Small mammal (rodents and lagomorphs) European biogeography from the Late Oligocene to the mid Pliocene

Aim To analyse the fossil species assemblages of rodents and lagomorphs from the European Neogene in order to assess what factors control small mammal biogeography at a deep‐time evolutionary time‐scale. Location Western Europe: 626 fossil‐bearing localities located within 31 regions and distributed among 18 successive biochronological units ranging from c. 27 Ma (million years ago; Late Oligocene) to c. 3 Ma (mid Pliocene). Methods Taxonomically homogenized pooled regional assemblages are compared using the Raup and Crick index of faunal similarity; then, the inferred similarity matrices are visualized as neighbour‐joining trees and by projecting the statistically significant interregional similarities and dissimilarities onto palaeogeographical maps. The inferred biogeographical patterns are analysed and discussed in the light of known palaeogeographical and palaeoclimatic events. Results Successive time intervals with distinct biogeographical contexts are identified. Prior to c. 18 Ma (Late Oligocene and Early Miocene), a relative faunal homogeneity (high interregional connectivity) is observed all over Europe, a time when major geographical barriers and a weak climatic gradient are known. Then, from the beginning of the Middle Miocene onwards, the biogeography is marked by a significant decrease in interregional faunal affinities which matches a drastic global climatic degradation and leads, in the Late Miocene (c. 11 Ma), to a marked latitudinal pattern of small mammal distribution. In spite of a short rehomogenization around the Miocene/Pliocene boundary (6–4 Ma), the biogeography of small mammals in the mid Pliocene (c. 3 Ma) finally closely reflects the extant situation. Main conclusions The resulting biogeographical evolutionary scheme indicates that the extant endemic situation has deep historical roots corresponding to global tectonic and climatic events acting as primary drivers of long‐term changes. The correlation of biogeographical events with climatic changes emphasizes the prevalent role of the climate over geography in generating heterogeneous biogeographical patterns at the continental scale.     

Middle Eocene–Early Pliocene Subantarctic planktic foraminiferal biostratigraphy of Site 1090, Agulhas Ridge

The analysis of planktic foraminiferal assemblages from Site 1090 (ODP Leg 177), located in the central part of the Subantarctic Zone south of South Africa, provided a geochronology of a 330-m-thick sequence spanning the Middle Eocene to Early Pliocene. A sequence of discrete bioevents enables the calibration of the Antarctic Paleogene (AP) Zonation with lower latitude biozonal schemes for the Middle–Late Eocene interval. In spite of the poor recovery of planktic foraminiferal assemblages, a correlation with the lower latitude standard planktic foraminiferal zonations has been attempted for the whole surveyed interval. Identified bioevents have been tentatively calibrated to the geomagnetic polarity time scale following the biochronology of Berggren et al. (1995). Besides planktic foraminiferal bioevents, the disappearance of the benthic foraminifera Nuttallides truempyi has been used to approximate the Middle/Late Eocene boundary. A hiatus of at least 11.7 Myr occurs between 78 and 71 m composite depth extending from the Early Miocene to the latest Miocene–Early Pliocene. Middle Eocene assemblages exhibit a temperate affinity, while the loss of several planktic foraminiferal species by late Middle to early Late Eocene time reflects cooling. During the Late Eocene–Oligocene intense dissolution caused impoverishment of planktic foraminiferal assemblages possibly following the emplacement of cold, corrosive bottom waters. Two warming peaks are, however, observed: the late Middle Eocene is marked by the invasion of the warmer water Acarinina spinuloinflata and Hantkenina alabamensis at 40.5 Ma, while the middle Late Eocene experienced the immigration of some globigerinathekids including Globigerinatheka luterbacheri and Globigerinatheka cf. semiinvoluta at 34.3 Ma. A more continuous record is observed for the Early Miocene and the Late Miocene–Early Pliocene where planktic foraminiferal assemblages show a distinct affinity with southern mid- to high-latitude faunas.     

