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High-Mg diorites and/or ultrapotassic volcanic rocks are generally associated with postcollisional porphyry copper deposits, but their contribution to the formation of the mineralization remains unclear. A suite of Miocene postcollisional ultrapotassic-potassic lamprophyres, high-Mg diorites, and adakite-like intrusions have been recognized in the Zhunuo porphyry Cu deposit, located in a continental collisional zone within the Gangdese belt, southern Tibet. The post-mineralization ultrapotassic-potassic lamprophyres have zircon U-Pb ages of 12.2±2.1 Ma and contain abundant Proterozoic to Miocene inherited zircons. The ultrapotassic lamprophyres have high K2O (>8.5wt%) and MgO (>8.8wt %) contents, are enriched in light rare earth elements (LREE; La=123 ppm) and large ion lithophile elements (LILE; e.g. Ba=3102 ppm, Th=116.6 ppm, and Pb=140 ppm), and display high Th/Yb and Rb/Sr, and low Ba/Rb and Hf/Sm ratios. They have zircon εHf(t) values of -2.8 to 1.3, δ18O values of 6.5 to 7.4%0', and enriched bulk-rock Sr-Nd-Pb isotope compositions ((87Sr/86Sr)i=0.73134, εNd(t)=-13.7, (206Pb/204Pb)i=19.20). Their parental magmas were derived from partial melting of an enriched mantle source that had been metasomatized by fluids and sediment-derived melts associated with Neo-Tethyan oceanic subduction and subsequent Indian continental lithosphere subduction. The potassic lamprophyres have lower contents of K2O, MgO, REE and LILE than the ultrapotassic lamprophyres and (87Sr/86Sr)i of 0.710993 to 0.711139, εNd(t) of -12.3 to -12.4, and (206Pb/204Pb)i of 18.59 to 18.72. Taken together with observations of a negative trend between eNd(t) and MgO content; positive trends between (87Sr/87Sr)i, (206Pb/204 Pb)i and MgO content from ultrapotassic lamprophyres to potassic lamprophyres; the existence of abundant Miocene inherited zircons showing similar ages and εHf(t) values to the adakite-like intrusions; and variable Hf/Sm ratios with some Hf/Sm ratios similar to adakite-like intrusions, we propose that the potassic lamprophyres were formed by mixing of ultrapotassic lamprophyre magmas with adakitelike magmas. The syn-mineralization high-Mg diorites including diorite porphyry and enclaves hosted by the adakite-like intrusions at Zhunuo have zircon U-Pb ages of 13.0±0.2 Ma and 13·1±0·2 Ma. They show negative correlations between Y, Yb, Dy/Yb and SiO2, and positive correlations between Sr, Sr/Y and SiO2, among which some more evolved samples (such as diorite porphyry) show adakite-like geochemical signatures. The high-Mg diorites are enriched in LREE and LILE, depleted in high-field-strength elements (HFSE), and have (87Sr/86Sr)i of 0·709401 to 0·710362, εNd(t) of -11·1 to -9·9, and (206Pb/204Pb)i of 18·62 to 18·71. Taken together with petrographic observations that show magma mixing, we argue that the high-Mg diorites were derived from previously subduction-modified Tibetan lithospheric mantle with little or no input from Indian continental sediment. Mixing with adakite-like magmas and fractional crystallization of hornblende and/or titanite are also responsible for the differentiation of the high-Mg diorites. The ore-hosting, adakitelike granitic rocks at Zhunuo with zircon U-Pb ages of 14·7±0·3 Ma and 14·6±0·2 Ma have lower concentrations of REE, LILE and HFSE, much higher εNd(t) (-6·1 to -6·9) and lower (87Sr/86Sr)i (0·707325-0·707663) values than the ultrapotassic lamprophyres and the high-Mg diorites. They were derived from remelting of previously subduction-modified Tibetan lower crust with some involvement of hydrous high-Mg dioritic magmas during magma mixing. The postcollisional adakite-like intrusions in the Gangdese belt could be generated by remelting of previously subduction-modified lower crust and mixing with hydrous high-Mg dioritic magmas in a lower crustal MASH zone and/or in an upper-crustal adakite-like magma chamber. The metallogenic potential of postcollisional adakite-like intrusions largely depends on rejuvenation of subductionmodified lower crust by previous arc magmas, differentiation of hydrous high-Mg dioritic magmas, and magma mixing of high-Mg dioritic magmas with lower crustal magmas. [ABSTRACT FROM AUTHOR]

Paenemarmota Hibbard and Schultz, 1948 includes 3 species of giant ground squirrels within Marmotini (Rodentia, Sciuridae) from the Late Miocene and Pliocene of central and western North America. We developed skeletal and dental models for estimating body mass across modern species of Marmotini and apply these models to Paenemarmota. The most reliable models for estimating body mass of modern species (on the basis of length and width of femur, lengths of p4 and P4) generally yielded lower estimates of body mass for Paenemarmota than less reliable models (on the basis of lengths of m1, m2, M1, and M2). Models that were most reliable across modem species yielded 2 nonoverlapping estimates for P. barbouri Hibbard and Schultz, 1948: 9.5-9.8 kg on the basis of femur dimensions, and 14.4-16.2 kg on the basis of lengths of premolars. On the basis of lengths of premolars, P. me.xicana (Wilson 1949) closely resembled P. barbouri in estimated mass (14.4-15.7 kg), but P. sawrockensis (Hibbard 1964) was smaller (10.0-12.4 kg). These large ground squirrels probably differed in mass-dependent biological attributes from all modern marmotines. [ABSTRACT FROM AUTHOR]

SUMMARY The separation of Northeast Greenland and Svalbard is the result of large-scale strike slip movements during Cenozoic times. Geological evidence for these movements can be found onshore both on North Greenland and Svalbard. However, the role of the submarine Yermak Plateau (YP) in this process is unclear. The compilation of available multichannel reflection and wide-angle seismic data give new insights into the sedimentary and crustal structure and evolution of the plateau. The flat surface of the present-day plateau is a quite young feature. Up to 2 km of Cenozoic sediments cover a rough basement, which show similarities to the rough topography and strike of geological structures of Spitsbergen Island. In some basins more than 4 km of sedimentary rocks could be mapped. The most pronounced structure is the Sverdrup Bank, which appears to be part of a larger crustal block. P-wave velocities of about 4.5 km s-1 derived from sonobuoy data indicate that its uppermost part is most probably composed of sedimentary or volcanic rocks. We have made a correlation of previously defined seismic units across the YP to outline the history of sediment deposition in the area. The existing graben structures on the plateau might have provided early shallow pathways for water exchange between the Arctic and the Atlantic Oceans. A chaotic sedimentary apron east of the Sverdrup Bank and bright reflections near the Mosby Seamount interpreted as magmatic sills suggest tectonic and magmatic events during the Miocene. [ABSTRACT FROM AUTHOR]

