Vegetation, climate and palaeoaltitude reconstructions of the Eastern Alps during the Miocene based on pollen records from Austria, Central Europe

Aim To reconstruct the flora, vegetation, climate and palaeoaltitude during the Miocene (23.03–5.33 Ma) in Central Europe. Location Six outcrop sections located in different basins of the Central Paratethys in Austria. Methods Pollen analysis was used for the reconstruction of the vegetation and climate. The altitude of the Eastern Alps that are adjacent to the Alpine Foreland and Vienna basins has been estimated using a new quantification method based on pollen data. This method uses biogeographical and climatological criteria such as the composition of the modern vegetation belts in the European mountains and Miocene annual temperature estimates obtained from fossil pollen data. Results Pollen changes from Early to Late Miocene have been observed. The vegetation during the Burdigalian and Langhian (20.43–13.65 Ma) was dominated by thermophilous elements such as evergreen trees, typical of a present‐day evergreen rain forest at low altitudes (i.e. south‐eastern China). During the Serravallian and Tortonian (13.65–7.25 Ma) several thermophilous elements strongly decreased, and some disappeared from the Central European region. This kind of vegetation was progressively substituted by one enriched in deciduous and mesothermic plants. Middle‐altitude (Cathaya, Cedrus and Tsuga) and high‐altitude (Abies and Picea) conifers increased considerably during the Langhian and later on during the Serravallian and Tortonian. Main conclusions Pollen changes are related to climatic changes and to the uplift of the Alpine massifs. The vegetation during the Burdigalian and Langhian reflects the Miocene climatic optimum. The decrease in thermophilous plants during the Serravallian and Tortonian can be interpreted as a climatic cooling and can be correlated with global and regional climatic changes. This study shows that the palaeoaltitude of the eastern part of the Eastern Alps during the Burdigalian was not high enough for Abies and Picea to form a forest. Therefore, we inferred that the summits of most of the mountains would have been less than 1800 m. The substantial increase of middle‐ and high‐altitude conifers in the pollen spectra suggests that the uplift rate increased during the Langhian in this region. Based on higher palaeoaltitude estimations for the pollen floras from the studied sections of Austria, we infer that the uplift of the easternmost part of the Alpine chain continued during the Serravallian and Tortonian.     

Benthic foraminiferal response to the emergence of the Isthmus of Panama and coincident paleoceanographic changes

Late Cenozoic benthic foraminiferal faunas from the Caribbean Deep Sea Drilling Project (DSDP) Site 502 (3052 m) and East Pacific DSDP Site 503 (3572 m) were analyzed to interpret bottom-water masses and paleoceanographic changes occurring as the Isthmus of Panama emerged. Major changes during the past 7 Myr occur at 6.7–6.2, 3.4, 2.0, and 1.1 Ma in the Caribbean and 6.7–6.4, 4.0–3.2, 2.1, 1.4, and 0.7 Ma in the Pacific. Prior to 6.7 Ma, benthic foraminiferal faunas at both sites indicate the presence of Antarctic Bottom Water (AABW). After 6.7 Ma benthic foraminiferal faunas indicate a shift to warmer water masses: North Atlantic Deep Water (NADW) in the Caribbean and Pacific Deep Water (PDW) in the Pacific. Flow of NADW may have continued across the rising sill between the Caribbean and Pacific until 5.6 Ma when the Pacific benthic foraminiferal faunas suggest a decrease in bottom-water temperatures. After 5.6 Ma deep-water to intermediate-water flow across the sill appears to have stopped as the bottom-water masses on either side of the sill diverge.The second change recorded by benthic foraminiferal faunas occurs at 3.4 Ma in the Caribbean and 4.0-3.2 Ma in the Pacific. At this time the Caribbean is flooded with cold AABW, which is either gradually warmed or is replaced by Glacial Bottom Water (GBW) at 2.0 Ma and by NADW at 1.1 Ma. These changes are related to global climatic events and to the depth of the sill between the Caribbean and Atlantic rather than the rising Isthmus of Panama. Benthic foraminiferal faunas at East Pacific Site 503 indicate a gradual change from cold PDW to warmer PDW between 4.0 and 3.2 Ma. The PDW is replaced by the warmer, poorly oxygenated PIW at 2.1 Ma. Although the PDW affects the faunas during colder intervals between 1.4 and 0.7 Ma, the PIW remains the principal bottom-water mass in the Guatemala Basin of the East Pacific.     