Palynology of OGS-6a and OGS-7, two new 2.6 Ma archaeological sites from Gona, Afar, Ethiopia: Insights on aspects of Late Pliocene habitats and the beginnings of stone-tool use

Fossil pollen grains extracted from sediments sampled from OGS-6a and OGS-7, two newly excavated Late Pliocene sites of Gona, in the Afar Depression of Ethiopia, indicate a high percentage of afromontane forest and highland taxa (36.8-43.3%), among which Podocarpus cf. gracilor is dominant (19.6-24.2%). Forest taxa typical of the afromontane phytogeographic region have also been identified in the samples. The overall pollen spectrum suggests a mosaic of open and closed habitats, with a considerable wooded environment present during the time associated with the beginnings of early hominid use of flaked stones at Gona. Here we provide details of the results from the pollen analyses. The two sites lie 4-8 m directly below a volcanic tuff dated by ⁴⁰Ar/³⁹Ar to 2.53 ± 0.15 million years (Ma). The materials were recovered within fine-grained sediments located just above a geomagnetic polarity transition identified as the Gauss-Matuyama boundary dated close to 2.6 Ma, also corroborating the earlier age reported for the East Gona artifacts from EG-10 and EG-12. Thus, the stone artifacts, fossilized broken fauna and pollen grains from OGS-6a and OGS-7 represent archaeological materials from the world's oldest securely dated sites, and offer insights on aspects of the palaeoenvironments around the time of the beginnings of ancestral hominid use of flaked stones, ca. 2.6 Ma.     

Ecological change in the lower Omo Valley around 2.8 Ma

Late Pliocene climate changes have long been implicated in environmental changes and mammalian evolution in Africa, but high-resolution examinations of the fossil and climatic records have been hampered by poor sampling. By using fossils from the well-dated Shungura Formation (lower Omo Valley, northern Turkana Basin, southern Ethiopia), we investigate palaeodietary changes in one bovid and in one suid lineage from 3 to 2 Ma using stable isotope analysis of tooth enamel. Results show unexpectedly large increases in C₄ dietary intake around 2.8 Ma in both the bovid and suid, and possibly in a previously reported hippopotamid species. Enamel δ¹³C values after 2.8 Ma in the bovid (Tragelaphus nakuae) are higher than recorded for any living tragelaphin, and are not expected given its conservative dental morphology. A shift towards increased C₄ feeding at 2.8 Ma in the suid (Kolpochoerus limnetes) appears similarly decoupled from a well-documented record of dental evolution indicating gradual and progressive dietary change. The fact that two, perhaps three, disparate Pliocene herbivore lineages exhibit similar, and contemporaneous changes in dietary behaviour suggests a common environmental driver. Local and regional pollen, palaeosol and faunal records indicate increased aridity but no corresponding large and rapid expansion of grasslands in the Turkana Basin at 2.8 Ma. Our results provide new evidence supporting ecological change in the eastern African record around 2.8 Ma, but raise questions about the resolution at which different ecological proxies may be comparable, the correlation of vegetation and faunal change, and the interpretation of low δ¹³C values in the African Pliocene.     

Palynology: A useful tool in understanding palaeoclimatic changes through the Pliocene-Pleistocene from the deep offshore Niger Delta,Nigeria

