiles in Serbia, the list now has 62 species. The lowest diversity of mollusks was found in MIS 8. On the other hand, there were 55 species in the period MIS 2-4, but they are very diverse in their environmental preferences. Refinements and updates to this dataset require subsequent malacological investigations, which may yield the discovery of hitherto unrecorded species or the incorporation of newly identified taxa of the nine loess units formed during glacial conditions in Serbia.

How to cite: Radaković, M. G. and Marković, S. B.: How many species of loess mollusks were there in Serbia from MIS 24 to MIS 2?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11670, https://doi.org/10.5194/egusphere-egu24-11670, 2024.

Quaternary coral reef science has limited understanding of coral reef response to the Mid Pleistocene Climate Transition (MPT) (ca. 0.8–0.6 Ma) that triggered the Earth's transition into a dry, arid climate and eventually into a period of glacial-interglacial cycles. During this period many of the extant large reef systems initiated, for example barrier reefs around Pacific atolls and the Great Barrier Reef, however, data availability is low. North and South Scott reefs are isolated carbonate platforms on the North West Shelf of Australia that have outpaced subsidence and oceanographic stressors intermittently since the Miocene. The long-term carbonate platform evolution from ca. 20 Ma to present has been characterised using seismic stratigraphy and seismic geomorphology, integrated with industry well log data, but, high-resolution reconstructions of sedimentological and environmental processes controlling coral reef growth cycles have not been determined prior to the Holocene. Lithologic and chrono-stratigraphic interpretations of four fossil coral reef boreholes extending to 200 m below sea floor provide new insights into the sensitivities of coral reef response to regional (i.e., tectonics, oceanographic) and global (i.e., climate, eustacy) environmental forcing conditions at millennial scale resolution since the MPT. Depositional facies and paleoenvironmental reconstructions are based on; detailed logging and petrologic, mineralogic and sedimentary lithofacies analyses of four cores located on the windward and leeward reef crests of north and south Scott Reef. Coralgal assemblages and other reef biota (e.g., foraminifera) constrain paleowater depths and precise paleoenvironmental settings. New radiometric dating based on sample selection from hyperspectral and neutron scattering data are presented. We recognise distinct reef growth sequences within lithologic and chrono-stratigraphic units that correspond to global high sea levels within Marine Isotope Stages (MIS) 1 (Holocene), 5, 7, 8, 11, 13. Each reef growth sequences established on the drowned platforms during deglacial and interglacial sea levels. Hiatuses in reef growth represented by paleosol horizons in the core that signals subaerial exposure events during glacial (low sea level) periods. Significant variations in elevation, subsidence histories, paleo-coralgal communities and geomorphological features occur between the north and south reef, as well as spatially across each reef. Sequences of coral reef growth kept pace with deglacial sea level rise owing to favourable environmental and oceanographic conditions that allowed the cyclic re-establishment of shallow, moderate and deep-water coral reef development across both platforms since the MPT. A comprehensive review of comparable MPT-triggered coral reef sequences for Ribbon Reef 5 on the NE margin of Australia exposes some significant variations in reef response to eustatic (subsidence and sea level) and environmental controls, including: proximity to land, position along the continental shelf, terrigenous sediment influx, seabed geomorphology, ocean currents and nearby sites for coral larvae recruitment. Analysis of two newly acquired and two undescribed fossil coral reef cores provides a unique insight into the Quaternary history of a key site along the NWS, demonstrating how fossils can be used to reconstruct Earth history to answer broader questions in the bio and geological sciences with respect to coral reef ecological responses to climate change.

How to cite: Williams, C., Webster, J., Humblet, M., Braga, J., Renema, W., Nothdurft, L., Webb, G., Paumard, V., Lebrac, U., and Salles, T.: Coral reef response since the Mid-Pleistocene Climate Transition on the North West Shelf, Australia: Insights from fossil coral reef cores, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13516, https://doi.org/10.5194/egusphere-egu24-13516, 2024.

