Late Mesoproterozoic – early Neoproterozoic organic‐walled microfossils from the Madhubani Group of the Ganga Valley,northern India

The age of the sedimentary basement of the Ganga Valley in northern India, which is represented by the entirely subsurface Ganga Supergroup, is key for addressing issues related to the tectonic history of the Himalaya. However, the stratigraphic correlations between the Ganga Supergroup in the Ganga Valley, the Vindhyan Supergroup in cratonic India to the south, and Proterozoic successions in the Lesser Himalaya to the north have long been a matter of controversy. This is largely because of the poor age constraint of the Madhubani Group of the upper Ganga Supergroup, which has been variously interpreted as Proterozoic, lower Palaeozoic, or even Mesozoic. To address this issue, we used a low manipulation maceration technique to extract organic‐walled microfossils from the Ujhani and Tilhar formations of the lower Madhubani Group. Our study recovered a total of 24 taxa, including Devisphaera corallis gen. et sp. nov. The co‐occurrence of Trachyhystrichosphaera aimika, Caudosphaera expansa and Annulusia annulata in the lower Madhubani Group indicates a late Mesoproterozoic to early Neoproterozoic age. Thus, the biostratigraphical data suggest a >300 myr depositional gap between the Madhubani Group and the immediately underlying Bahraich Group, which has been independently constrained to be upper Palaeoproterozoic to lower Mesoproterozoic in age. Therefore, the first‐order stratigraphic architecture, with a Palaeoproterozoic–Mesoproterozoic succession unconformably overlain by a Mesoproterozoic–Neoproterozoic succession, is closely similar throughout the Vindhyan Basin, Ganga Valley and Lesser Himalaya, suggesting a shared sedimentary and tectonic history among them.     

Absence of biomarker evidence for early eukaryotic life from the Mesoproterozoic Roper Group: Searching across a marine redox gradient in mid‐Proterozoic habitability

By about 2.0 billion years ago (Ga), there is evidence for a period best known for its extended, apparent geochemical stability expressed famously in the carbonate–carbon isotope data. Despite the first appearance and early innovation among eukaryotic organisms, this period is also known for a rarity of eukaryotic fossils and an absence of organic biomarker fingerprints for those organisms, suggesting low diversity and relatively small populations compared to the Neoproterozoic era. Nevertheless, the search for diagnostic biomarkers has not been performed with guidance from paleoenvironmental redox constrains from inorganic geochemistry that should reveal the facies that were most likely hospitable to these organisms. Siltstones and shales obtained from drill core of the ca. 1.3–1.4 Ga Roper Group from the McArthur Basin of northern Australia provide one of our best windows into the mid‐Proterozoic redox landscape. The group is well dated and minimally metamorphosed (of oil window maturity), and previous geochemical data suggest a relatively strong connection to the open ocean compared to other mid‐Proterozoic records. Here, we present one of the first integrated investigations of Mesoproterozoic biomarker records performed in parallel with established inorganic redox proxy indicators. Results reveal a temporally variable paleoredox structure through the Velkerri Formation as gauged from iron mineral speciation and trace‐metal geochemistry, vacillating between oxic and anoxic. Our combined lipid biomarker and inorganic geochemical records indicate at least episodic euxinic conditions sustained predominantly below the photic zone during the deposition of organic‐rich shales found in the middle Velkerri Formation. The most striking result is an absence of eukaryotic steranes (4‐desmethylsteranes) and only traces of gammacerane in some samples—despite our search across oxic, as well as anoxic, facies that should favor eukaryotic habitability and in low maturity rocks that allow the preservation of biomarker alkanes. The dearth of Mesoproterozoic eukaryotic sterane biomarkers, even within the more oxic facies, is somewhat surprising but suggests that controls such as the long‐term nutrient balance and other environmental factors may have throttled the abundances and diversity of early eukaryotic life relative to bacteria within marine microbial communities. Given that molecular clocks predict that sterol synthesis evolved early in eukaryotic history, and (bacterial) fossil steroids have been found previously in 1.64 Ga rocks, then a very low environmental abundance of eukaryotes relative to bacteria is our preferred explanation for the lack of regular steranes and only traces of gammacerane in a few samples. It is also possible that early eukaryotes adapted to Mesoproterozoic marine environments did not make abundant steroid lipids or tetrahymanol in their cell membranes.     