Recent global ecological problems have necessitated more research into past environments so that accurate comparisons between past and present climatic conditions can be established and projections made for the future. In order to achieve this, palynological data from Well-C from the deep offshore (> 200 m) Niger Delta region were employed in an attempt to reconstruct the Late Pliocene-Pleistocene palaeoclimate. Four informal palynofloral assemblage zones (PAZ) I–IV are defined and correlated with four major cycles of alternating dry and wet climatic conditions. Within the major cycles, savanna and montane pollen assemblages became dominant in the late-Pliocene and mid-Pleistocene, while mangroves, brackishwater swamp, freshwater swamp and lowland rainforest prevailed during the early- and late-Pleistocene. The palaeoclimate of the late Pliocene and mid-Pleistocene was relatively colder and drier, with alternating relatively warmer and wetter conditions in the early and late Pleistocene, respectively. The pollen data from Well-C showed periods of climatic change during Late Pliocene-Pleistocene times, while the periods of climatic change revealed by pollen data from Lake Tilla, NE Nigeria, during Holocene times ranged from ∼2.0 to ∼3.8 Ka. Therefore, the cyclicity of climate change during Upper Pliocene-Pleistocene time is far greater than that of Holocene times. Our palaeo-climatic reconstruction conflicts with those that indicate predominantly dry climatic conditions in the Niger Delta region during the Pliocene-Pleistocene. The reconstructed palaeoclimate in this study can help to compare the past climatic conditions to that of the present and perhaps serve as a basis for studies of future climatic change.     

Cathaya (Pinaceae) pollen from Mio-Pliocene sediments in the Himi area,central Japan

This paper describes the pollen morphology of Cathaya from well-dated Mio-Pliocene sediments in the Himi area of Toyama Prefecture in central Japan. The geological distribution of the genus shows that it was present around the study area and in northern Japan from at least the Middle Miocene to the Early Pleistocene. The genus flourished in the Early Pliocene when the climate was warm, and became extinct in Japan in or after the Early Pleistocene because of climatic deterioration.     

Paleovegetation and paleoclimate in middle-late Pliocene, Shanxi, central China

Sequences of lacustrine sediments developed in intermontane basins in the middle-eastern Shanxi Plateau of China have been investigated in order to reconstruct the paleovegetation and paleoclimate for the middle-late Pliocene. According to the magnetostratigraphy and the fossil assemblages, the lacustrine sediments of Yushe and Taigu Basins were deposited between 5.5 and 2.5 Ma BP. The Zhangcun and Xiaobai Formations are considered to cover a similar period, ranging from 3.5 to 2.5 Ma BP. An increase of Picea and Abies shows that the climate began to become cold after about 4.4 Ma BP. A cold-wet episode, with relatively warm-dry and warm-humid intervals, occurred between 3.6 and 2.5 Ma BP in the Yushe and Taigu Basins. An increase Artemisia, Chenopodiaceae and Ephedra shows that the climate became drier after 2.5 Ma BP. The climate changes of this period probably reflect variations of the East Asian winter and summer monsoons, with an increase winter monsoon activity during the early Pleistocene.     

The Zanclean palaeofloras around the Mont-Dore strato-volcano: A window into upper Neogene vegetation and environments in the Massif Central (Puy de Dome,France)

New Pliocene macrofloras and microfloras perfectly preserved from the Mont-Dore (Puy-de-Dôme, Massif central, France) have been reinvestigated. Samples come from different stratigraphical levels collected from three localities, Lac Chambon, La Gratade and Pont de Chocol. The ⁴⁰Ar/³⁹Ar radiometric datings bracketing the Chambon Lake and La Gratade fossil-bearing horizons give 4.46 ± 0.05 Ma and 3.94 ± 0.04 Ma, respectively, representative of the Zanclean Stage (= Brunssumian B and C), a period of the early Pliocene (5.32 to 3.6 Ma), much older than previously thought (i.e., Piacenzian). Pont de Chocol is considered to be close biostratigraphically, or even identical in age to La Gratade. Detailed morphological evaluation of leaf morphotypes completed with pollen analysis contributed to the better taxonomic knowledge of these palaeofloras. The overview focuses on floristic and phytostratigraphical characteristics of the defined stratigraphical units and their dating and correlation with previously defined palaeofloristic units of the Massif central. The study provides detailed identifications of plants representing 11 gymnosperms among which Pinaceae (pollen and winged seeds), Cupressaceae including “Taxodioid” pollen grains and Sciadopitaceae families (only pollen). Besides, different angiosperm trees and shrubs have been determined from both micro- and macro-remains. Fagaceae is the most diversified with several foliage of beech and deciduous oaks, while diversified Juglandaceae contribute mainly as abundant leaf remains of Carya, Pterocarya and Juglans; Ulmaceae with numerous leave of two Zelkova species, and also Ulmus. Various other deciduous dicotyledonous such as Alnus, Betula, Carpinus, Populus, Acer laetum and A. interrigenum are well documented. Leguminosae are recorded by a small number of leaflet imprints. Evergreen shrubs of Buxaceae (Buxus pliocenica) are scarce. All these taxa contribute to a rich biodiversity of these Pliocene assemblages. All three sites point towards riverine forest habitats dominated by hygrophilic diversified woody plants while in the surrounding plains and slopes the thermophilic elements were scarce and mesophilic taxa abundant as temperate elements. This vegetation can be compared with mixed mesophytic forests depicting a climate cooling during the two considered periods (ca. 4.46 and 3.95 Ma).     

