Large- and small-mammal distribution patterns and chronostratigraphic boundaries from the Late Pliocene to the Middle Pleistocene of the Italian peninsula

Over the last 50 years the studies on terrestrial mammals of the Italian peninsula have provided a large volume of data and a more detailed knowledge of faunal events during the Late Pliocene and Quaternary. Moreover geological, sedimentological, palynological and magnetostratigraphical investigations on the Pliocene–Pleistocene continental sedimentary basins have yielded the possibility of a detailed calibration of the faunal successions. Thus, palaeontologists have been able to reconstruct faunal sequences and to propose biochronological scales based on large and small mammals, respectively. In the present contribution an integration of the two biochronological scales is proposed, and the successions of bioevents are carefully compared. This integrated approach allows the constraint of the sequence of large- and small-mammal events in a more reliable way, and therefore it results in a more detailed and consistent chronological use of mammalian assemblages. Particular attention is paid to the faunal changes that correspond to the Middle–Late Pliocene (2.6 ma), Pliocene–Pleistocene (1.8 ma) and Early–Middle Pleistocene (Gauss–Matuyama transition) chronostratigraphical boundaries.     

Late Pleistocene large mammal faunas from the Urals

The 121 local faunas of large mammals from Late Pleistocene sites of the South (56–51°N), Middle (59–56°N) and North (64–59°N) Urals have been studied. All local faunas were combined into eight chronological groups on the basis of radiocarbon dates and the evolutionary level of rodents present in them. On the basis of species composition analysis of the faunas, three chronological complexes have been distinguished: Mikulino, Early–Middle Valdai and Late Valdai. The first is characterized by the presence of Hystrix vinogradovi and Ursus thibetanus; the second, by the presence of a large form of horse (Equus (E.) cf. latipes), Crocuta crocuta, Ursus spelaeus and U. savini; the third, by the presence of a small horse (E. uralensis) and absence of U. spelaeus, U. savini and C. crocuta. The latter two complexes were represented by three geographical variants: southern (South Urals), northern (North Urals) and transitional (Middle Urals). Differences between theriocomplexes are related to changes in morphology and areas and extinctions of a series of species. The existence of chronological theriocomplexes and their geographical variants was determined by chronological and geographical change in structure of paleophytocoenoses. It should be noted that the role of human in changes of chronological complexes and species extinctions in the Late Pleistocene has not been demonstrated in the Urals. In the Urals U. savini probably became extinct at the end of the Middle Valdai, C. crocuta at the beginning of the last glacial maximum (LGM), U. spelaeus at the end of the LGM, Coelodonta antiquitatis at the beginning of the Preboreal and Megaloceros giganteus at the middle of the Atlantic.     

Late Pliocene to Early Pleistocene productivity in the Arabian Sea

The stable isotopic compositions of organic C and N and the organic carbon (OC) content of the Oman Margin (ODP Site 724) sediments, ranging from Pliocene to Early Pleistocene in age, are used to infer palaeoproductivity in the area. At the boundary between the Pliocene and the Pleistocene, the amount of organic matter preserved is low compared to other periods before and after this transition period. This low OC content is associated with depleted N and C isotope values. This may indicate low primary productivity as a result of a diminished supply of nutrients caused by weak coastal upwelling. Higher amounts of OC, in conjunction with enrichment in the isotopic compositions of both organic C and N before and after the Pliocene-Pleistocene transition period, are likely to be a consequence of an increase in primary productivity, which resulted from a higher nutrient supply. However, a higher amount of OC may have resulted from enhanced preservation. The enhanced preservation may have resulted from an intrusion of highly saline waters from the Res Sea and Persian Gulf and/or restricted circulation.     

Early–Middle Pleistocene environmental changes and human evolution in the Italian peninsula

This paper is aimed to elucidate the ecological scenario in Italy in the Early to Middle Pleistocene, when species of the genus Homo are known to spread across Europe in two distinct waves: earlier than 1.2 Ma and at about 600 ka, respectively. This topic represents both (1) a fundamental aspect for a better understanding of the factors that allowed humans to colonize the middle latitudes of Eurasia, and (2) a reasonable frontier for current Quaternary palaeobiology, thanks to increasing knowledge of regional and local patterns. As for Italy, a combination of palaeobotanical and palaeontological data sets shows on the one hand a general complexity in both space and time, and on the other hand changes of considerable importance within and among the biological communities. These changes had a major importance during the worldwide change in the Earth climatic system known as “Middle Pleistocene Revolution”, which according to our data culminates with crucial effects of the extreme conditions of MIS 16. Subsequently, during great part of the Middle Pleistocene, the peculiar features of the Italian territory may have favoured isolation and a local persistence of plant populations and possibly mammal taxa, humans included, as for instance suggested by the corrected chronology of the Ceprano calvarium.     