A SERIES OF MONOGRAPHS AND MEMOIRS (ISSN 0300-9491) TO SUPPLEMENT LETHAIA

Acid-resistant organic microfossils are described from outcrops and a boring through the middle and upper units of the VisingsÖ Beds in southern Sweden. 21 previously described acritarch species have been identified, and five new species are erected. The acritarchs include simple, although characteristically ornamented sphaeromorphs, one polygonomorph species and one acanthomorph species. Their mode of occurrence and possible lithofacial relationships are discussed. The acritarchs from the middle unit of the Visingso Beds indicate a Late Riphean age. The upper unit contains acritarchs previously known from Vendian and Lower Cambrian strata in the U.S.S.R., China and elsewhere. A Vendian age is suggested for this unit. A glacial origin is suggested for boulder beds in the middle unit of the VisingsÖ Beds.     

Silicified Polybessurus from the Ediacaran Doushantuo Formation records microbial activities within marine sediments

Polybessurus, as a common element of the late Mesoproterozoic to early Neoproterozoic microfossil assemblages, has yet no confirmed record from post-Cryogenian strata. In this study, we report Polybessurus sp. from the Ediacaran Doushantuo Formation chert nodules in western Hubei Province, South China. Polybessurus specimens from the Doushantuo Formation are identical to their pre-Cryogenian counterparts in morphology (stacked concave lamellae), composition (organic matter), and preservational mode (silicification). The Doushantuo specimens generally have large tubes (average diameter ~157 μm, maximum diameter ~450 μm), and are often preserved separately and parallel to the bedding plane, whereas the pre-Cryogenian specimens have relatively small tubes (mostly thinner than 100 μm in diameter), and are often preserved gregariously and perpendicular to the bedding plane. Polybessurus may be formed by a variety of benthic micro-organisms, mainly cyanobacteria, e.g., stalk forming taxa like Cyanostylon and endolithic taxa like Solentia, that are capable of secreting EPS (extracellular polymeric substance) unidirectionally to push itself forward in the sediment. The producers of Polybessurus may have played a role in the benthic microbial community by making microburrows, affecting textures and microenvironments of inshore sediments. As the first unambiguous record of Polybessurus from Ediacaran strata, our new findings extend its distribution from the late Mesoproterozoic–early Neoproterozoic to the late Neoproterozoic.     

Using modern low-oxygen marine ecosystems to understand the nitrogen cycle of the Paleo- and Mesoproterozoic oceans

During the productive Paleoproterozoic (2.4–1.8 Ga) and less productive Mesoproterozoic (1.8–1.0 Ga), the ocean was suboxic to anoxic and multicellular organisms had not yet evolved. Here, we link geologic information about the Proterozoic ocean to microbial processes in modern low-oxygen systems. High iron concentrations and rates of Fe cycling in the Proterozoic are the largest differences from modern oxygen-deficient zones. In anoxic waters, which composed most of the Paleoproterozoic and ~40% of the Mesoproterozoic ocean, nitrogen cycling dominated. Rates of N₂ production by denitrification and anammox were likely linked to sinking organic matter fluxes and in situ primary productivity under anoxic conditions. Additionally autotrophic denitrifiers could have used reduced iron or methane. 50% of the Mesoproterozoic ocean may have been suboxic, promoting nitrification and metal oxidation in the suboxic water and N₂O and N₂ production by partial and complete denitrification in anoxic zones in organic aggregates. Sulfidic conditions may have composed ~10% of the Mesoproterozoic ocean focused along continental margins. Due to low nitrate concentrations in offshore regions, anammox bacteria likely dominated N₂ production immediately above sulfidic zones, but in coastal regions, higher nitrate concentrations probably promoted complete S-oxidizing autotrophic denitrification at the sulfide interface.     