History of Late Holocene vegetation at Quintana Roo,Caribbean coast of Mexico

A pollen record of a Late Holocene sediment core from the Mexican Caribbean coast (Quintana Roo) shows the development and changes of a mangrove system. Humid conditions seem to have persisted for the period approximately 2500–1500 ¹⁴C yr BP (pollen zone I), and mangrove Rhizophora mangle dominated with a good representation of elements from the nearby semi-evergreen tropical forest. During the period approximately 1500–1200 ¹⁴C yr BP (pollen zone II) the mangrove Conocarpus erecta dominated. R. mangle almost disappeared and other taxa appeared, suggesting drier climatic conditions and generally more open vegetation. This dry period coincided with the period of the Maya cultural decline. The following period (pollen zone III, approximately 1200–1000 ¹⁴C yr BP) was characterized by the recovery of R. mangle, indicating more humid conditions than in the preceding pollen zone. Pollen zone IV (approximately 1000 ¹⁴C yr BP till present) suggests a drier period reoccuring with C. erecta; this marks the transition to present day conditions.     

Equatorial Pacific sea surface temperatures, faunal patterns, and carbonate burial during the Pliocene

A high-resolution record of radiolarian faunal abundances from the eastern equatorial Pacific is compared to records of carbonate and noncarbonate burial to examine the evolution of eastern tropical Pacific climate processes during the Pliocene. These data provide a means to evaluate the sensitivity of the equatorial Pacific to the onset of Northern Hemisphere glaciation around 2.8−2.5 Ma, to the closure of the Isthmus of Panama around 4.4−3.2 Ma, and to orogeny-related weathering changes before 4.0 Ma. Radiolarian faunal assemblages and sea surface temperature (SST) estimates indicate a gradual cooling from early to late Pliocene, but no significant changes occur near the onset of northern hemisphere glaciation. Records of carbonate and noncarbonate mass accumulation show a long term decrease from the Miocene/Pliocene boundary to the upper Pliocene. Greater carbonate burial in the early Pliocene relative to the late Pliocene parallels a gradual cooling from early to late Pliocene, and may reflect changes related to Isthmus closure or widespread orogeny. No significant time domain changes are seen in the eastern equatorial Pacific that could be related to the onset of Northern Hemisphere glaciation.Evolutive spectral analyses of these equatorial Pacific climate parameters indicate that variance in SST and seasonality commonly concentrate at frequencies not linearly related to orbital variations. Furthermore, cross spectral comparisons with a high resolution benthic δ¹⁸O record indicate that the surface ocean and carbonate flux share little coherent variance with high latitude climate processes during the Pliocene. Given the high degree of chronostratigraphic control in these records, these results suggest that Milankovitch-band surface ocean processes as well as carbonate burial in the equatorial Pacific are decoupled from high latitude climate processes during the Pliocene.     