SUMMARY We present the evidence for an anomalous southwest-dipping slab in southern Mexico. The main evidence comes from a clear receiver function image along a seismic line across the Isthmus of Tehuantepec and is also supported by a previous global tomographic model. The slab dips at 35°, is approximately 250 km in length and appears to truncate the Cocos slab at about 120 km depth. We hypothesize that the slab was created by subduction of oceanic lithosphere prior to the collision of the Yucatán Block with Mexico at approximately 12 Ma. This scenario would explain the Chiapas Fold and Thrust Belt as the product of this collision, and its age constrains the date of the event to be in the Miocene. [ABSTRACT FROM AUTHOR]

SUMMARY High-grade metamorphic rocks of the upper amphibolite to granulite facies in the Higher Himalayan crystalline (HHC) were studied for their appropriateness for palaeomagnetic investigations. Sampling and fieldwork was accomplished on a south-north transect at ∼87°E in the Khumbu region south of Everest. Paragenesis of iron-sulphides and oxides was found to be variable due to different source rocks and metamorphic conditions in this area. Unblocking temperature ranges, isothermal remanence acquisition, low-temperature magnetic properties and microscopic observations confirm the presence of pyrrhotite and magnetite. Two remanence components were separated with unblocking temperature intervals of 250-330 °C and 370-550 °C, which can be attributed to characteristic remanent magnetizations (ChRM) of monoclinic pyrrhotite (ChRMpyr) and magnetite (ChRMmag), respectively. Mainly the ChRMpyr showed a consistent demagnetization behaviour, probably residing in pyrrhotite particles within the single domain to pseudo-single domain range. Normal and reverse polarities were observed, partly co-existing within the unblocking spectrum of single specimens; this (i) supports a thermoremanent (TRM) origin of the ChRMpyr and (ii) indicates that the time span of remanence acquisition was long enough to average out palaeosecular variation. The age of the ChRMpyr can be related to the last metamorphic cooling event at the Early to Late Miocene boundary (16 Ma). The ChRMmag is probably a secondary chemical or thermochemical remanence acquired by hydrothermal processes during retrogression. ChRMpyr and ChRMmag directions are similar suggesting that pyrrhotite and magnetite were magnetized approximately contemporaneously. Separation of the sampling area into three sectors reveals a south-north trend with (i) variable block rotations in the southernmost part close to the Main Central Thrust (five sites), (ii) no rotation in the area between Lukla and Namche (10 sites) and (iii) a significant clockwise rotation ( N= 5 sites, D/ I= 42.3°/29.4°, k= 20.7, α95= 17.2°) along the Imja Khola north of Namche. We interpret the clockwise rotation as an apparent rotation due to tilting by crustal doming in the Everest region. This doming obviously occurred north of a fault zone located at around Namche and was not affecting the region south of it. The clockwise sense of the apparent vertical-axis rotation indicates that the area north of Namche is located at the western side of the dome structure where westward tilting around a subhorizontal axis occurred (best fit: tilt direction 277°, tilt angle 51°). [ABSTRACT FROM AUTHOR]

Two biogeographical units are generally recognized in the present shelf area of Argentina: the Magellanian and Argentinian Provinces. The two provinces differ in their fossil record. The evolution of these provinces has been characterized by migrations, extinctions, pseudoextinctions and, perhaps, even speciation events. Marine vertebrate assemblages with some similarities to the Argentinian fauna were already present in the Miocene, whereas no associations similar to those of the Magellanian fauna have been found in South America before the Pleistocene. Two successive major marine transgressions flooded northern Patagonia during the Miocene: the 'Patagoniense' (Early Miocene) and the 'Entrerriense' (Middle to Late Miocene). We analyse three rich fossil assemblages that were formed during these transgressions. The absence of Magellanian Miocene vertebrate assemblages is consistent with the hypothesis of a more southern distribution of the cold-temperate fauna at that time. In Patagonia, as in other regions, an increased number of living groups appeared from the Lower to Upper Miocene. The Late Miocene aquatic mammals had a modern aspect, and some of the fish species are still living in the South Atlantic Ocean. In this contribution, we stress that warm-temperate fishes and a high diversity of penguins are found together at the base of the Gaiman Formation. We hypothesize that penguins were adapted to live in warmer waters than those of the latest Cenozoic and the Recent. Finally, we recall that many taxa became extirpated because of the global temperature drops of the late Cenozoic. However, some fishes and pinnipeds which were extirpated only in the Atlantic Ocean are discussed here. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, , 423-440. Actualmente se reconocen dos provincias biogeográficas en la plataforma marina argentina actual: la Magallánica y la Argentina. Las dos unidades difieren en su registro fósil. Se sugiere aquí que la evolución de las provincias fue compleja y caracterizada por migraciones, eventos de especiación, extinciones, pseudoextinciones. Durante el Mioceno ya había asociaciones de vertebrados marinos con similitudes taxonómicas con los de la Provincia Argentina pero no se detectaron hasta ahora asociaciones fósiles similares a las de la Magallánica hasta el Pleistoceno. Aquí describimos tres ricas asociaciones faunísticas marinas del Mioceno que se depositaron durante dos grandes transgresiones atlánticas: el 'Patagoniense' (Mioceno Temprano) y el 'Entrerriense' (Mioceno Medio a Tardío). La ausencia de asociaciones de tipo magallánicas en el Mioceno confirma la hipótesis de que la fauna templado-fría se distribuía más al sur en ese tiempo. En Patagonia, tal como en otras áreas, se registra un número mayor de formas actuales desde el Mioceno Temprano al Tardío. Los mamíferos acuáticos del Mioceno Tardío tenían un aspecto moderno; incluso alguna de las especies de peces perdura en la actualidad. Asimismo, en este trabajo llamamos la atención sobre la coexistencia de una diversidad muy alta de pingüinos con tiburones de ambientes templado-cálidos en la base de la Formación Gaiman. Interpretamos que estos pingüinos estaban habituados a soportar aguas más cálidas que los actuales. Finalmente, discutimos la pseudoextinción de vertebrados en el Océano Atlántico. [ABSTRACT FROM AUTHOR]