Fedomia mikhaili—A new spicule-bearing organism of sponge grade from the Vendian (Ediacaran) of the White Sea, Russia

The Vendian fossil locality on the Solza River is one of the most productive in the White Sea Region. The fossiliferous deposits belong to the Upper Vendian Verkhovka Formation correlated lithologically with strata dated at 558 ± 1 to 555.3 ± 0.3 Ma in adjacent regions. This locality is characterized by yielding more than 10 well-represented Ediacaran genera. Elongated imprints of Fedomia mikhaili, n. gen. et n. sp., are common at the Solza River fossil locality. The new taxon is characterized by its six- to eight-rayed star-shaped concave structures with diameters of 2–5 mm. The organism can be reconstructed with sacciform thin-walled body attached basally to the substrate. The star-shaped structures may be spicules that appear to be rather flexible than rigid. The new genus, Fedomia, shows some similarities to Eiffelia Walcott, 1920 from the Middle Cambrian of British Columbia, and thus is interpreted as an organism of sponge grade. The new taxon could represent an additional phylogenetic link between the Ediacaran and Cambrian worlds.     

Origin and early evolution of photosynthetic eukaryotes in freshwater environments: reinterpreting proterozoic paleobiology and biogeochemical processes in light of trait evolution

Phylogenetic analyses were performed on concatenated data sets of 31 genes and 11,789 unambiguously alignable characters from 37 cyanobacterial and 35 chloroplast genomes. The plastid lineage emerged somewhat early in the cyanobacterial tree, at a time when Cyanobacteria were likely unicellular and restricted to freshwater ecosystems. Using relaxed molecular clocks and 22 age constraints spanning cyanobacterial and eukaryote nodes, the common ancestor to the photosynthetic eukaryotes was predicted to have also inhabited freshwater environments around the time that oxygen appeared in the atmosphere (2.0–2.3 Ga). Early diversifications within each of the three major plastid clades were also inferred to have occurred in freshwater environments, through the late Paleoproterozoic and into the middle Mesoproterozoic. The colonization of marine environments by photosynthetic eukaryotes may not have occurred until after the middle Mesoproterozoic (1.2–1.5 Ga). The evolutionary hypotheses proposed here predict that early photosynthetic eukaryotes may have never experienced the widespread anoxia or euxinia suggested to have characterized marine environments in the Paleoproterozoic to early Mesoproterozoic. It also proposes that earliest acritarchs (1.5–1.7 Ga) may have been produced by freshwater taxa. This study highlights how the early evolution of habitat preference in photosynthetic eukaryotes, along with Cyanobacteria, could have contributed to changing biogeochemical conditions on the early Earth.     

Redox heterogeneity of subsurface waters in the Mesoproterozoic ocean

A substantial body of evidence suggests that subsurface water masses in mid‐Proterozoic marine basins were commonly anoxic, either euxinic (sulfidic) or ferruginous (free ferrous iron). To further document redox variations during this interval, a multiproxy geochemical and paleobiological investigation was conducted on the approximately 1000‐m‐thick Mesoproterozoic (Lower Riphean) Arlan Member of the Kaltasy Formation, central Russia. Iron speciation geochemistry, supported by organic geochemistry, redox‐sensitive trace element abundances, and pyrite sulfur isotope values, indicates that basinal calcareous shales of the Arlan Member were deposited beneath an oxygenated water column, and consistent with this interpretation, eukaryotic microfossils are abundant in basinal facies. The Rhenium–Osmium (Re–Os) systematics of the Arlan shales yield depositional ages of 1414 ± 40 and 1427 ± 43 Ma for two horizons near the base of the succession, consistent with previously proposed correlations. The presence of free oxygen in a basinal environment adds an important end member to Proterozoic redox heterogeneity, requiring an explanation in light of previous data from time‐equivalent basins. Very low total organic carbon contents in the Arlan Member are perhaps the key—oxic deep waters are more likely (under any level of atmospheric O₂) in oligotrophic systems with low export production. Documentation of a full range of redox heterogeneity in subsurface waters and the existence of local redox controls indicate that no single stratigraphic section or basin can adequately capture both the mean redox profile of Proterozoic oceans and its variance at any given point in time.     