Climatic control on vegetation and sedimentary dynamics during the Miocene (Burdigalian to Langhian) in northeastern Tunisia

Palynological and sedimentological analyses were performed on Miocene sediments of North-East Tunisia in order to detect the changes in depositional environments, including those linked to eustasy, along with changes in vegetation and climate. The specific integration of palynological (pollen and dinocysts) and sedimentological (including facies analysis) data indicate that shallow marine settings persisted until the early Burdigalian–Langhian, and that open marine environments developed progressively in the late Langhian. Since the early Serravallian, deltaic environments developed under a fluctuating, but predominantly warm climate. The palynological data support a subtropical climate during the Burdigalian, with tropical conditions prevailing at the Langhian–Serravallian transition. The observed high frequency values of megathermic and mega-mesothermic pollen taxa represent the vegetation response to the Miocene climatic optimum (MCO).     

The bioeroded megasurface of Oura (Algarve,south Portugal): implications for the Neogene stratigraphy and tectonic evolution of southwest Iberia

The use of rocky palaeoshore bioerosion analysis as a tool to solve stratigraphic and tectonic issues is beginning to bear fruits. The occurrence of an extensive intra-Miocene marine abrasion platform in southern Portugal at Oura (Albufeira) has been identified on the basis of bioerosion trace fossils analysis. The observed ichnodiversity is rather low, with bivalve boring Gastrochaenolites being dominant. Nevertheless, the ichnoassemblage may be assigned to the Entobia ichnofacies. The palaeoichnological study of the Oura hardground confirmed the existence of an important intra-Miocene stratigraphic gap (ca. 3 Ma hiatus), represented by a razor-sharp erosional contact that separates the two main Neogene units in the Algarvian region: the lower carbonate sequence of Lagos–Portimão Formation (Langhian/Serravallian) and the upper siliciclastic sequence of the Cacela Formation (Upper Tortonian).     

Holoplanktonic gastropoda (Mollusca) from the Miocene of Cyprus: systematics and biostratigraphy

Abstract: Eleven randomly chosen outcrops in the Miocene Pakhna Formation of Cyprus were sampled for holoplanktonic Mollusca. Four species of Heteropoda were found, and 24 of Pteropoda, a substantial increase from the two species recorded until now from the Miocene of Cyprus. One pteropod species, Peracle charlotteae sp. nov. (Gastropoda, Pseudothecosomata), is introduced. Age assignments based on holoplanktonic molluscs for the 11 localities are as follows: Langhian (Alassa 1–4), (Serravallian?) Tortonian to Messinian (Episkopi 1), Tortonian (Agios Tychon, Tokhni and the Maroni Marlstone of Khirokitia 1–2) and Tortonian to Early Messinian (Episkopi 2). These age determinations in some cases are at odds with those from previous publications based on calcareous nannofossils and Foraminifera. The sediments underlying the Amathus Channel outcrop yielded insufficient fauna for definitive dating, but we suggest are younger than Late Serravallian. At some localities, particularly in the Alassa area, pteropod assemblages are strongly variable on a bed‐by‐bed basis, and this offers possibilities for future refined biostratigraphical interpretations. This is the first substantial holoplanktonic mollusc fauna described from the eastern Mediterranean basin and allows correlation with assemblages in the central Mediterranean and elsewhere.     