The Patagonian glaciations developed from the latest Miocene ( c. 6 Ma) in multiple events of varied duration and intensity. Most of the present glacial landscape is the result of the glacial modelling during the Pleistocene, since the Great Patagonian Glaciation (GPG; c. 1 Ma). The Patagonian Andes were covered by a continuous mountain ice sheet, from 37°S to Cape Horn (56°S), in at least five major glaciations over more than 15 cold events over the last million years. Before GPG, the glaciers were restricted to isolated ice caps along the mountain ranges. The present drainage network was developed after the Last Glacial Maximum [LGM; c. 25 calibrated kiloyears before present (cal. ka )], particularly those cases with drainage reversal, when the glaciers began to melt as a result of global climatic changes. The environmental impact of glaciations extended not only all over Patagonia, but to the Pampas as well. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, , 316-335. Las glaciaciones patagónicas se desarrollaron desde el final del Mioceno (ca. 6 Ma) en múltiples eventos, de variada duración e intensidad. La mayoría del paisaje andino actual es el resultado del modelado glaciario durante el Pleistoceno, desde la Gran Glaciación Patagónica (GGP; ca. 1 Ma). Los Andes Patagónicos fueron cubiertos por un manto de hielo de montaña continuo, desde 37°S hasta el Cabo de Hornos (56°S) a lo largo de por lo menos 5 glaciaciones mayores durante más de 15 eventos fríos en el último millón de años. Antes de la GGP, los glaciares estaban restringidos a casquetes glaciarios aislados a lo largo de las cadenas montañosas. El sistema de redes de drenaje actual, en especial en lo que hace a la inversión del drenaje, se desarrolló luego del Último Máximo Glacial (UMG; ca. 25 cal. ka A.P.), cuando los glaciares comenzaron a retirarse debido a cambios climáticos globales. El impacto ambiental de las glaciaciones se extendió, no sólo a toda la Patagonia, sino también a la región pampeana. [ABSTRACT FROM AUTHOR]

Late Miocene to Quaternary intraplate basaltic volcanism in the Al Ghab and Homs regions, northwestern Syria (the Al Ghab volcanic group and the Homs volcanic group), occurred roughly synchronously with the propagation of the Dead Sea Fault System in these regions. Petrographic evidence as well as major and trace element variations suggest that the basalts have undergone varying amounts of crystal fractionation of olivine ± clinopyroxene ± spinel, with feldspar fractionation only in the most evolved samples. The major and trace element chemistry and Nd–Sr–Pb isotopic variations of the basalts reflect both mantle source heterogeneity and relatively minor crustal contamination. Semi-quantitative assimilation–fractional crystallization modelling suggests that some samples may reflect assimilation of no more than 6% of upper continental crust, probably with Late Proterozoic Arabian Shield characteristics. Amongst the least crustally contaminated and relatively primitive samples, basanites are characterized by marked depletion of K, Rb and Zr relative to other neighbouring incompatible elements on primitive mantle normalized trace element diagrams. This, together with their low SiO2 and high TiO2 and Dy/Yb, is consistent with magma genesis involving a large proportion of garnet-bearing hornblendite or similar amphibole-rich metasomatic veins. Associated alkali and tholeiitic basalts with the higher SiO2, lower TiO2, less negative K, Rb and Zr anomalies, and moderately high Dy/Yb are consistent with melt extraction from a largely peridotitic mantle source. It is suggested that the compositional spectrum from basanite via alkali basalt to tholeiitic basalt can be explained by increasing degrees of metasomatic vein–wall-rock interaction, plus asthenospheric melt assimilation. In agreement with this is the identification of three distinct isotopic and chemical characteristics within the spectrum of mafic lavas, each of which can be referred to a unique mantle source (metasomatic vein, lithospheric wall-rock peridotite mantle and asthenospheric peridotite mantle). A decrease in eruption volume and increase in Si-undersaturation of the lavas from south (Homs) to north (Al Ghab) along the northern Dead Sea Fault System from latest Miocene to Quaternary times suggest a diminishing thermal perturbation and increasing importance of the amphibole-rich veins in magma genesis over time. It is proposed that the genesis of the oldest lavas reflects the arrival of asthenospheric melts beneath the Homs region, which with assimilation of lithospheric metasomatic veins and their wall-rocks produced the parental magmas of the Homs volcanic group. Subsequently, upwelling asthenospheric material could have been channelled northwards at the base of the lithosphere, presumably related to the northward propagation of the Dead Sea Fault System in the Pliocene. Cooling of this channelled asthenospheric material, which did not penetrate the lithosphere during this later period of magma genesis, provided the minimal thermal perturbation necessary for melting of amphibole-rich metasomatic veins and wall-rock peridotite within the lithosphere. [ABSTRACT FROM AUTHOR]

Material of Hispanomys (Rodentia, Cricetodontinae) is described from various localities at Batallones (MN10) (Madrid, Spain). All of it belongs to a single species, which differs from the other known species of the genus and a new taxon, , is created for it. The samples from the various localities show differences interpreted as being the result of slight age disparities amongst the different sites. Although they were previously thought to be coeval, Batallones 10 is probably older than Batallones 1, which is possibly older than Batallones 3. Hispanomys moralesi sp. nov. is characterized by several morphological features such as the lack of cingula and mesolophs, the presence of well-developed ectolophs, four- or five-rooted M1, short or absent mesolophids, and reduced and simplified M3. Hispanomys moralesi sp. nov. is a relatively derived species, the evolutionary stage of which is comparable to those of other members of the genus from the Upper Vallesian. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, , 725-747. [ABSTRACT FROM AUTHOR]