Secular distribution of Burgess-Shale-type preservation

Burgess-Shale-type preservation is defined as a taphonomic pathway involving the exceptional organic preservation of non-mineralizing organisms in fully marine siliciclastic sediments. In the Phanerozoic it occurs widely in Lower and Middle Cambrian sequences but subsequently disappears as a significant taphonomic mode. The hypothesis that this distribution derives solely from a secular increase in the depth of bioturbation is falsified: low bioturbation indices do not prevent the rapid enzymatic degradation of organic structure, nor do they account for the conspicuous absence of comparable preservation during the Vendian. An earlier, Late Riphean (ca. 750–850 Ma), interval of enhanced organic-walled fossil preservation suggests a long-term recurrence in Burgess-Shale-type taphonomy that is independent of metazoan activity. A model based on the potentially powerful anti-enzymatic and/or stabilizing effects of clay minerals on organic molecules is proposed to account for Burgess-Shale-type preservation. Long-term changes in average clay mineralogies and the ocean chemistry that determines their interaction with organic molecules are likely to have induced the pronounced secular distribution of these fossil biotas, while regional variations in tectonism, weathering, etc., explain their non-uniform geographic distribution; the close correlation between exceptional, organic-walled fossil preservation and volcano-genic sedimentation in Tertiary lake deposits provides a compelling analogue. Recognition of a temporal control on Burgess-Shale-type preservation constrains the evolutionary scenarios that can be drawn from such biotas; significantly, neither the initial rate of appearance, nor the ultimate fate of Burgess-Shale-type taxa can be directly assessed. □ Taphonomy, exceptional preservation, organic preservation, fossil Lagerstätten, Burgess Shale, clay mineralogy, clay-organic interactions, secular change, Cambrian, Proterozoic.     

Jurassic biostratigraphy and paleoenvironmental evolution of the Malaguide complex from Sierra Espuña (Internal Betic Zone, SE Spain)

Jurassic studies in the Internal Zones of the Betic Cordillera are scarce since this zone is composed mainly of pre-Jurassic metamorphic rocks. Only the “Dorsal” and the Malaguide domains include fossiliferous Jurassic successions, as in Sierra Espuña (SE Spain), which is one of the bigger and well-exposed Jurassic outcrops of the Internal Zones. Collected Ammonite assemblages update and improve the precision of previous biostratigraphic data by the recognition of: the Domerian (= Upper Pliensbachian, in the Mediterranean Domain) Lavinianum (Cornacaldense Subzone), Algovianum (Ragazzoni, Bertrandi, Accuratum and Levidorsatum Subzones) and Emaciatum (Solare and Elisa Subzones) Zones; the Lower Toarcian Polymorphum and Serpentinum Zones; the Middle Toarcian, Bifrons and Gradata Zone; the Upper Toarcian Reynesi Zone; the Lower/Upper Bajocian, the Lower Callovian Bullatus and Gracilis Zones; the Middle/Upper Oxfordian Transversarium, Bifurcatus, Bimammatum and Planula Zones; and the Lower and Upper Kimmeridgian Platynota, Strombecki, Divisum and Beckeri Zones.The paleoenvironmental evolution of the Malaguide Jurassic at Sierra Espuña shows similarities with other Mediterranean Tethyan paleomargins. The biostratigraphic precision along with the litho- and biofacies analyses has enabled the interpretation that the Malaguide paleomargin evolved as a passive margin, developing shallow carbonate platforms, until the Domerian (Lavinianum Zone). Then, the platform broke up (Domerian, Lavinianum Zone-Upper Toarcian, Reynesi Zone) with the beginning of the rifting stage, beginning the development of horst-graben systems and the coeval drowning of the area. This stage ended in the upper Lower Callovian (Gracilis Zone) to the Middle Oxfordian (Transversarium Zone) interval, starting the drifting stage, which accentuated the horst-graben systems, leading to the deposition of condensed nodular limestones in the raised sea bottom.     