Towards a chronology of the Late Pleistocene in the northern Alpine Foreland

Dating results from terrestrial records in the northern foreland of the Alps have been compiled in order to establish an independent chronostratigraphy for the climate history of this region. U/Th dates of peat deposited during the final phase of the Last Interglacial indicate that it lasted until at least c. 115 000 yr ago. The Early Würmian started with a period of severe cold climate causing a substitution of forest by tundra-like vegetation. It is assumed that during this period glaciers advanced to the margin of the foreland of at least the Western Alps. Sediments attributed to this glaciation are dated to about 103 000 yr. Three subsequent interstadials, all characterized by coniferous forest, were interrupted by cold stadials with steppe to tundra-like vegetation. The first interstadial is dated to about 95 000 yr. There is evidence for an interstadial with open coniferous woodland and three phases of steppe vegetation during the Middle Würmian, between c. 50000 and 30 000 yr ago. The last glaciation of the Alpine Foreland reached its maximum extension between 24 000 and 21 500 yr and glaciers rapidly collapsed before ˜17 500 yr ago. A series of minor re-advances during the Lateglacial is reported from within the Alps, but the glaciers barely reached the main Alpine valleys during this time. The last of these advances formed the Egesen moraine and occurred at about 11 800 yr ago during the Younger Dryas.     

The missing Myopus: plugging the gaps in Late Pleistocene small mammal identification in western Europe with geometric morphometrics

Lemmus and Myopus are two lemming species with distinct habitat requirements but which show very similar dental morphologies. They are thus extremely difficult to distinguish from one another in the fossil record on the basis of their dental remains, leading to poor understanding of the palaeobiogeographical evolution of Myopus as well as inaccurate palaeoenvrionmental reconstructions. Currently, the presence of Myopus in the fossil register from the Pleistocene is still debated and no firm occurrence of this lemming in western Europe has yet been confirmed for the Late Pleistocene. In this paper, we used geometric morphometrics on modern material to establish morphological differences between Lemmus and Myopus teeth (first lower and third upper molars). Morphological data were then used to build a robust linear discriminant model able to confidently classify isolated teeth of these two genera, and finally, linear discriminant models were used on fossil remains of Lemmus/Myopus from two Late Pleistocene archaeological/palaeontological sites (Grotte des Gorges and Gully Cave). This study demonstrates, for the first time, the presence of Myopus schisticolor in west European Late Pleistocene sites between the end of Marine Isotope Stage 3 and the beginning of the Holocene, during climatic events that favoured the development of taiga forest of birch and pine in these regions.     

Late Pleistocene chronology and environment of the “ice-free corridor” of northwestern Alberta

Pollen and macrofossil analyses of two radiocarbon-dated lake sediment cores in the upper Peace River district were used to investigate the controversial late-glacial geochronology of the “ice-free corridor.” The basal mineral-rich sediments contain reworked, radiogenically “dead” palynomorphs, as well as intrusive “modern” carbon. Analyses of the basal sediments from Boone Lake show that two ¹⁴C ages greater than 12,000 yr B.P. are spuriously old due to contamination by organic matter of Cretaceous age. The data support occlusion or near occlusion of Laurentide and Cordilleran ice in the Peace River area during the late Wisconsinan period. The sediment record began around 12.000 yr B.P. in the ice-dammed and enlarged Boone Lake. An initially open, sedge-dominated cover was invaded by sage, willow, grass, and poplar by 11,700 yr B.P., suggesting that a habitable landscape has existed in the area for at least 12 millennia. The data, however, do not support the ice-free corridor arguments of B. O. K. Reeves (1973, Arctic and Alpine Research5,1–16; 1983, In “Quaternary Coastlines and Marine Archaeology: Towards the Prehistory of Land Bridges and Continental Shelves” (P. M. Masters and N. C. Fleming, Eds.), pp. 389–411. Academic Press. New York), who suggests that ice occlusion did not occur in the Peace River Valley during the last 55,000 yr.     

Late Pleistocene glacial chronology of the Taylor Valley,Antarctica, and the global climate

Carbonate-rich lacustrine and deltaic deposits, containing thin beds of finely laminated carbonates and thick beds of silt, crop out at several sites in the Taylor Valley and have been encountered in cores obtained by the Dry Valley Drilling Project (DVDP). Fragments of the more indurated carbonate beds have widespread occurrence as part of the desert “lag gravel” which covers much of the valley floor. Analysis of the carbonates suggests that they were deposited as algal limestones from waters derived from the East Antarctic Ice Sheet via the Taylor Glacier at times which correspond to the previous three global interglacial periods, as evidenced by the ice volumes deduced from oxygen-isotopic analysis of oceanic cores. The lacustrine carbonates have been found up to 30 km beyond the present terminus of the Taylor Glacier, and up to 100 m above the level of Lake Bonney, into which the Taylor Glacier at present discharges. It is concluded that the Taylor Glacier has advanced during each of the previous three interglaciations, and it is suggested that this has been caused by a thickening of the East Antarctic Ice Sheet during the interglaciations.     