Uric acid (UA) is the end product of purine metabolism in humans due to the loss of uricase activity by various mutations of its gene during the Miocene epoch, which led to humans having higher UA levels than other mammals. Furthermore, 90% of UA filtered by the kidneys is reabsorbed, instead of being excreted. These facts suggest that evolution and physiology have not treated UA as a harmful waste product, but as something beneficial that has to be kept. This has led various researchers to think about the possible evolutionary advantages of the loss of uricase and the subsequent increase in UA levels. It has been argued that due to the powerful antioxidant activity of UA, the evolutionary benefit could be the increased life expectancy of hominids. For other authors, the loss of uricase and the increase in UA could be a mechanism to maintain blood pressure in times of very low salt ingestion. The oldest hypothesis associates the increase in UA with higher intelligence in humans. Finally, UA has protective effects against several neurodegenerative diseases, suggesting it could have interesting actions on neuronal development and function. These hypotheses are discussed from an evolutionary perspective and their clinical significance. UA has some obvious harmful effects, and some, not so well-known, beneficial effects as an antioxidant and neuroprotector. [ABSTRACT FROM PUBLISHER]

The gilgie ( Cherax quinquecarinatus) is among the more widespread of the six endemic south-western Australian freshwater crayfish species. In the present study, the phylogeographic structure of the gilgie was investigated across its distribution to determine whether patterns reflected those identified earlier in a co-distributed congeneric, the koonac ( Cherax preissii). Gilgies were sampled from 20 localities, a 412-bp fragment of the cytochrome c oxidase subunit I mitochondrial DNA gene was amplified from 75 individuals, and allozyme variation was assayed at nine loci. As in the koonac, three geographically-restricted lineages were identified: from the north-western, southern coastal, and intermediate/south-western regions. Phylogeographic breaks appeared to be congruent with those in the koonac. The extent of genetic differentiation among lineages was comparable to that in the koonac, suggesting temporal congruence of the historical events responsible for the observed structure. A relaxed Bayesian molecular clock suggested that the major clades and lineages in each species diverged in the Late Miocene–Early Pliocene (4.0–9.6 Myr ago), possibly resulting from increasing pulses of aridity. The retrieval of almost-identical phylogeographic structure in two co-distributed species suggests that biogeographic regions can be more accurately defined in south-western Australia. With the geographic fidelity of these lineages, the present data also provide evidence of the translocation of a single individual from the north-west to the south coast. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 385–402. [ABSTRACT FROM AUTHOR]

In their comment, Labails and Roest have raised several points against the kinematic model of Schettino and Turco for the central Atlantic region, which requires the existence of an independent Moroccan Plate during the Oligocene and the early Miocene. We thank these authors for giving us the opportunity to clarify some controversial points, but disagree with most of their objections and show that they are based either on a different interpretation of existing data or a distortion of the facts presented by Schettino and Turco. [ABSTRACT FROM AUTHOR]

We investigated the evolutionary history of a group of silky pocket mice (Heteromyidae: Perognathinae: Perognathus flavus species group) composed of the species P. flavus and P. merriami to determine patterns and postulate causes of geographical diversification across arid grasslands and intermontane basins in western North America. The region represents a topographically complex landscape with a Neogene history of dramatic geological and climatic transformations. Phylogenetic and dating analyses of mitochondrial DNA support an initial split among 4 major lineages during the late Miocene, and this hypothesis receives further support from analysis of a portion of the nuclear interphotoreceptor retinoid-binding protein (IRBP) gene. Two of these lineages have a restricted geographic distribution in the Chihuahuan Desert, and 2 have distributions ranging across large portions of the Chihuahuan Desert, Colorado Plateau, Great Plains, and Tamaulipan Plain. Within the 2 widespread lineages further geographical diversification likely was concentrated in the Pliocene, which coincided with the origin of several hypothesized geographic barriers. These results are consistent with models of allopatric divergence driven by pre-Pleistocene geological and climatic events, particularly the late-Miocene expansion of interior grasslands and Miocene-Pliocene evolution of Basin and Range geomorphology. Therefore, the biogeographic structure displayed in the flavus species group may be predictive for a range of sympatric taxa. [ABSTRACT FROM AUTHOR]

Bayesian methods are increasingly being used to estimate divergence times without the restrictive assumption of a global clock. Little is known about their reliability for shallow phylogenies where DNA sequence divergence is low. We analyzed both simulated and real sequences to evaluate dating methods in phylogenies with mid–late Miocene roots. A large number of data sets (5000) with 10 taxa each were simulated under a rate-drift model for trees with 2 topologies (balanced or unbalanced) and with different sets of divergence times (characterized by long or short external branches). Data were analyzed using Bayesian Markov chain Monte Carlo methods in which the prior on divergence times was specified from a birth–death process with species sampling (BDS) or a Dirichlet distribution using the programs MCMCTREE and MULTIDIVTIME. The programs generally performed well on shallow phylogenies, but posterior mean node ages were biased and 95% posterior intervals included true ages in fewer than 95% of trees in some analyses. This typically occurred when the 95% prior interval did not include the true age and/or sequence lengths were ≤ 1 kbp. Widths of posterior intervals were also very dependent on the position of the calibrated node within the tree, particularly when sequences were short. Different divergence times priors within MCMCTREE, MULTIDIVTIME, and BEAST were used to analyze mitochondrial DNA data sets from a Bovid subfamily (the Caprinae) from Asian Laudakia and North African Chalcides lizards. Posterior divergence times were quite sensitive to different BDS priors but less sensitive to different Dirichlet priors. Our study demonstrates the impact of the prior on divergence times in shallow phylogenies and shows that 1) prior intervals on nodes should be assessed as a prerequisite to a dating analysis, 2) ≥ 1 kbp of quite rapidly evolving sequence may be required to obtain accurate posterior means and usefully narrow posterior intervals. [ABSTRACT FROM PUBLISHER]

One of the classic examples of faunal turnover in the fossil record is the Miocene transition from faunas dominated by anchitheriine horses with low-crowned molar teeth to faunas with hipparionine horses characterized by high-crowned teeth. The spread of hipparionine horses is associated with increased seasonality and the expansion of open habitats. It is generally accepted that anchitheriine horses did not display an evolutionary increase in tooth crown height prior to their extinction. Nevertheless, to test whether anchitheriines showed any changes interpretable as adaptation to local conditions, we analyzed molar teeth from multiple populations of Anchitherium in three dimensions. Our results show differences in tooth morphology that suggest incipient hypsodonty in Spain, the first region experiencing increasingly arid conditions in the early Miocene of Europe. Furthermore, analyses of tooth wear show that Spanish specimens cluster with present ungulates that eat foliage together with grasses and shrubs, whereas German specimens cluster with present-day ungulates that eat mostly foliage. Taken together, even a taxon such as Anchitherium, with a long and successful history of forest adaptation, did respond to regional environmental changes in an adaptive manner. [ABSTRACT FROM AUTHOR]