Microbial biofilms and the preservation of the Ediacara biota

Laflamme, M., Schiffbauer, J.D., Narbonne, G.M., & Briggs, D.E.G. 2011: Microbial biofilms and the preservation of the Ediacara biota. Lethaia, Vol. 44, pp. 203–213. The terminal Neoproterozoic Ediacaran Period is typified by the Ediacara biota (ca. 579–542 Ma), which includes the first morphologically complex macroscopic organisms. Both the taphonomic setting that promoted the preservation of the soft‐bodied Ediacara biota in coarse‐grained sediments, and the influence of associated microbial coatings on this process, have generated debate. Specimens of Ediacaran discs (Aspidella) from the Fermeuse Formation of Newfoundland, Canada, were analysed using environmental scanning electron microscopy (ESEM) and focused ion beam electron microscopy (FIB‐EM) to determine the relationship between the fossil specimens and the surrounding sediment. The presence of chemically distinct (Al–Mg–Fe–K‐ and to a lesser extent S‐rich), finer‐grained sediment (with organized iron sulphides) surrounding the upper and lower margins of the Ediacaran fossils is consistent with elemental analyses of well preserved bacterial biofilms from other localities. ESEM analyses reveal a contrast in the composition of the sediment bound within the discs, which contains a higher concentration of Al, Ca and K, and the purer Si‐rich sediment that forms the surrounding matrix. This suggests that the coarse grained sediment was incorporated into the organism during life. Ediacaran discs were likely surrounded by a bacterial biofilm or thin microbial mat composed primarily of extracellular polymeric substances (or exopolysaccharide) during life, which added structural stability to these frond holdfasts, and facilitated their fossilization. Microbially mediated preservation in Fermeuse‐style Ediacaran taphonomy provides an explanation for the dominance of Aspidella holdfasts in these settings, and suggests that preservation of Ediacaran fossils in the round may be much more prevalent than previously recognized. We suggest that the overwhelming dominance of circular to bulbous forms such as Aspidella in Ediacaran biotas around the world is a direct result of the interplay between microbial ecology and microbially mediated taphonomy. □Aspidella, Ediacaran preservation, environmental scanning electron microscopy, focused ion beam electron microscopy, palaeoecology, taphonomic bias.     

Origin and early diversification of the phylum Cnidaria Verrill: major developments in the analysis of the taxon's Proterozoic–Cambrian history

Diploblastic eumetazoans of the phylum Cnidaria originated during the Neoproterozoic Era, possibly during the Cryogenian Period. The oldest known fossil cnidarians occur in strata of Ediacaran age and consist of polypoid forms that were either nonbiomineralizing or weakly so. The oldest possible anthozoans, including the genus Ramitubus, may be related to tabulate corals and occur in the Doushantuo Lagerstätte (upper Doushantuo Formation, South China), the age of which is poorly constrained (approximately 585 Ma?). Conulariid scyphozoans may first appear as early as 635–577 Ma (Lantian Formation, South China). A definite conulariid, most similar to Palaeozoic species assigned to the genus Paraconularia, occurs in association with the possible scyphozoan, Corumbella werneri, in the latest Ediacaran (c. 543 Ma) Tamengo Formation of Brazil. Basal Cambrian (c. 540 Ma) phosphorites in the upper Kuanchuanpu Formation (South China) yield solitary polyps of the oldest probable anthozoan (Eolympia pediculata), which appears to have been a stem hexacorallian. This same formation contains fossils interpreted by some authors as pentaradial cubozoan polyps; however, both the oldest known cubozoans and the oldest hydrozoans, all medusae, may actually occur in the Cambrian (Series 3, c. 505 Ma) Marjum Formation (Utah, USA). Although these recently published palaeontological data tend to corroborate the hypothesis that Cnidaria has a relatively deep Neoproterozoic history, the timing of major internal branching events remains poorly constrained, with, for example, the results of some molecular clock analyses indicating that the two cnidarian subphyla (Anthozoaria and Medusozoa) may have originated as many as one billion years ago. Further progress towards elucidating the evolution and early fossil record of cnidarians may accrue from: (1) an intensive search for phosphatized soft parts in possible anthozoans from the Ediacaran Doushantuo Formation; (2) an expanded search for Ediacaran conulariids; and (3) additional detailed analyses of the taphonomy and preservation of Ediacaran and Cambrian cnidarians, including possible pentaradial cubozoan polyps from the Fortunian upper Kuanchuanpu Formation.     