The potential of carbonate ramps to record C‐isotope shifts: insights from the upper Miocene of the Central Mediterranean area

The late Miocene is a crucial interval for global climate evolution as well as for the regional geodynamic evolution of the Central Mediterranean area. It spans the transition from the warm Mid Miocene Climatic Optimum, associated with the major Monterey Carbon Isotope Excursion, to the cooler Pliocene, characterized by a bipolar glaciation. Within this climatic transition, during the early Tortonian, a positive carbon isotope excursion related to a global carbon cycle perturbation is recorded, named Carbon Maximum 7 (CM7). In this study, two upper Serravallian–lower Tortonian carbonate ramps of the Central Mediterranean have been analysed: the Latium‐Abruzzi and the Apula ramps (Central Apennines, Central Italy). Carbon isotope ratios have been coupled with facies and microfacies analyses with the aims: (1) to identify the CM7 in the Central Mediterranean carbonate ramp successions; (2) to evaluate potential carbonate factory changes or demises related to the CM7; and (3) to discriminate the role of global vs regional factors in affecting the Mediterranean carbonate ramps. The two studied ramps show different evolutions due to regional geodynamics causes. The Latium‐Abruzzi ramp drowns in the Tortonian, while the Apula shows a regressive trend, with upper Tortonian middle ramp facies overlying the lower Tortonian outer ramp. Despite the complex geodynamic setting, a positive carbon isotope shift has been identified in both ramps and correlated with the CM7. This positive carbon isotope shift may be linked to the strengthening of the global ocean circulation during the late Miocene cooling. This strengthening of the circulation enhanced the coastal upwelling, bringing nutrient‐rich waters to the surface and triggering an enhanced primary productivity consistent with the CM7.     

Integrated stratigraphy and astronomical calibration of the Serravallian/Tortonian boundary section at Monte Gibliscemi (Sicily, Italy)

Results are presented of an integrated stratigraphic (calcareous plankton biostratigraphy, cyclostratigraphy and magnetostratigraphy) study of the Serravallian/Tortonian (S/T) boundary section of Monte Gibliscemi (Sicily, Italy). Astronomical calibration of the sedimentary cycles provides absolute ages for calcareous plankton bio-events in the interval between 9.8 and 12.1 Ma. The first occurrence (FO) of Neogloboquadrina acostaensis, usually taken to delimit the S/T boundary, is dated astronomically at 11.781 Ma, pre-dating the migratory arrival of the species at low latitudes in the Atlantic by almost 2 million years. In contrast to delayed low-latitude arrival of N. acostaensis, Paragloborotalia mayeri shows a delayed low-latitude extinction of slightly more than 0.7 million years with respect to the Mediterranean (last occurrence (LO) at 10.49 Ma at Ceara Rise; LO at 11.205 Ma in the Mediterranean). The Discoaster hamatus FO, dated at 10.150 Ma, is clearly delayed with respect to the open ocean. The ages of D. kugleri first and last common occurrence (FCO and LCO), Catinaster coalitus FO, Coccolithus miopelagicus last (regular) occurrence (L(R)O) and the D. hamatus/neohamatus cross-over, however, are in good to excellent agreement with astronomically tuned ages for the same events at Ceara Rise (tropical Atlantic), suggesting that both independently established timescales are consistent with one another. The lack of a reliable magnetostratigraphy hampers a direct comparison with the geomagnetic polarity timescale of Cande and Kent (1995; CK95), but ages of calcareous nannofossil events suggests that CK95 is significantly younger over the studied time interval. Approximate astronomical ages for the polarity reversals were obtained by exporting astronomical ages of selected nannofossil events from Ceara Rise (and the Mediterranean) to eastern equatorial Pacific ODP Leg 138 Site 845, which has a reliable magnetostratigraphy.Our data from the Rio Mazzapiedi–Castellania section reveal that the base of the Tortonian stratotype corresponds almost exactly with the first regular occurrence (FRO) of N. acostaensis s.s. as defined in the present study, dated at 10.554 Ma. An extrapolated age of 11.8 Ma calculated for the top of the Serravallian stratotype indicates that there is a gap between the top of the Serravallian and the base of the Tortonian stratotype, potentially rendering all bio-events in the interval between 11.8 and 10.554 Ma suitable for delimiting the S/T boundary. Despite the tectonic deformation and the lack of a magnetostratigraphy, Gibliscemi remains a candidate to define the S/T boundary by means of the Tortonian global boundary stratotype section and point (GSSP).     