Norian time interval is a crucial period in Earth’s evolutionary history, characterized by several organic carbon-isotope perturbations in the carbon cycle that are closely related to global environmental change and biotic turnover (Zaffani et al., 2017). Among them, the Norian “chaotic carbon episode” has been recently reported globally in North America, Italy, and Japan, from shallow to pelagic environments (Whiteside and Ward, 2011; Zaffani et al., 2017; Jin et al., 2022; Sato et al., 2023). However, the mechanisms and timing of these events are poorly understood, especially in the eastern Tethys. In this study, we have investigated the carbon isotope profiles and conodont assemblage changes from the middle to upper Norian bedded carbonate rock succession in the Sanhedong section, Southwest China, to provide new insights into the Norian carbon cycle perturbation and its impact on marine biodiversity. We thus collected several samples for conodont biostratigraphic investigations and organic and carbonate carbon isotope (δ¹³C_org, δ¹³C_carb) and oxygen isotope data (δ¹⁸O_carb) along the study section. We identified various conodont genera, including some typical Norian Arcyrogondolella, Norigondollela, Mockina, and Primatella, and established detailed conodont biostratigraphy that indicates a middle to upper Norian age for the Sanhedong section. Furthermore, we detected a significant negative carbon isotope excursion (NCIE) across the middle/upper Norian, which can be globally correlated with the NCIE events reported from North America, the central Panthalassa Ocean, and the Tethys Ocean. We have also observed changes in conodont diversity and abundance associated with the NCIE.

Our study provides an accurate age and a high-resolution carbon isotope record for the Sanhedong section, revealing the global nature of the Norian carbon cycle perturbation and its impact on the biosphere in the eastern Tethys. Our preliminary results suggest that also the carbon isotope perturbation in Eastern Tethys may be associated to the middle-late Norian carbon-cycle perturbations, which were triggered by the emplacement of the Angayucham Large Igneous Province (Alaska). Further studies are needed to constrain the timing and magnitude of Norian volcanic activity.

Keywords: Norian, conodont biostratigraphy, carbon isotope perturbation, Eastern Tethys

Reference:

Jin, X., Du, Y., Bertinelli, A., Shi, Z., Preto, N., Zou, H., Ogg, J.G., Han, L., Wu, Q. and Rigo, M., 2022. Carbon-isotope excursions in the Norian stage (Upper Triassic) of the Baoshan terrane, western Yunnan, China. Journal of Asian Earth Sciences, 230, p.105215.

Sato, H., Nozaki, T., Onoue, T., Ishikawa, A., Soda, K., Yasukawa, K., Kimura, J.I., Chang, Q., Kato, Y. and Rigo, M., 2023. Rhenium-osmium isotope evidence for the onset of volcanism in the central Panthalassa Ocean during the Norian “chaotic carbon episode”. Global and Planetary Change, 229, p.104239.

Whiteside, J.H. and Ward, P.D., 2011. Ammonoid diversity and disparity track episodes of chaotic carbon cycling during the early Mesozoic. Geology, 39(2), pp.99-102.

Zaffani, M., Agnini, C., Concheri, G., Godfrey, L., Katz, M., Maron, M. and Rigo, M., 2017. The Norian “chaotic carbon interval”: new clues from the δ13Corg record of the Lagonegro Basin (southern Italy). Geosphere, 13(4), pp.1133-1148.

How to cite: Wu, Q., Jin, X., Du, Y., Shi, Z., Zhang, X., Bertinelli, A., and Rigo, M.: Norian conodont biostratigraphy and carbon isotopic perturbations in the Lanping-Simao terrane, Eastern Tethy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-429, https://doi.org/10.5194/egusphere-egu24-429, 2024.

The late Miocene fossil land mammalian sites Udabno (Georgia) and Eldari (Azerbaijan) are found in the Middle Kura Basin, in the fluvial sediments along the Kura bay deposited during regression of the Eastern Paratethys and represent the earliest terrestrial faunal evidence from the area. The Udabno and Eldari fossil vertebrate sites are roughly contemporaneous and supposedly embrace time span from ca. 9.5 to 7.5 Ma. Yet, there remain correlation issues and questions regarding the detailed chronological framework of the deposits. These questions are under study.