Revision of the fossil vole assemblage (Mammalia,Rodentia, Arvicolidae) from Pleistocene deposits at Kisláng,Hungary

Abstract: The species‐rich fossil vertebrate assemblage from Pleistocene sedimentary deposits at Kisláng, Hungary, was originally described as containing eight species of arvicolids, six of which were considered new. Re‐examination of the material in the collection of the Hungarian Geological Institute, consisting of most of the previously described material, including the six name‐bearing types and also further undescribed specimens, indicates that the taxa Kislangia rex, Mimomys cf. hassiacus, Mimomys coelodus, Mimomys pusillus, Mimomys tornensis, Pitymimomys sp., Borsodia newtoni, Lagurodon arankae and Allophaiomys deucalion are present. Most of these species are compatible with Early Pleistocene age close to the boundary between the Villányian and Biharian regional stages (MQR10, MQ1, c. 1.6–2.0 Ma). However, the specimen of Mimomys cf. hassiacus is of approximately mid‐Pliocene age (MN15 c. 3.6–4.0 Ma), and one of the Pitymimomys specimens is referable to P. stenokorys, described from the earliest Pleistocene (MNR2–MNR3, MN17 c. 2.3–2.4 Ma). The assemblage is therefore interpreted as derived from at least three different geological periods and because of reworking of material is considered unusable to characterize any particular stratigraphic level. These conclusions are placed in the context of historical and current biostratigraphies.     

Pliocene and early Pleistocene environments and climates of the western Snake River Plain, Idaho

Sedimentological, palynological, and magnetic susceptibility data provide paleoenvironmental and paleoclimatic information from a 989 ft (301 m) core of sediments from the upper Glenns Ferry and Bruneau Formations from near the town of Bruneau in Owyhee County, Idaho. Chronology is based on stratigraphic position, paleomagnetism, and biostratigraphic data, which collectively suggest a late Gauss Normal-Polarity Chron age for the Glenns Ferry sediments and a middle Matuyama Reversed-Polarity Chron age for the Bruneau sediments. A deep lake was present on the western Snake River Plain during the portions of the time represented by the Glenns Ferry Formation, and the mudstones of the lower half of the core were apparently deposited in this lake. The terminal regression of the Glenns Ferry lake may be represented in the Bruneau core by sandy mudstones and sands that overlie the deep-water mudstones. A cobble layer present in the core between the Glenns Ferry lake beds and those of the overlying Bruneau Formation may indicate through-flow by the ancestral Snake River.Palynological data from the Glenns Ferry sediments in the Bruneau core reveal a pollen flora similar to the modern regional pollen flora, with very rare occurrences of now-extirpated taxa common earlier in the Tertiary. Palynological data from the Pliocene portion of this core indicate conditions more moist than today, with cooler summers and perhaps warmer winters. Quasi-periodic fluctuations in coniferous pollen (primarily Pinus) versus arid steppe taxa (primarily Chenopodiaceae/Amar-anthus) indicate significant variations in moisture through the lower two-thirds of the Glenns Ferry portion of the core. Shorter wave-length fluctuations in magnetic susceptibility and (inversely) Artemisia may reflect variations in temperature or other unidentified climatic variables. The pollen spectra from the Bruneau Formation sediments in the Bruneau core are dominated by Artemisia and resemble those of the Wisconsinan glacial period on the Snake River Plain, and hence indicate cold and dry conditions during some portion of the early Pleistocene.The deep-water Glenns Ferry lacustrine episode appears to date between approximately 3.5 to 3.3 and 2.5 Ma, and thus occurred during the middle Pliocene period of warmer-than-modern global temperatures. Similar sustained wetter-than-present conditions occurred in the same age range at sites across the western U.S.A. from southern California and Arizona to northern California and Idaho. This moist period was apparently followed by an interval of regional arid conditions that persisted for several hundred thousand years.     