Depositional environment changes during the early–late Serravallian boundary dated by the Central Paratethys bioevents

The early–late Serravallian boundary (Badenian–Sarmatian) is a key interval for understanding Central Paratethys evolution. Environmental changes resulted in a great regional faunal turnover known as the Badenian-Sarmatian extinction event (BSEE). Here, we present a high-resolution sedimentological and biostratigraphical study from a rare site located on the Vienna and Danube basin junction (Slovakia). Four Middle Miocene depositional cycles/episodes ranked between 13.1 and 12.6 Ma are described in detail: (1) early Serravallian (13.1 Ma or older) shallow-marine episode; (2) early Serravallian (Badenian; Bulimina–Bolivina biozone; ~13.1 Ma or younger) outer shelf cycle; (3) late Serravallian (Sarmatian; large Elphidia biozone; ~12.6 Ma or younger) inner shelf cycle; (4) late Serravallian? A sedimentary episode represented by a scour filled with a reworked Serravallian (Upper Badenian and Sarmatian) material. The middle Miocene strata are overlaying and discordantly separated by Quaternary fluvial (floodplain) sediments (2.58 Ma or younger). These episodes reflect the early–late Serravallian turnover documented in the bioevents and in the sedimentological record.     

Change in diversity,ecological significance and biogeographical relationships of the Mediterranean Miocene toothed whale fauna

The main evolutionary trend in the Mediterranean Miocene toothed whale fauna is related (1) to the change in diversity and (2) to the turnover in community structure. Diversity increases from Upper Aquitanian–Lower Burdigalian to Burdigalian–Langhian, when it reaches its maximum. Starting from this time, diversity decreases progressively. The Early Miocene (Upper Aquitanian–Lower Burdigalian) Mediterranean toothed whale fauna, as well as the extramediterranean ones, is characterised by a high number of endemic taxa and by the prevalence of longirostral forms living in estuarine-neritic environments. A more diversified fauna spreading in neritic and pelagic environments characterises the Burdigalian–Langhian age, while an increase in pelagic forms and the nearly complete disappearance of some archaic longirostral taxa is typical of the Serravallian–Messinian fauna. Decrease in diversity and disappearance of archaic longirostral taxa are also recorded, at more general scale, in the Late Miocene extramediterranean fossil bearing deposits. These events can be related to the progressive global climatic deterioration, starting from Middle Miocene. From a biogeographic point a view, we can outline some relationships between the Mediterranean and western North Atlantic Miocene faunas. Closer affinities are observed between the Baltringen fauna and the northern Atlantic one, because of the presence of the genera Pomatodelphis and Zarhachis (platanistids) in both areas. In the Miocene Mediterranean and in North Atlantic, the delphinids are apparently absent as well as other extant delphinoid groups even if erroneously recorded in the past.     

Paleoenvironmental evolution of the eastern Mediterranean during the Messinian: Constraints from integrated microfossil data of the Pissouri Basin (Cyprus)

Integrated data of calcareous nannofossils, as well as planktonic and benthic foraminifera from the Pissouri Motorway section on Cyprus allow the reconstruction of surface- and bottom-water paleoenvironments of the eastern Mediterranean during the interval preceding the Messinian salinity crisis (MSC). Contrary to deeper-water locations, where benthic foraminifera faunas are suppressed or absent just after the Tortonian–Messinian boundary, sediments deposited at intermediate water depths do contain benthic assemblages. From the earliest Messinian onwards, a development towards increasingly unfavourable paleoenvironments is reflected in the planktonic and benthic microfossil records of the Pissouri section and proceeds with rather discrete time steps that can be correlated to sequences throughout the Mediterranean. Shortly after the Tortonian–Messinian boundary a transition is recorded in the sedimentology and the open marine, deeper-water taxa disappear from the benthic foraminifera assemblages; subsequently, the diversity of all fauna groups diminishes. The changes recorded at species level in both surface-water and sea-floor dwelling taxa suggest decreasing circulation of the bottom waters, associated with changes in the surface waters, most likely due to increasing stratification. From ∼6.73 Ma onwards, our data indicate a prominent change to more restricted conditions and increasing salinity at the sea floor together with intermittently rising surface water salinity. The dominance of oligotypic and monospecific assemblages and the frequent shifts in assemblage compositions of all microfossil groups indicate severely stressed environments after ∼6.4 Ma, probably related to increased salinity. The major changes in paleoenvironmental conditions, including oxygen deprivation due to stagnation and hypersalinity, can be explained by hydrographical changes in the Mediterranean basin, which are probably caused by tectonic movements in the Rif Corridor acting in concert with astronomical cyclicity. Evaluation of the paleodepth proxies indicates that the depth of the Pissouri Basin remained rather constant at ∼300–500 m, with a minimum of 200 m, until deposition of the “barre jaune”, the transitional interval towards the evaporites and that early shallowing to neritic depths, as was proposed before, is highly unlikely.     