An optical age chronology of Late Pleistocene fluvial deposits in the northern lower Mississippi valley

The lower Mississippi valley (LMV) contains many large braided channel belts that are preserved west of the Holocene floodplain. Previous efforts to establish geochronologic control on channel-belt construction have been hindered by the lack of organic material for radiocarbon dating. Luminescence techniques provide a burial date for the sediment itself and may prove useful in this context. Samples from three channel belts in the northern LMV were analyzed using the single aliquot-regenerative technique on 90–125 μm quartz. Optical ages (19.7–17.8, 16.1–15.0 and 12.5–12.1 ka) are consistent with geomorphic relationships and indicate that channel belts were formed in the late Pleistocene under glacial conditions. These optical ages provide the first detailed chronology of LMV channel-belt formation and are the first step towards developing a chronology for the entire LMV.     

Pleistocene decalcification of Late Pliocene Red Crag shelly sands from Walton-on-the-Naze, England

Uppermost sands of the Red Crag at Walton-on-the-Naze (Essex) and elsewhere in East Anglia have been decalcified to iron-stained quartz sands. In contrast, lower sands are only minimally altered and contain aragonitic and calcitic shells. Aragonitic shells are slightly dissolved (chalkified), but calcitic shells are unaffected. Cementation is limited to an addition of iron oxides, now mainly haematite, which also coat carbonate grains. Abundant iron-oxide fines in the upper decalcified sands were liberated from the coatings of shells; shells that have since dissolved. The diagenetic nature of the contact between decalcified upper and unaffected lower sands is evident where it transects cross-bedding. The contact is knife-sharp, even smoothly truncating large shells, and is usually planar and subhorizontal. Shelly sands immediately beneath the boundary contain similar amounts of aragonitic material, as do sands further below. Locally the decalcification boundary has been contorted by cryoturbation, implying that carbonate dissolution was a Pleistocene event. Decalcification probably occurred when the area was affected by permafrost. Lower sands were cemented by ice and protected from dissolution. Upper sands were above the ice table and subject to chemically aggressive waters during summer thaws. Decalcification is believed to have taken place during an episode of climate amelioration when downward retreat of the ice table accompanied replacement of tundra by boreal forest. Highly acidic and podzolic soils developed, beneath which shell-carbonate dissolved. Sharp based decalcified zones in Lowestoft Till and Devensian deposits in other parts of England can also be attributed to dissolution associated with permafrost.     

晚更新世以来内蒙古哈素海钻孔地层记录及其年龄

“河套古大湖”对于研究区域环境及气候演化具有重要的意义,然而,其形成与消亡的时代仍存在争议。依托于哈素海西南岸边获取的HSH钻孔,采用AMS14C、OSL测年方法确定了沉积物年代,结合岩心的岩性、沉积结构等特征,分析了哈素海的演化历史,并探讨了河套古大湖存亡的时期。结果表明,哈素海地区晚更新世以来的沉积环境主要经历了以下转变过程：150~70 ka为较稳定的湖泊,70~55 ka湖泊水位下降,为滨湖相沉积,55~27 ka为湖沼沉积,27~0 ka为滨湖相沉积。根据哈素海的沉积演化历史,结合河套盆地相关研究成果,认为河套古大湖早在150~110 ka就已形成,其后水位下降,直至55 ka之后,萎缩消亡,河套盆地局部地区形成湖沼沉积,但已不再是统一的大湖。研究结果对于深入探讨河套盆地演化历史乃至黄河的变迁具有重要意义。     

Late Pleistocene carbonate aeolianites on Mallorca, Western Mediterranean: a luminescence chronology

Coastal outcrops of Upper Pleistocene deposits in north-eastern Mallorca (Balearic Islands, Spain) have been examined and a chronological framework established using Optically Stimulated Luminescence (OSL) dating. The outcrops record a complex interaction between aeolian, colluvial and alluvial fan deposition that result in a variable stratigraphical architecture. Dating and facies analysis make it possible to identify four aeolian activity episodes during MIS 5c/b, 4 and 3, and also add to the understanding of the environmental history of north-eastern Mallorca over the last 100 ka. The new data suggest enhanced aeolian transport and dune formation during cold climatic intervals when sea level was low, sediment supply (exposed marine carbonate sediment) was high, winter windiness was high, and vegetation on coastal plains at a minimum.     