New palaeomagnetic data from the central and western sectors of the Trans-Mexican volcanic belt (TMVB) are presented and analysed for palaeosecular variation (PSV) and tectonic rotations. Fifty-one sites with geochronological control were collected from selected volcanic lava flows, which cover the temporal and spatial activity in the magmatic arc for the past ∼11 Ma. Rock magnetic experiments reveal that generally Ti-poor titanomagnetites, sometimes maghemitized, are the magnetic carriers of the characteristic remanent magnetizations. After analysis of detailed progressive demagnetization data, 47 mean-site directions are determined. In addition, data from previous regional palaeomagnetic study in the eastern TMVB sector (53 sites) are re-analysed. Palaeomagnetic data are grouped according to geographic distribution (three structural sectors) and according to age (late Miocene, Pliocene or Quaternary). To avoid discarding tectonic effects, the less stringent criterion (i.e. a fixed cut-off angle to the mean equal to 45°) was applied to identify transitional data, affecting four sites. Palaeomagnetic results, backed by positive reversal tests, indicate no palaeomagnetically detectable vertical-axis block rotations in the study areas. The nearly geocentric axial dipole (GAD) inclinations suggest no significant tilting effects and negligible quadrupolar contributions. Since the mean palaeomagnetic directions for the study areas do not differ from reference directions from the North American polar wander path, two data sets for 11–5 and 5–0 Ma are tested for geomagnetic purposes. Virtual geomagnetic poles (VGPs) were selected using both fixed −45°- and optimum, variable cut-off angles. This resulted in VGP dispersions that increase back on time and are consistent with those obtained from globally distributed observations at the site latitude for their respective age ranges and cut-off criteria. Palaeomagnetic data from late Miocene and Pliocene TMVB rocks can be considered in the databases for time averaged field (TAF) and palaeosecular variation from lavas (PSVL) analyses and geomagnetic field geometry characterization during the past ∼11 Ma. [ABSTRACT FROM AUTHOR]

A new genus of Gliridae, Simplomys gen. nov. is proposed. It contains glirids with a simplified dental pattern from the European Early and Middle Miocene. Simplomys gen. nov. includes several species originally described as Pseudodryomys such as Simplomys simplicidens, Simplomys robustus, Simplomys julii, and Simplomys aljaphi. In addition, a new species, Simplomys meulenorum sp. nov., is proposed from the Spanish Miocene. The species of this genus share not only a very reduced and simplified dental morphology, but also unique dental proportions that clearly separate them from any other genera of Gliridae. Simplomys gen. nov. is recorded in most of the fossil faunas from the Early and Middle Miocene of the Iberian Peninsula, and shows the maximum diversity in this area during Mammal Neogene Zones MN 3 and MN 4. The genus has been also recorded in other European countries such as France, Germany, and Switzerland, conferring to this very characteristic taxon an important role for biochronological correlations within the European continent. [ABSTRACT FROM AUTHOR]

Geological and climatic processes potentially alter speciation rates by generating and modifying barriers to dispersal. In Southeast Asia, two processes have substantially altered the distribution of land. Volcanic uplift produced many new islands during the Miocene–Pliocene and repeated sea level fluctuations during the Pleistocene resulted in intermittent land connections among islands. Each process represents a potential driver of diversification. We use a phylogenetic analysis of a group of Southeast Asian shrews ( Crocidura) to examine geographic and temporal processes of diversification. In general, diversification has taken place in allopatry following the colonization of new areas. Sulawesi provides an exception, where we cannot reject within-island speciation for a clade of eight sympatric and syntopic species. We find only weak support for temporally declining diversification rates, implying that neither volcanic uplift nor sea level fluctuations had a strong effect on diversification rates. We suggest that dynamic archipelagos continually offer new opportunities for allopatric diversification, thereby sustaining high speciation rates over long periods of time, or Southeast Asian shrews represent an immature radiation on a density-dependent trajectory that has yet to fill geographic and ecological space. [ABSTRACT FROM AUTHOR]

We investigate the seismic attenuation along a 160 km profile from the Lower to the High Himalaya in the Garhwal region, India, through the analysis of Lg waveforms from regional earthquakes recorded on 18 broadband seismographs with interstation spacing of 7–10 km. Lateral variability in attenuation is derived through the inversion of 36 two-station measurements using a global optimization scheme. We observe a contrasting attenuation property in the two Himalayan belts: the Lower Himalaya has of 742 ± 235 similar to those observed in the Indian shield, whereas the High Himalaya is characterized by an unusually low value of 30–60. The seismic attenuation is also well correlated with the P-wave teleseismic traveltime residual pattern: faster arrival (approximately 0.2 s) at stations in the Lower Himalaya as compared to azimuthally independent time delay of ∼0.75 s for the High Himalayan stations. The high attenuation and low velocity in the High Himalaya suggests that low viscosity and partial melt in the crust can be correlated to the presence of Miocene leucogranite plutons in this Himalayan belt, a magmatic product of the Indo-Asian collision and presumably evidence of a partial melting event. This shallow low viscosity channel possibly connects the mid-crustal channel beneath Tibet. [ABSTRACT FROM AUTHOR]

Around 4370 km of new seismic reflection data, collected along the East Greenland margin between 71°30′N and 77°N in 2003, provide a first detailed view of the sediment distribution and tectonic features along the East Greenland margin. After processing and converting the data to depth, we correlated ODP-Site 913 stratigraphy into the new seismic network. Unit GB-2 shows the greatest glacial sediment deposits beneath the East Greenland continental shelf. This unit is characterized by the beginning of prograding sequences and has, according to our stratigraphic correlation, a Middle Miocene age. It might have been caused by rapid changes in sea level and/or glacial erosion by an early ice sheet or glaciers along the coast. A basement high, presumably a 360 km long basement structure at 77°N–74°54′N, prevents continuous sediment transport from the shelf into the deep sea area in times before 15 Myr. The origin of this prominent structure remains speculative since no rock sample from this structure is available. Seaward dipping reflectors at the eastern flank of this structure strongly support that it is a volcanic construction and is most likely emplaced on continental or transitional crust. The compilation of sediment thickness provide an insight into the regional sediment distribution in the Greenland Basin. An average sediment thickness of 1 km is observed. The north bordering Boreas Basin has a sediment thickness of 1.8 km close to the Greenland fracture zone (GFZ). [ABSTRACT FROM AUTHOR]