Late Neogene planktonic foraminifera of the Cibao Valley (northern Dominican Republic): Biostratigraphy and paleoceanography

An assemblage of planktonic foraminifera is described from 125 samples taken from the Cercado, Gurabo, and Mao Formations in the Cibao Valley, northern Dominican Republic. The primary objectives of this study are to establish a biochronologic model for the late Neogene of the Dominican Republic and to examine sea surface conditions within the Cibao Basin during this interval. The Cercado Formation is loosely confined to Zones N17 and N18 (∼ 7.0–5.9 Ma). The Gurabo Formation spans Zones N18 and N19 (∼ 5.9–4.5 Ma). The Mao Formation is placed in Zone N19 (∼ 4.5–3.6 Ma). Changes in the relative abundances of indicator species are used to reconstruct sea surface conditions within the basin. Increasing relative abundances of Globigerinoides sacculifer and Globigerinoides ruber, in conjunction with a decreasing relative abundance of Globigerina bulloides, suggests the onset of increasing sea surface temperature and salinity in conjunction with diminishing primary productivity at ∼ 6.0 Ma. Abrupt increases in the relative abundances of G. sacculifer and G. ruber at ∼ 4.8 Ma suggest a major increase in sea surface temperature and salinity in the early Pliocene. The most likely mechanism for these changes is isolation of the Caribbean Ocean through progressive restriction of Pacific–Caribbean transfer via the Central American Seaway. Periods of high productivity associated with upwelling events are recorded in the upper Cercado Formation (∼ 6.1 Ma) and in the middle Mao Formation (∼ 4.2 Ma) by spikes in G. bulloides and Neogloboquadrina spp. respectively. The timing of major increases in sea surface salinity and temperature as well as decreasing productivity (∼ 4.8 Ma) and periods of upwelling (∼ 6.1and 4.2 Ma) in the Cibao Basin generally corroborate previously suggested Caribbean oceanographic changes related to the uplift of Panama. Changes in sea surface conditions depicted by paleobiogeographic distributions in the Cibao Basin suggest that shoaling along the Isthmus of Panama had implications in a shallow Caribbean basin as early as 6.0 Ma. Major paleobiologic changes between ∼ 4.8 and 4.2 Ma likely represent the period of final closure of the CAS and a nearly complete disconnection between Pacific and Caribbean water masses. This study illustrates the use of planktonic foraminifera in establishing some paleoceanographic conditions (salinity, temperature, productivity, and upwelling) within a shallow water basin, outlining the connection between regional and localized oceanographic changes.     

Les Pectinidae miocènes des faluns (Ouest de la France). Intérêts biostratigraphiques des associations

The Miocene Pectinidae from the “faluns” (W France). Biostratigraphical interests of the associations. New sampling was realized throughout neogene outcrops occurring in Western France (mainly, “faluns” of Langhian to Tortonian age from Touraine, Anjou and Blésois). It has been known for long that the species or associations of the representatives of the family Pectinidae vary in each outcrop, but it was still necessary to get original data, which were collected precisely in their original level. Such a work is still in progress in Mediterranean areas. It seems that the systematic framework of several species has still to be detailed; the recently re-discovered species may be 12 in number. The species may characterize four main assemblages: rich and poorly diversified faunas, collected in microconglomerates, deposited in shallow environments; rich and diversified association, corresponding to the bryozoa facies deposited in deeper environments (“savignean” facies Auct.); poor assemblage, collected in shallow water, shelly beds (“pontilevian” facies Auct.); nearly absent Pectinidae in the shallow water Arca facies (“lublean” Auct.). Generally, the species belonging to the genus Pecten are only common in the savignean facies, in which the diversity consequently increases. Actually, the biochronological framework of the “faluns” is correct, mainly related to the mammal zonation. The associations of Pectinidae collected in the “faluns” may be of several interests.