Evolution of pelagic swells from hardground analysis (Bathonian–Oxfordian, Eastern External Subbetic, southern Spain)

The Middle Bathonian to Middle Oxfordian interval in the Eastern External Subbetic (Betic Cordillera, SE Spain) is characterized by Ammonitico Rosso facies including various stratigraphic breaks. Five hardground-bounded units are recognized in relation to hiatuses in the ammonite record at the following stratigraphic boundaries: Hg1 (Lower–Middle Bathonian), Hg2 (Middle–Upper Bathonian), Hg3 (Lower–Middle Callovian), Hg4 (Middle–Upper Callovian), and Hg5 (Callovian–Oxfordian). Interesting features of these hardgrounds include their microfacies, ferruginous crusts and macro-oncoids, taphonomy of macroinvertebrates, trace fossils, neptunian dykes, and the hiatuses associated with each of them. The main hardgrounds (Hg1, Hg2, and Hg5) contain trace fossils of the Cruziana and Trypanites ichnofacies as well as abundant fossil macroinvertebrates with taphonomic features evidencing corrasion, early diagenesis, and reworking, indicating substrate evolution from softground to hardground. Neptunian dykes affected the trace fossils and ammonoid moulds, and their walls and the hardground surfaces were colonized by ferruginous microbial crusts. These features are characteristic of the External Subbetic pelagic swells, where the absence of sedimentation, sediment bypassing and erosion, and early diagenesis during relative sea-level falls produced hardgrounds. The neptunian dykes are indicative of tectonic activity in the areas of pelagic swells. Ferruginous crusts and macro-oncoids developed only on hardground surfaces and neptunian dykes walls prior to deposition of condensed bioclastic beds, which are interpreted as the first deposits after hardground development and are related to the onset of transgression. The varying ranges of the gaps as well as lateral facies changes are related to different local paleobathymetry controlled by the activity of listric faults.     

Mesoproterozoic surface oxygenation accompanied major sedimentary manganese deposition at 1.4 and 1.1 Ga

Manganese (Mn) oxidation in marine environments requires oxygen (O₂) or other reactive oxygen species in the water column, and widespread Mn oxide deposition in ancient sedimentary rocks has long been used as a proxy for oxidation. The oxygenation of Earth's atmosphere and oceans across the Archean-Proterozoic boundary are associated with massive Mn deposits, whereas the interval from 1.8–1.0 Ga is generally believed to be a time of low atmospheric oxygen with an apparent hiatus in sedimentary Mn deposition. Here, we report geochemical and mineralogical analyses from 1.1 Ga manganiferous marine-shelf siltstones from the Bangemall Supergroup, Western Australia, which underlie recently discovered economically significant manganese deposits. Layers bearing Mn carbonate microspheres, comparable with major global Mn deposits, reveal that intense periods of sedimentary Mn deposition occurred in the late Mesoproterozoic. Iron geochemical data suggest anoxic-ferruginous seafloor conditions at the onset of Mn deposition, followed by oxic conditions in the water column as Mn deposition persisted and eventually ceased. These data imply there was spatially widespread surface oxygenation ~1.1 Ga with sufficiently oxic conditions in shelf environments to oxidize marine Mn(II). Comparable large stratiform Mn carbonate deposits also occur in ~1.4 Ga marine siltstones hosted in underlying sedimentary units. These deposits are greater or at least commensurate in scale (tonnage) to those that followed the major oxygenation transitions from the Neoproterozoic. Such a period of sedimentary manganogenesis is inconsistent with a model of persistently low O₂ throughout the entirety of the Mesoproterozoic and provides robust evidence for dynamic redox changes in the mid to late Mesoproterozoic.     

Stratigraphie et sédimentologie des « Couches rouges » continentales du Jurassique-Crétacé du Haut Atlas central (Maroc) : implications paléogéographiques et géodynamiques

In several synclines of the central High Atlas, the “Redbeds” following the closure of the marine Tethyan Atlasic trough during the Middle Jurassic are constituted by three successive formations or units of continental deposits dated recently with biostratigraphical elements. Some micropaleontological markers, mainly charophytes and ostracods, allow to precise the stratigraphy in agreement with a Bathonian-?Callovian assignment for the lower unit (Guettioua Formation), and in dating the middle and upper units. The Upper Jurassic, mainly the Kimmeridgian, is developed in the lower part of the middle unit (Iouaridene Formation). The Barremian has been recognized in this middle unit and in the upper unit (Jbel Sidal Formation). The Jurassic/Cretaceous boundary is thus delimited for the first time with micropaleontological data. These new data are very significant for the Atlasic history during the Mesozoic. The basaltic flows inserted in the continental Jurassic-Cretaceous deposits of the central High Atlas result from two separate events in the Middle Jurassic and in the Barremian. The tectogenesis in the basins is characterized by a polyphase process including notably a synsedimentary tectonic activity conspicuous in the Barremian. The evidence of marine to brackish intercalations allows moreover to date the first Cretaceous transgressive event on the NW boundary of the High Atlas during the Lower Barremian and to consider an Atlantic paleogeographical interaction. SW margin of the Tethyan trough in the Lower and Middle Jurassic, the central High Atlas is merged with the margin of the central Atlantic Ocean during the Lower Cretaceous.     