Analyses of molecular phylogenies of three unrelated tropical marine gastropod genera, Turbo, Echinolittorina, and Conus, reveal an increase in the rate of cladogenesis of some Indo-West Pacific (IWP) clades beginning in the Late Oligocene or Early Miocene between 23.7 and 21.0 million years ago. In all three genera, clades with an increased rate of diversification reach a maximum of diversity, in terms of species richness, in the central IWP. Congruence in both the geographical location and the narrow interval of timing suggests a common cause. The collision of the Australia and New Guinea plate with the southeast extremity of the Eurasian plate approximately 25 Mya resulted in geological changes to the central IWP, including an increase in shallow-water areas and length of coastline, and the creation of a mosaic of distinct habitats. This was followed by a period of rapid diversification of zooxanthellate corals between 20 and 25 Mya. The findings reported here provide the first molecular evidence from multiple groups that part of the present-day diversity of shallow-water gastropods in the IWP arose from a rapid pulse of speciation when new habitats became available in the Late Oligocene to Early Miocene. After the new habitats were filled, the rate of speciation likely decreased and this combined with high levels of extinction (in some groups), resulted in a slow down in the rate of diversification in the genera examined. [ABSTRACT FROM AUTHOR]

The Miocene basaltic–andesitic lavas and Cretaceous granites were sampled in the Abukuma Terrane of northeast Honshu for geochronological and palaeomagnetic investigations to determine precise timing of counter-clockwise rotation of NE Japan. Characteristic component with unblocking temperature of 560–590 °C is isolated from 26 sites of the Takadate and Ryozen Formations and 12 sites of the Cretaceous granites. Concordant northwesterly palaeomagnetic directions ( D= 265°–331°) are observed in the Cretaceous granites of the Abukuma Terrane. The Cretaceous mean-palaeomagnetic direction from this terrane ( D= 313.5°, I= 54.6°, α95= 6.3° and N= 20) is almost identical to Oligo-Miocene (33–20 Ma) palaeomagnetic direction reported from the Japan Sea side of NE Japan as well as to the Cretaceous palaeomagnetic direction reported from the Kitakami Terrane. This type of behaviour clearly suggests that the Abukuma Terrane underwent a coherent counter-clockwise rotation as a part of NE Japan after 20 Ma. Conventional potassium (K)-Argon (Ar) dating method performed on the plagioclase grains revealed distinctive ages of 14.44 ± 0.88 and 16.52 ± 0.82 Ma for the Takadate Formation (11 sites) and the Ryozen Formation (eight sites), respectively. This type of behaviour indicates that two independent episodes of volcanic activities were probably responsible for the production of igneous rocks in the Takadate and Ryozen areas. Northerly declination is obtained from the Takadate Formation ( D= 355.3°, I= 39.4°, α95= 11.6°), while slightly westerly deflected declination appears in the Ryozen Formation ( D= 333.5°, I= 58.0° and α95= 9.6°). The here presented results, therefore, suggest that the province of NE Japan was still experiencing a counter-clockwise rotation at 16.5 Ma, however by 14.4 Ma the rotational motion has completely ceased. Compared with the available palaeomagnetic and geochronological data from SW Japan, rotational motion in both provinces of NE and SE Japan has already been ceased by 14 Ma. Thus any additional evidence regarding the complete cessation of rotational motions in NE Japan will provide a key to understand the timing of opening in the Japan Sea. [ABSTRACT FROM AUTHOR]

Historical changes in the distributions of temperate species in response to Milankovitch climate cycles have been well documented in palaeontological studies and recently evaluated with phylogeographical methods. How these cycles influence biological diversity remains a matter of debate. Molecular surveys of terrestrial and freshwater fauna demonstrate glacial refugia in low latitudes and range expansions into high latitudes, but few genetic studies have assessed the corresponding impact on marine fauna. In the present study, mtDNA sequences ( N = 84) are surveyed to understand the impact of long-term climate oscillations on ‘Old World’ anchovies (genus Engraulis), a monophyletic group occurring in north and south temperate zones of the eastern Atlantic and the western Pacific. The analysis of a 521-bp sequence of mtDNA cytochrome b indicates a late Miocene or Pliocene dispersal from the north-eastern Pacific (California–Mexico) to the north-western Pacific (Japan), followed by Pleistocene dispersal from the north-western Pacific to Europe. Geography mandates that populations in southern Africa and Australia were stepping-stones for this dispersal. However, neither population occupies an intermediate position in the mtDNA genealogy; both populations are more recently derived from their northern neighbours. Haplotype diversity is high ( h = 0.93–0.97) in European, Australian, and Japanese anchovies, but low ( h = 0.22) in the southern African population, where all haplotypes are more closely related to European specimens than to each other. These southern populations occupy a precarious position, lacking north–south coastlines that allow range shifts during climatic extremes. Recurring extinctions and episodic recolonizations from northern hemisphere populations are the likely results. In this case, ocean-climatic changes retard rather than enhance opportunities for evolutionary radiations. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 673–689. [ABSTRACT FROM AUTHOR]