Diversification and extinction patterns among Neogene perimediterranean mammals

The best mammalian fossil record during the Neogene of Western Europe is that of the rodents, the most successful and diversified mammal order. The study of origination and extinction during the Neogene (24-3 Ma BP) in one of the best-documented areas, Spain and southern France, gives an insight into the dynamics of these communities and indicates the possible nature of the driving forces. Three main periods of time show a high rate of origination: the late Burdigalian (17.5 Ma BP), the early Vallesian (11.5-11 Ma BP) and the early Pliocene (4.2-3.8 Ma BP). Two of these high origination-rate periods are immediately followed by important extinction events during which all cohorts are deeply affected (11.5-11 Ma BP and 4.2-3.8 Ma BP). The most important extinction event seems to occur during the early Vallesian (11.5-11 Ma BP), which probably includes the middle/late Miocene boundary. At the Miocene/Pliocene boundary, and during the early Pliocene, the faunal turnover seems to become faster, inducing a strong decrease of the mean species duration. Whereas the main immigration event, which occurs at 17.5 Ma BP, can be related to other faunal migrations in terms of the closure of the Tethys, as it occurs also in eastern Africa and in southwest Asia, the middle/late Miocene boundary event may have been related to a period of ice growth in the Southern Hemisphere. The extinction event that affects the planktonic foraminifera at 12 Ma BP cannot be chronologically correlated to this southwestern European land-mammal extinction event, because the calibration of the marine fossil record during that time-span has to be precise. Some limited terrestrial faunal exchanges that occur during the Messinian between southwestern Europe and northwestern Africa do not deeply affect the general faunal dynamics. Both allochthonous cohorts of immigrants become rapidly extinct. Several endemic rodent faunas, indicating insular conditions, have been reported from the southern edge of the western European continent from the middle Miocene up to the Pliocene. All show low taxonomic diversity, strong endemism and short survival. Some of them, like those of the Gargano Islands during the late Miocene, underwent peculiar morphological changes and also speciation. The large number of rodent genera coevolving in the Gargano Islands is indicative of the large surface areas of these islands. The general geographic pattern of southwestern Europe during the Neogene may therefore correspond to a large continental province including Spain and southern France with some kind of fast-modifying archipelago on its southern rim.     

Evolutionary history of the Paradoxurus palm civets – a new model for Asian biogeography

Aim Using molecular data and dental features, we investigated the genetic and morphological diversity among species of palm civets in the genus Paradoxurus, with a focus on the common palm civet, Paradoxurus hermaphroditus (Carnivora, Viverridae), in order to address biogeographic scenarios and provide recommendations for a taxonomic revision. Location Asia: Pakistan to the Lesser Sunda Islands. Methods We investigated the genetic diversity within Paradoxurus using two mitochondrial (cytochrome b, control region) and one nuclear (intron 7 of the β‐fibrinogen) markers. We used samples from 85 individuals of P. hermaphroditus (including 20 museum specimens) and one representative of each of the other species in the genus Paradoxurus: Paradoxurus jerdoni and Paradoxurus zeylonensis. DNA sequences were analysed using phylogenetic and haplotype network methods, and divergence dates were estimated for the clades retrieved. Furthermore, we examined dental characters from a large series of specimens and compared the morphological variation with the molecular data. Results Our phylogenetic analyses revealed that P. hermaphroditus is paraphyletic. We identified three major lineages distributed: (1) in the Indian subcontinent, south China, Hainan and in areas above 200 m in Indochina; (2) in Peninsular Malaysia, Java, Sumatra and in areas below 200 m in Indochina; and (3) in Borneo, the Philippines and the Mentawai archipelago. Our morphological observations were congruent with these three molecular lineages. Divergence date estimates inferred a Pliocene origin for Paradoxurus (2.8–5.7 Ma), with the three main clades diversifying from the mid–Early Pliocene to the end of the Pliocene. We suggest that the flooding of the Isthmus of Kra during the Pliocene was a major event shaping the diversification of Paradoxurus palm civets. We also hypothesize that the elevational segregation of the two lineages on the mainland could have resulted from the vegetational changes that were induced by Late Pliocene glacial episodes. Main conclusions The Isthmus of Kra is a major boundary between two major lineages of P. hermaphroditus. There is a need for a taxonomic revision for P. hermaphroditus, and we suggest that this species should be split into at least three species.     