• •Several memberships of the observed faunas have a long stratigraphical range (Langhian–Pliocene), wide geographical distribution (from Britain to Mediterranean areas), and may be ecologically tolerant. They belong to the Crassadoma multistriata and Aequipecten radians species. In Western France, A. radians may be related to quite shallow environment. Opposite, the species Gigantopecten ligerianus may be related to the deepest environments.
• •Several species or association may success to each other through time, which may offer a regional stratigraphical interest, in the “faluns” from Western France: P. subarcuatus—P. sp. 1 (Langhian), P. sp. 2 (close to praebenedictus, Serravalian to Tortonian.), P. praebenedictus s. s. (younger Tortonien), P. jacoabeus or maximus (Messinian to Pliocene). G. ligerianus was recently recollected regionally in sediments of Langhian age only, if the local deposition environments are deep enough. Note that numerous shells belonging to this species exist in historical collections, from Doué area (obs. pers. M.B.).

     

The age of immigration of the vertebrate faunas found at Gargano (Apulia,Italy) and Scontrone (l’Aquila,Italy)

Recently a discussion is taking place about the Scontrone (l’Aquila) and Gargano (Apulia, Italy) mammal faunas and the age of their immigration. Mazza and Rustioni (2008) dated the Scontrone mammal fossils as Tortonian on the basis of their position in the Lithothamnium Limestone and came to the conclusion that some elements of the Scontrone and Gargano faunas must have colonised the area in Oligocene or Early Miocene times. Van den Hoek Ostende et al. (2009) disagreed with this interpretation and suggested a Late Miocene (10 Ma) age for the time of immigration. We think the arguments to place Scontrone in the Tortonian are not convincing. An analysis of the potential ancestors of each of the Gargano faunal components shows that a Messinian age for the immigration is fully compatible with the distribution of these ancestors in the European Miocene.     

Données nouvelles sur la stratigraphie du Miocènede St Florent (Corse)

Up to now the top of the marine miocenic sediments 0205 was thought to be white limestones, the so-called “molasses blanches, which stratigraphic position has been modified according to previous authors from the Langhian to Tortonian. We found, overlying the «molasses blanches, a thin marly-sandy formation very well dated of the top of the Langhian by microfauna and nannoplancton. This formation represents the most recent marine miocenic deposits known at this time in the St Florent basin.     

The origins and evolution of the North American grassland biome: the story from the hoofed mammals

The North American grassland biome first appeared around 18 Ma in the mid Miocene. The familiar story of the Neogene evolution of this biome is of the replacement of ungulates (hoofed mammals) having a primarily browsing diet by the more derived grazing ungulates. However, new data show a more complicated pattern of faunal succession. There was a maximum taxonomic diversity of ungulates at 16–14 Ma, including a large number of grazers, and the subsequent decline in overall diversity was largely due to the decline of the browsers, with little corresponding increase in the grazers. Additionally the mid Miocene faunas (∼18–12 Ma) contained a much greater number of browsers than any comparable present-day habitat. We discuss possible explanations for these non-analogous grassland faunas, including the possibility that the primary productivity of the vegetation was greater in the early to middle Miocene than it is today. One possible explanation for increased primary productivity is higher Miocene levels of atmospheric carbon dioxide than in the present day. The proposed difference in vegetational productivity also may explain why horses radiated as the main grazers in North America, in contrast to the radiation of antelope in the Plio–Pleistocene African grasslands.     