Non-linear teleseismic bodywave tomography with data of the 1999 CALIXTO field experiment (Carpathian Arc Lithosphere X-Tomography) in Romania provides high-resolution imaging of the upper-mantle structure. In this paper, we present the relative P-wave velocity distribution of the lithosphere/asthenosphere system. Smearing from strong crustal velocity anomalies into the upper mantle is successfully suppressed by traveltime corrections with an a priori 3-D regional crustal velocity model (see Martin et al. 2005 , herein referenced as paper 1). Our high-resolution image shows a high-velocity body beneath Vrancea and the Moesian platform with a NE–SW orientation between 70 and 200 km depth. Beneath 200 km a change in the orientation from NE–SW to N–S can be observed. The body reaches a maximum depth of about 350–370 km. The velocity perturbation is maximal between 110 and 150 km depth (5.2–5.8 per cent) and almost constant for depths beneath 200 km (3.2–3.8 per cent). As most authors of previous studies agree on Miocene subduction along the arc followed by soft continental collision we interpret the high-velocity body as the subducted, yet not fully detached slab. The NE-part of the slab appears to be mechanically coupled to the Moesian lithosphere and hosts the intermediate depth seismicity. In contrast the aseismic SW-part is interpreted as decoupled from the overlying lithosphere and torn off from the underlying lithospheric material beneath 200 km depth. Low velocity anomalies NW of the slab above 110 km depth are interpreted as a shallow asthenospheric upwelling. Further low-velocity anomalies are in agreement with a lithosphere-asthenosphere boundary at 110–150 km depth below the Moesian platform and deeper than 200 km under the East European platform (EEP). The tomographic images support models proposing slab rollback during subduction/collision, followed by slab steepening and lithospheric delamination. The different degrees of mechanical coupling of the slab to the overlying lithosphere allow to understand the loci of seismicity as volumes of stress concentration. Independent on the specifics of data interpretation our high-resolution image is a novel contribution to understand the process of ongoing lithospheric detachment associated with strong intermediate-depth seismicity in SE-Romania. [ABSTRACT FROM AUTHOR]

Polypterus faraou sp. nov. (Cladistia, Polypteridae) from the Late Miocene of Toros-Menalla (western Djourab, Chad) is described on the basis of a subcomplete articulated skeleton preserved in three dimensions. This is the first time such a complete fossil polypterid skeleton has been described. It is the only verifiable fossil record for the genus Polypterus. P. faraou closely resembles P. bichir and P. endlicheri, extant fish found in the Chad–Chari system. Intrarelationships among the polypterids are not yet resolved: however, P. faraou shows a primitive shape of the body and a primitive shape of the opening of the lateral line on the scales, similar to that of three living species ( P. bichir, P. endlicheri and P. ansorgii). © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society, 2006, 146, 227–237. [ABSTRACT FROM AUTHOR]

A large number of plant macrofossils from several Middle to Upper Miocene localities from Iceland have been studied. The fossil material includes four ferns and fern allies, seven conifers, and about 40 species of flowering plants. Betula islandica and Salix gruberi are described as new species. Coniferous twigs previously ascribed to the genus Sequoia are shown to belong to Cryptomeria based on macro-morphological and epidermal features. Fossil plants from Iceland are compared with coeval fossil taxa from Europe and North America and with living plants. The main finding is that the Miocene flora of Iceland belongs to a widespread Neogene northern hemispheric floral type including plants whose representatives are restricted to East Asia, North America and to western Eurasia at the present time. Previously inferred conspicuous similarities to North American modern equivalents appear to be misleading. The type of vegetation in four plant-bearing sedimentary formations from the late Mid Miocene to Late Miocene, the 12 Ma Brjánslækur-Seljá Formation, the 10 Ma Tröllatunga-Gautshamar Formation, the 9–8 Ma Skarðsströnd-Mókollsdalur Formation, and the 7–6 Ma Hreðavatn-Stafholt Formation, corresponds to a humid temperate broadleaved (deciduous)–coniferous mixed forest dominated by Betulaceae, Fagaceae and Acer. Changes in species composition in the sedimentary formations reflect a shift from warm temperate (Cfa climate) to cool temperate (Cfb climate) conditions from the late Mid Miocene to the latest Miocene. This shift was connected to repeated phases of extinction and colonization. Specifically, one set of thermophilic taxa including Magnolia, Liriodendron, Sassafras and Comptonia went extinct between 12 and 10 Ma, and appears to have been replaced by another set of thermophilic taxa in the 10 Ma formation (Juglandaceae aff. Pterocarya/Cyclocarya, Rhododendron ponticum type). The 9–8 and 7–6 Ma formations are characterized by taxa that migrated to Iceland from Europe, such as Fagus gussonii, Betula cristata and Pterocarya fraxinifolia type. Although there is convincing evidence that plants colonized Iceland both from North America and Europe until 12 Ma, migration in the younger formations (9–8, 7–6 Ma) is suggested to have occurred mainly from Europe. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 149, 369–417. [ABSTRACT FROM AUTHOR]

Studies of natural and sexual selection in wild populations of Drosophila have historically provided strong inference for the maintenance of inversion polymorphism. Analysis of geographical variation in the Drosophila robusta chromosomal data collected over more than 50 years from 133 natural populations across eastern North America has confirmed several north–south and east–west clines in the frequencies of some gene arrangements and linked arrangement combinations. Patterns of geographical variation, including several north–south clines, revealed by regression and spatial autocorrelation analyses are concordant with palaeoclimatic shifts, Pleistocene glaciations and historical changes in the composition of North American forest communities. Because D. robusta is a sap-breeder, using the microbe-infested sap exudates of a number of deciduous tree species in which they carry out their life cycle, shifts in climate and palaeovegetation types since the formation of the eastern deciduous forests in the Miocene are hypothesized to be major factors influencing patterns of inversion polymorphisms across the range of this drosophilid species. In areas where sharp deviations in frequencies have been observed, particularly in the mid-western and western portions of the range, these divisions parallel historical geographical disjunctions in the species range that have yet to promote divergence and species formation despite the long history of D. robusta in North America. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 81, 395–411. [ABSTRACT FROM AUTHOR]

An Upper Miocene magnetic polarity stratigraphy has been developed for the C3r to C5ABn interval of ODP site 1092 from the sub-Antarctic South Atlantic ( ). New data from X-ray fluorescence (XRF) scanning of half cores has led to development of a revised composite depth section for the site. This has implications for the magnetostratigraphic interpretation. Using the shipboard-derived composite section, four subchrons were identified within the normal polarity zone correlative to C5n.2n. The revised composite section results in subchrons C5n.2n-2 and C5n.2n-3 of becoming a single subchron recorded in two overlapping cores. The revised number of polarity subchrons within C5n.2n is now three, rather than four, which is consistent with the number of ‘cryptochrons’ recognized in marine oceanic anomaly data. [ABSTRACT FROM AUTHOR]