India at the cross-roads of human evolution

The Indian palaeoanthropological record, although patchy at the moment, is improving rapidly with every new find. This broad review attempts to provide an account of (a) the Late Miocene fossil apes and their gradual disappearance due to ecological shift from forest dominated to grassland dominated ecosystem around 9-8 Ma ago, (b) the Pliocene immigration/evolution of possible hominids and associated fauna, (c) the Pleistocene record of fossil hominins, associated fauna and artifacts, and (d) the Holocene time of permanent settlements and the genetic data from various human cultural groups within India. Around 13 Ma ago (late Middle Miocene) Siwalik forests saw the emergence of an orangutan-like primate Sivapithecus. By 8 Ma, this genus disappeared from the Siwalik region as its habitat started shrinking due to increased aridity influenced by global cooling and monsoon intensification. A contemporary and a close relative of Sivapithecus, Gigantopithecus (Indopithecus), the largest ape that ever-lived, made its first appearance at around 9 Ma. Other smaller primates that were pene-contemporaneous with these apes were Pliopithecus (Dendropithecus), Indraloris, Sivaladapis and Palaeotupia. The Late Pliocene and Early Pleistocene witnessed northern hemisphere glaciations, followed by the spread of arid conditions on a global scale, setting the stage for hominids to explore “Savanahastan”. With the prominent expansion of grassland environments from East Africa to China and Indonesia in the Pliocene, monkeys and baboons dispersed into the Indian subcontinent from Africa along with other mammals. Though debated, there are several claims of the presence of early hominins in this part of the world during the Late Pliocene, based primarily on the recovery of Palaeolithic tools. Fossils of our own ancestor and one of the first globe-trotters, early Homo erectus, has been documented from the Early Pleistocene of East Africa, Western Asia and Southeast Asia, thus indirectly pointing towards Indian subcontinent as a possible migration corridor between these regions. The only definite pre-Homo sapiens fossil hominin remains come from the Central Narmada Valley and are thought to be of Middle to late Pleistocene age, and the cranium has been shown to be closely linked to archaic Homo sapiens/H. heidelbergensis of Europe. Around ∼74,000 yrs ago, a super volcanic eruption in Sumatra caused the deposition of Youngest Toba Tephra, that covered large parts of the Indian peninsula. Just around this time anatomically-and-behaviorally modern humans or Homo sapiens possibly arrived into India as evidenced by the so called Middle and Upper Palaeolithic assemblages and associated symbolic evidence. The available genetic data reveals that the gene pool to which modern Indians races belong was extremely diverse and had variable mixed links with both European and Asian populations.     

Plio-Pleistocene climatic oscilations, Holarctic biogeography and speciation in an avian subfamily

Aim In this paper, I discuss the temporal and spatial aspects of historical biogeography and speciation in a widely distributed Holarctic subfamily of birds (Tetraoninae). Location Northern Holarctic. Results Using dated fossils, I calibrated the molecular clock for the mitochondrial control region at 7.23 ± 1.58% nucleotide divergence (maximum likelihood corrected) per million years. The data suggest that grouse (Tetraoninae) originated in the Middle Pliocene, 6.3 Ma. Grouse apparently originated in the northern part of western Nearctic, and Palearctic was colonized independently three times, first by the ancestor of all grouse in the Middle Pliocene, then by the ancestor of forest (Falcipennis, Tetrao and Lyrurus) and prairie (Centrocercus, Dendragapus and Tympanuchus) grouse in the Late Pliocene, and finally by the ancestral Lagopus in the Early Pleistocene. Only once Nearctic was colonized from Palearctic by a common ancestor of forest grouse. Sympatry and range symmetry were positively correlated with molecular divergence. These correlations suggest that peripatric isolation was the predominant mode of speciation throughout grouse history. Main conclusions Speciation events in grouse were driven by climatic oscillations of the Pliocene and Pleistocene. Isolation of small peripheral populations from widely distributed ancestors was the dominant mode of speciation in grouse. Isolations during interglacials both across Beringia, and in southern mountain areas when boreal habitats were restricted to high elevations, suggest an important role for vicariance in grouse speciation.     