Biochronology and paleoclimatic implications of Middle Eocene to Oligocene planktic foraminiferal faunas

Planktic foraminiferal assemblages have been analyzed quantitatively in six DSDP sites in the Atlantic (Site 363), Pacific (Sites 292, 77B, 277), and Indian Ocean (Sites 219, 253) in order to determine the nature of the faunal turnover during Middle Eocene to Oligocene time. Biostratigraphic ranges of taxa and abundance distributions of dominant species are presented and illustrate striking similarities in faunal assemblages of low latitude regions in the Atlantic, Pacific and Indian oceans. A high resolution biochronology, based on dominant faunal characteristics and 55 datum events, permits correlation between all three oceans with a high degree of precision. Population studies provide a view of the global impact of the paleoclimatic and paleoceanographic changes occurring during Middle Eocene to Oligocene time.Planktic foraminiferal assemblage changes indicate a general cooling trend between Middle Eocene to Oligocene time, consistent with previously published oxygen isotope data. Major faunal changes, indicating cooling episodes, occur, however, at discrete intervals: in the Middle Eocene 44-43 Ma (P13), the Middle/Late Eocene boundary 41-40 Ma ( ), the Late Eocene 39-38 Ma ( ), the Eocene/Oligocene boundary 37-36 Ma (P18), and the Late Oligocene 31-29 Ma ( ). With the exception of the boundary, faunal changes occur abruptly during short stratigraphic intervals, and are characterized by major species extinctions and first appearances. The Eocene/Oligocene boundary cooling is marked primarily by increasing abundances of cool water species. This suggests that the boundary cooling, which marks a major event in the oxygen isotope record affected planktic faunas less than during other cooling episodes. Planktic foraminiferal faunas indicate that the boundary event is part of a continued cooling trend which began during the Middle Eocene.Two hiatus intervals are recognized in low and high latitude sections at the Middle/Late Eocene boundary and in the Late Eocene ( ). These hiatuses suggest that vigorous bottom water circulation began developing in the Middle Eocene, consistent with the onset of the faunal cooling trend, and well before the development of the psychrosphere at the boundary.     

The Early Pliocene re-colonisation of the deep Mediterranean Sea by benthic foraminifera and their pulsed Late Pliocene–Middle Pleistocene decline

Ninety-five species and 19 genera of cosmopolitan, deep-sea benthic foraminifera belonging to the families Pleurostomellidae, Stilostomellidae and Nodosariidae, became extinct during the Late Pliocene–Middle Pleistocene. Only 50% of these (44 species) were present in the Pliocene or Pleistocene of the deep Mediterranean Sea (ODP Sites 654, 966, 967, 975, 976), being those which had successfully migrated in via the Strait of Gibraltar from the deep Atlantic following the annihilation of the Mediterranean deep-sea fauna during the Late Miocene Messinian Crisis. Most colonisation occurred within the first 0.8 myrs (5.3–4.5 Ma) after re-establishment of the Mediterranean–Atlantic link, with possibly a second lesser period of immigration in the Late Pliocene (3.4–3.0 Ma). We infer that colonisations may have been fortuitous and few in number, as some common members of the group in the Atlantic never succeeded in establishing in the Mediterranean Sea. There is no evidence of any new immigration events during the Pleistocene, implying that the present anti-estuarine circulation may have been in place throughout this period. Our studies suggest that these deep-water, low-oxygen-tolerant foraminifera survived the many periods of deep-water sapropel formation in the Pliocene–Early Pleistocene, possibly in somewhat shallower (~ 500 m) refuges with dysoxic, rather than anoxic conditions.The Pliocene–Pleistocene stratigraphic record of this group of elongate, cylindrical benthic foraminifera with constricted and specialised apertures is similar in the west and east Mediterranean basins. The group declined in abundance (flux) and diversity in two pulses, during the Late Pliocene (3.1–2.7 Ma) and the late Early Pleistocene (1.3–1.0 Ma) in concert with global, southern-sourced, deep-water sites (AABW, CPDW) and earlier than the single decline (1.0–0.6 Ma) in global, intermediate water sites (uNADW, AAIW). All species, with one possible exception, disappeared earlier in the Mediterranean than globally. The highest occurrence of any species of this group in Mediterranean sites was 0.8–0.43 Ma, comparable with 0.7–0.2 Ma outside with the youngest survivors being in abyssal, deep-water.Thus, despite the unusual oceanographic conditions and isolation, the deep Mediterranean Sea was in this case neither the centre for the evolution of new species nor a refuge where species survived after they had disappeared elsewhere.     