A new barbourofelid species, Prosansanosmilus eggeri , is described from the Middle Miocene (MN 5) locality of Sandelzhausen, Germany. It differs from all other European barbourofelid species in being smaller and showing a more plesiomorphic morphology, especially in the relatively less developed sabretooth adaptations, low accessory cusps on the premolars, and the remnant of a very small talonid on the carnassial. The species is, however, stratigraphically later than the more apomorphic P. peregrinus, which is known from MN 4 of Germany and France. A phylogenetic analysis based on dental characters of early nimravids, barbourofelids and felids supports previous results on skull morphology of Barbourofelis that Barbourofelinae is not closely related to the Late Eocene and Oligocene Nimravinae. Instead, both subfamilies should be treated as separate families, with the Barbourofelidae closely related to the Felidae. The Barbourofelidae differ from the Felidae as well as from the Nimravidae s.s., particularly in the unique morphology of their basicranium. They presumably originated in Africa; P. eggeri sp. nov. is interpreted as part of a Miocene immigration of African faunal elements into Europe that took place at the beginning of MN 5. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 140, 43−61. [ABSTRACT FROM AUTHOR]

Carnivores are ecologically diverse mammals. Dietary adaptations vary from strict herbivory to pure carnivory. These adaptations have evolved independently several times within families, so evolution within the order is iterative. I used 2 databases to examine whether ecological adaptations have an effect on longevity or spatial distributions of fossil carnivores. Miocene hypercarnivorous species had, on average, the widest spatial distributions. Their temporal distributions were not significantly longer than those of other carnivores. Body size also had a significant interaction with maximum spatial distribution. Largebodied carnivores, regardless of feeding adaptations, had larger geographical ranges, but did not have greater longevity. However, when all the data were pooled, temporal distribution had a significant correlation with spatial distribution. The position of hypercarnivores at the top of the food chain and their specialized adaptations for meat eating probably increased their extinction risk to the same level of more narrowly distributed, less specialized carnivores. [ABSTRACT FROM AUTHOR]

Studies upper Miocene magnetic stratigraphy using samples from an Ocean Drilling Program site in sub-Antarctic South Atlantic Ocean. Upper Miocene polarity stratigraphies; Polarity subchrons.

We report high-precision multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) analyses of Hf isotopic compositions for 39 Kerguelen Archipelago volcanic rocks that add a new perspective to the temporal evolution of the Kerguelen mantle plume. Samples cover the entire range of chemical and Sr, Nd and Pb isotopic variations reported for the archipelago, and vary in age from 29 to 0·1 Ma. Their Hf isotopic compositions show the largest variation for an individual oceanic island and εHf correlates negatively with alkalinity. The Hf–Nd isotopic compositions of the pre-Miocene flood basalt group (>25 Ma) are distinct from those of the <10 Ma group of Upper Miocene and Quaternary Mt. Ross volcanic rocks and plot along separate en-echelon εHf–εNd arrays. The Lower Miocene Series mildly alkaline basalts from the Southeast Province are transitional between the two groups and indicate a major replacement of plume source components over a relatively short period of time. The geochemical systematics of the >25 Ma group of flood basalts require interaction between a shallow reservoir of asthenospheric mantle or oceanic lithosphere and the Kerguelen plume core, best represented by the Mt. Crozier basalts on the archipelago. This scenario is consistent with the relative proximity of the Kerguelen Archipelago to the Southeast Indian Ridge (∼300–400 km) when the >25 Ma flood basalts erupted. The younger alkaline volcanic rocks were generated by low-degree melting in the plume envelope, an area of enriched mantle material, different from the plume core, and presumably formed by different combinations of old recycled oceanic crust and plateaux. The enriched geochemical character of the Kerguelen plume core supports the hypothesis that the EM I-type plume source includes recycled oceanic plateaux. [ABSTRACT FROM PUBLISHER]

Presents absolute palaeointensity results from the Trans-Mexican Volcanic Belt and discusses their implications for the late Miocene geomagnetic field strength. Selection of samples from a collection of Central Mexico Miocene volcanic units sampled for magnetostratigraph; Palaeointensity estimates resulting from the Thellier palaeointensity experiments.

Examines the palaeomagnetism of the Miocene Farellones volcanic formation. Optical observations of opaque minerals; Chemical alteration of the magnetic minerals during hydrothermalism; Relationship between natural remanent magnetization and thermal remanent magnetization.

In south Karakorum, the western prolongation of southern Tibet, three distinct types of magmatic rocks were emplaced during the Neogene: (1) 22–24 Myr old lamprophyres, characterized by strong enrichment in large ion lithophile (LILE) and light rare earth elements (LREE), 87Sr/86Sr(i) = 0·7096, εNd(i) = –7, and εHf = –9, interpreted to reflect partial melting of a previously metasomatized spinel-lherzolite mantle source; (2) the 21–26 Myr old Baltoro high Ba–Sr granitoids, likewise strongly enriched in LILE and LREE, with 87Sr/86Sr(i) = 0·7034–0·7183, εNd(i) = –6·5 to –11·0, and εHf = –1·8 to –8·0, produced by partial melting of amphibole-bearing rocks in the lower crust, possibly the root of south Karakorum Cretaceous magmatic arc; (3) the 8–9 Myr old Hemasil syenite and its associated lamprophyre, also both enriched in incompatible elements but with isotopic compositions closer to those of depleted mantle (87Sr/86Sr(i) = 0·7043–0·7055, εNd(i) = ·5 – 4·3, and εHf = 10·4 – 11·2). The Hemasil syenite is interpreted as the product of partial melting of a time-integrated depleted spinel-lherzolite source that was enriched in K and LREE during a recent metasomatic event. We propose that the lamprophyres were formed during partial melting of the South Asian mantle previously metasomatized by fluids derived from the subducted Indian continental crust. This melting episode is interpreted to be related to a break-off event that occurred within the subducting Indian continental lithosphere. Intrusion of the resulting lamprophyric melts into the previously thickened south Karakorum crust caused partial melting of calc-alkaline igneous protoliths and generation of the Baltoro granitoids. Late-stage syenitic magmas were produced by low-degree partial melting during upwelling and adiabatic decompression of depleted mantle along the Shigar strike-slip fault. [ABSTRACT FROM AUTHOR]