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.     

New observations on the Late Miocene–Early Pliocene Lutrinae (Mustelidae: Carnivora,Mammalia) from the Middle Awash,Afar Rift,Ethiopia

New observations on the Late Miocene and Earliest Pliocene mustelids from the Middle Awash of Ethiopia are presented. The Middle Awash study area samples the last six million years of African vertebrate evolutionary history. Its Latest Miocene (Asa Koma Member of the Adu-Asa Formation, 5.54–5.77 Ma) and Earliest Pliocene (Kuseralee and Gawto Members of the Sagantole Formation, 5.2 and 4.85 Ma, respectively) deposits sample a number of large and small carnivore taxa among which mustelids are numerically abundant. Among the known Late Miocene and Early Pliocene mustelid genera, the Middle Awash Late Miocene documents the earliest Mellivora in eastern Africa and its likely first appearance in Africa, a new species of Plesiogulo, and a species of Vishnuonyx. The latter possibly represents the last appearance of this genus in Africa. Torolutra ougandensis is known from both the Late Miocene and Early Pliocene deposits of the Middle Awash. The genus Sivaonyx is represented by at least two species: S. ekecaman and S. aff. S. soriae. Most of the lutrine genera documented in the Middle Awash Late Miocene/Early Pliocene are also documented in contemporaneous sites of eastern Africa. The new observations presented here show that mustelids were more diverse in the Middle Awash Late Miocene and Early Pliocene than previously documented.     

An 18 million year record of vegetation and climate change in northwestern Canada and Alaska: tectonic and global climatic correlates

We reconstruct long-term vegetation/paleoclimatic trends, spanning the last 18 million years, in Alaska, Yukon and far western Northwest Territories. Twenty-one average percentage spectra for pollen and spores are assembled from eight surface/subsurface sections. The sections are dated independently or by correlation. Pollen and spore ratios indicate the direction of change in vegetation and climatic parameters — growing season temperature (T_est), tree canopy density (C_est) and paludification at study sites (P_est). A global warm peak ca. 15 Ma is shown by the abundance of thermophilous taxa, including Fagus and Quercus. A temperature decline immediately following 15 Ma parallels climatic reconstructions based on marine oxygen isotopes. Subsequent declines correlate to the Messinian event and the onset of late Pliocene-Pleistocene glaciation. After 7 Ma herbs and shrubs become more important elements of the palynological assemblages, suggesting a more continental, colder/drier climate. However, a late Pliocene warm interval is evident. Vegetation/climatic changes during the early to late Miocene show synchrony with, and are most economically attributable to, global events. After 7 Ma, vegetation/climate change is attributed primarily to latest Miocene-to-Pleistocene uplift of the Alaska Range and St. Elias Mts. The continuing influence of global climatic patterns is shown in the late Pliocene warm interval, despite uplift to the south. The opening of the Bering Strait ca. 3 Ma may have moderated the climate in the study area.     

Orycteropus (Tubulidentata, Mammalia) from Langebaanweg and Baard's Quarry, Early Pliocene of South Africa

Fossil teeth and bones of aardvarks are relatively common at Langebaanweg, an Early Pliocene site in western Cape Province, South Africa. The remains are compatible in size and most details of morphology to extant Orycteropus afer, and are the earliest fossils attributed to this species. Other Late Miocene to Early Pliocene localities in Africa have yielded smaller species of aardvarks, suggesting that the extant lineage evolved in southern Africa. Morphologically the genus Orycteropus has been remarkably conservative since at least the Early Miocene but it witnessed an overall increase in size through the Neogene. The species O. afer has been morphometrically stable since the Early Pliocene. These observations indicate that the evolutionary process in aardvarks is extremely bradytelic. To cite this article: M. Pickford, C. R. Palevol 4 (2005).