The Udabno and Eldari bovid remains were revised, research involved the Georgian National Museum collections only. This study aims to clarify taxonomy and to draw biostratigraphic and paleogeographic conclusions. Following taxa were identified:

Tragoportacini: Miotragoceros valenciennesi eldaricus (Eldari), Miotragoceros valenciennesi maius (Udabno),Tragoportax sp. (Udabno);

Antilopini:      Gazella cf. capricornis (Eldari), G. cf. pilgrim (Udabno), Prostrepsiceros rotundicornis (Udabno), Prostrepsiceros vallesiensis (Eldari), Aff. Hispanodorcas orientalis (Udabno);

Caprini:         Tethytragus sp. (Udabno), Skoufotragus sp.(Udabno), Caprini gen et sp nov. (Udabno);

Alcelaphini:    Udabnocerus georgicus (Udabno-Hadjia, Azerbaijan);

Bovidae indet.: Bovidae indet. 1 (Udabno) – dwarf antelope, strongly posteriorly inclined horn cores without basal swelling, with posterior keel, without torsion. Eotraginae?; Bovidae indet. 2 (Udabno, Eldari) - dwarf antelope, long upright horn cores without torsion, without keels - Hypsodontinae?; Bovidae indet. 3 (Udabno) - dwarf antelope, horn cores transversally compressed, with anterior keel and very weak homonymous torsion- Hypsodontinae?

Lack of exact stratigraphic information for most of these fossils does not allow to judge about their stratigraphic distribution. Yet, a strong Vallesian component in this bovid composition is evident (Miotragoceros, Prostrepsiceros vallesiensis) suggesting MN10. Presence of Middle Miocene relict bovids (Tethytragus sp., possible Hypsodontinae and Eotraginae) is indeed striking and enhances the evidence of the Vallesian age. Tragoportax, Gazella capricornis, G. pilgrimi, Prostrepsiceros rotundicornis, Skoufotragus are among the typical Turolian taxa. Yet, absence of Oioceros- a very frequent antelope, that appears in the Early Turoloan might be a significant biostratigraphic indicator, pointing to the earliest Turolian (earliest MN11) as a minimum age.

The core of the bovid fauna is composed of “local”, Greko-Iranian taxa. Yet, out of Africa dispersal can be the immediate explanation for the presence of a primitive, early alcelaphin bovid -Udabnocerus georgicus. However, the story might be more complicated. This fossil comes from the locality Hadjia (Azerbaijan) of the Udabno site. We did not have a possibility to survey this place. Yet geoglogical maps indicate that youngest deposits in the area is Eldari Formation with supposed minimum age ca. 7.5 Ma. what makes Udabnocerus as old or even older than the African alcelaphine record. It is paradoxical evidence, once again reminding us how limited is our vision of the past world.

The study was conducted in the framework of Shota Rustaveli National Science Foundation of Georgia grant #FR-21-1979.

How to cite: Bukhsianidze, M.: Revisiting the earliest terrestrial fossil record from the paleo Kura bay (Eldari and Udabno faunas, Late Miocene, South Caucasus) – diversity of bovids, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7327, https://doi.org/10.5194/egusphere-egu24-7327, 2024.

Abstract: The adaptation and survival of prehistoric humans in the alpine and hypoxic environment of the Tibetan Plateau is the focus of multidisciplinary research. As an important prehistoric human hand-footprints site for the study of prehistoric human activities on the Tibetan Plateau, Quesang site has witnessed prehistoric human arrivals in the area at least twice, which occurred in the Middle Pleistocene, about 200ka and the early Holocene, about 7.2ka. The early and middle Holocene hand-footprints are distributed on the spring deposits near the modern active hot springs, which are distributed downstream along both sides of the gully. During a recent field investigation, we found a series of prehistoric human footprints and trampling marks on the travertine in the middle and lower reaches of the active spring. Through the stratigraphic and geomorphological analysis of travertine deposit, 3D modeling and morphological study of hand-footprints, as well as U-Th and OSL dating of hand and foot prints and strata, we have obtained the following results: Modern active hot springs were formed after 18ka, and a large amount of travertine was deposited near the spring mouth, on both sides and downstream of the gully. The newly discovered footprints and trampling marks are distributed on the middle and lower travertine sedimentary fans of the gully, which are formed in ~ 8.8ka and ~ 14ka, respectively. In the extremely cold and anoxic environment of the Tibetan Plateau, Quesang hot spring is undoubtedly a very attractive survival resource, attracting ancient humans to patronize here frequently for a long time. The discovery of hand-footprints also provides new evidence for the expansion and occupation of prehistoric humans on the Tibetan Plateau.
Keywords：Post Last Glacial Maximum, hand-footprints, travertine, Quesang spring, prehistoric human activities

How to cite: Gao, Y.: Prehistoric human hand-footprints on the central tibetan plateau after the post last glacial maximum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8231, https://doi.org/10.5194/egusphere-egu24-8231, 2024.