Précisions biostratigraphiques nouvelles sur le Berriasien des Djebel Nara et Sidi Kralif (Tunisie centrale)

The biostratigraphy of Sidi Kralif formation is precised by means of correlation of calpionellid, ostracod and ammonite faunas in three sections of Nara Mountain (Central Tunisia). The Upper Tithonian (Jacobi zone pars) and the Lower Berriasian (Grandis zone) show 40 m of pelagic sediments above the Nara dolomitic formation. The Middle Berriasian (Occitanica zone) under the same facies points out variations of thickness (60 to 100 m). Only the lower part of the Upper Berriasian (Paramimounum subzone) is present at the upper part with neritic facies (bioclastic limestones, sandstones, dolomites, breccia) and some changes of thickness (10 to 100 m). With the Upper Berriasian begins the thick detritic Meloussi formation.     

Animal resources and subsistence strategies

Several faunal assemblages excavated in deposits of different antiquity (from Lower Paleolithic to Bronze Age), located in Northern, Central and Southern Italy, were studied from the archeozoological and taphonomic point of view. Data obtained by different Authors allow reconstruction of subsistence strategies adopted by prehistoric humans in these areas and through time, in particular as far as the exploitation of animal resources is concerned. The following assemblages were considered: Isernia La Pineta (Molise; Lower Paleolithic), Grotta Breuil (Latium; Middle Paleolithic), Grotta della Ghiacciaia (Verona; Middle Paleolithic), Riparo di Fumane and Riparo Tagliente (Verona; Middle and Upper Paleolithic), Riparo Mochi (Liguria; Upper Paleolithic), Grotta della Continenza (L'Aquila; Upper Paleolithic and Mesolithic), Grotta dell'Edera (Trieste; Mesolithic and Neolithic), Grotta della Cala at Marina di Camerota (Salerno; Eneolithic), Contraguda (Sassari; Neolithic), Castellaro Lagusello (Mantova; Bronze Age). Exploitation of the vegetal resources has been analyzed in the Neolithic sites of Colle Santo Stefano (Fucino), Settefonti (L'Aquila) and Catignano (Pescara).     

Geographic views of human development

Human development can be divided into three stages: human ancestors (Lower Palaeolithic), early human races (Middle Palaeolithic) and modern humans (Upper Palaeolithic). Regional differentiation has been detected in the Lower Palaeolithic and is strongly developed in the Middle Palaeolithic but continues into the Upper Palaeolithic less marked. Clearly mixture at all levels accounts for this. Early humans absorbed the pre-existing regionalizations even as they further differentiated. Modern humans resulted from Upper Palaeolithic people spreading across the world and again absorbing the previous differentiations.     

Eine neueOtarion-Art (Trilobita, Arthropoda) aus dem Greifensteiner Kalk (unteres Mittel-Devon, Unter-Eifelium) von Greifenstein bei Herborn (Hessen, Deutschland)

en|This paper deals with a new species ofOtarion [Otarion (Otarionella) greifensteinen.se n. sp.] from the ‘Greifenstein Limestone’ of the ‘Wiege’ near Greifenstein, close to the village Greifenstein near Herborn (Lahn-Dill area, Hesse, Germany), which is described, figured and compared with all known species of this subgenus. It is a typical trilobite of the hercynian-bohemian shallow marine facies near the Lower-/Middle Devonian boundary (Upper Emsian / Lower Eifelian), which extends up into the lower part of the Middle Devonian (Lower Eifelian). The trilobites are transported for short distances only and, thus, are parautochthonous elements of the Greifenstein Facies.