Impact of the Middle Miocene climate transition on elongate,cylindrical foraminifera in the subtropical Pacific

Fifty-eight species of elongate, cylindrical benthic foraminifera (here referred to as the Extinction Group) belonging to genera that became extinct during the mid-Pleistocene Climate Transition (MPT), were documented (~ 50 kyr resolution) through the early middle Miocene (15–13 Ma) in two sites on opposite sides of the subtropical Pacific Ocean (ODP Sites 1146, South China Sea; ODP Site 1237, southeast Pacific). The study was undertaken to investigate the response of the Extinction Group (Ext. Gp) to the major cooling during the middle Miocene Climate Transition (MCT) to look for clues that might explain the causes of the extinction during the glacials of the mid-Pleistocene Climate Transition. Ext. Gp faunal differences between the two sites (attributed to regional and bathymetric differences in food supply to the seafloor) are greater than those that occurred through the 2 myr time span at either site. The middle Miocene Climate Transition was not an interval of enhanced species turnover or a decline in Ext. Gp abundance, in contrast to the major extinctions that occurred during the mid-Pleistocene Climate Transition. Distinct changes in the composition of the Ext. Gp faunas did occur through this time (more pronounced in Site 1237). At both sites the pre-middle Miocene Climate Transition faunas were transformed into their post-middle Miocene Climate Transition composition during the period of major cooling (14.0–13.7 Ma). During this transition interval the faunal composition swung back and forth between the two end member faunas. These faunal changes are attributed to changes in productivity (decrease in South China Sea, increase in southeast Pacific), brought about by major changes in global climate and continental aridity.     

Calcareous nannofossil biostratigraphy of the M. del Casino section (northern Apennines,Italy) and paleoceanographic conditions at times of Late Miocene sapropel formation

A detailed quantitative calcareous nannofossil analysis has been performed on 138 samples from the astronomically dated Monte del Casino section with the aim to identify and precisely date the most important calcareous nannofossil events across the Tortonian/Messinian boundary in the Mediterranean, and to unravel paleoceanographic conditions at times of sapropel formation during the Late Miocene. From the biostratigraphic perspective, the genus Amaurolithus provides three successive first occurrences (FOs): A. primus, A. cf. amplificus and A. delicatus, dated at 7.446, 7.434 and 7.226 Ma, respectively. Other bioevents include the base and top of the `small reticulofenestrids' Acme, dated at 7.644 and 6.697 Ma, and the FO, FCO and LO of R. rotaria, dated at 7.405, 7.226 and 6.771 Ma. These events appear to be useful in improving biostratigraphic resolution in the Tortonian–Messinian boundary interval, at least for the Mediterranean. Quantitative analysis revealed changes in the calcareous nannofossil assemblage associated with the sapropels. The observed fluctuations suggest a single mechanism for sapropel formation in the Mediterranean during the late Neogene. Sapropels are characterized by a decrease in the total number of coccoliths, interpreted mainly as a reduction in calcareous nannofossil production due to increased siliceous plankton production during spring blooms; and an increase in reworked specimens, interpreted to reflect enhanced continental input via river run-off. An increase in abundance of the genus Rhabdosphaera can be explained by opportunistic behavior at the end of the spring bloom when nutrient levels start to become impoverished. As far as sea surface water temperature indicators are concerned, warm water D. pentaradiatus shows positive fluctuations in sapropels while cooler water D. intercalaris and C. pelagicus show negative fluctuations.     

Biogeographic relationships of African carnivoran faunas, 7–1.2 Ma

This study analyses the carnivore component of African fossil faunas from three time slices: 7–5 Ma, 4–3 Ma, and 2.5–1.2 Ma, using cluster analysis and principal coordinate analysis (PCO) of presence/absence data on genera. The faunas mostly cluster by time slice, with the exception of Laetoli (Tanzania) and Ahl al Oughlam (Morocco), which differ from all other faunas. The separation during the Late Miocene of a Chado–Libyan bioprovince from the remainder of Africa is supported. No such distinctions are present in the other time slices. Taxonomic distance is not generally correlated with geographic distance, though if Langebaanweg is removed from the 7–5 Ma time slice, the correlation at that time is significant. Comparison of these paleontological results with phylogeographic studies of modern species leads to some general comments on the analytic power of the fossil record with regard to interregional migrations.