Variation and pattern in the responses of mammal faunas to Late Pleistocene climatic change in southeastern South Australia

We examined mammal occurrence and variability through the Late Pleistocene vertebrate fossil deposit of Grant Hall in Victoria Fossil Cave, Naracoorte, South Australia. To determine long‐term patterns of change, we compared the composition and relative abundance trends of the assemblage with a nearby Middle Pleistocene deposit in Cathedral Cave. Total species richness did not change through the Grant Hall sequence, dated from 93 ± 8 to 70 ± 5 ka. However, species relative abundances varied between ecologically divergent species, and in some cases between species that demonstrate similar environmental preferences. For some species this variation is comparable to that recorded in Cathedral Cave. Of those showing similar trends between the two deposits, the forest inhabitant, Pseudomys fumeus, recorded an 8.6% decline through Grant Hall, coincident with a 9.7% increase in the dry heath/mallee dweller Pseudomys apodemoides. These patterns indicate that climatic transition from relatively warm, moist to cooler, drier conditions impacted some species in similar ways through climatic cycles of the past. However, the majority of the fauna demonstrated complex responses that are individual and variable through time. Statistical tests of species trends from the Grant Hall assemblage caution that large fossil samples are required to validate patterns observed. Copyright © 2012 John Wiley & Sons, Ltd.     

Fault-plane solutions and seismicity of the Italian peninsula

A new fault-plane solution map of the Italian peninsula is presented in this paper. The earthquakes analyzed are included in the period 1905–1980, with magnitudes ranging 4–7, 75 earthquakes are located in the crust, while 31 are related to the deep and intermediate zone of the Calabrian arc. The large seismic events of the Italian peninsula are generally associated with normal faulting, while strike-slip motion is mostly related to small earthquakes, located along lateral segments of the mountain chain.The deep and intermediate earthquakes of the Tyrrhenian Sea indicate predominant down-dip compression, and strike-slip motion at the boundaries of this Benioff zone. This last is interpreted as a remnant of a subduction zone, active since Oligocene, extending to 500 km depth, with a very small lateral size (about 300 km). The present tectonics of this Benioff zone is strongly conditioned by the lateral bending, more so than the gravitational sinking process.The coexistence of thrust and normal faulting motion associated to the earthquakes, within a few tens of kilometers of each other, seems to be explained by the strong lateral inhomogeneities of the crustal rocks present in this region, more so than to the depth of the seismogenetic zone and the nature of the faulting process.     

Late Pleistocene remains of giant deer (Megaloceros giganteus Blumenbach) in Scandinavia: chronology and environment

This article presents new data on the Late Pleistocene giant deer, Megaloceros giganteus (Blumenbach), describing its distribution in time and space, geographical and sexual variation and general biology. Twenty‐three south Scandinavian fossils found in situ in lacustrine sediments or redeposited in glaciofluvial material form the basis of this investigation. Fourteen C dates show that the giant deer inhabited southern Scandinavia in the ice‐free late Middle Weichselian from c. 40000 to 28000 BP (the Sandnes Interstadial) and again in the Late Weichselian from c. 12000 to 10700 BP (Older Dryas, Allerød and early Younger Dryas Chronozones), corresponding to a calibrated range from c. 14300 to 12400 cal. yr BP. Osteometric analyses show that the Scandinavian giant deer belonged to the upper size range of the lateglacial Irish population and that a marked sexual dimorphism existed, the males being 10–11% larger than the females. Investigations furthermore point at an antler cycle similar to that among extant northern cervids, and subsequently at a rutting season in autumn. The skeletal remains also prove the occurrence of twin delivery and the possibility of reaching an ontogenetic age of at least 23 years. During both occurrences the Scandinavian giant deer population was part of the northernmost distribution of the species in Europe and the palaeogeographical settings and palaeoenvironmental conditions of the two periods show striking similarities. Clearly, the giant deer were able to colonize and survive in a landscape dominated by grasses and sedges with scattered shrubs and dwarf shrubs. They came as close as 200–250 km to the ice front and their distribution included coastal areas along a cold sea with drifting icebergs. They were present in the area at least from March until November. However, the pure arctic conditions created during the early phase of the Younger Dryas event led to a new local extinction around 10700 ¹⁴C yr BP. This was the beginning of a total Eurasian extinction which, at least in Europe, was completed before the Pleistocene/Holocene transition.     

Loess chronology of the Middle and Upper Pleistocene in Tadjikistan

The loess/paleosol sequences of Central Asia are continuous terrestrial records of the Quaternary period and enable detailed comparison with paleoclimatic archives such as marine and ice core records in order to reconstruct regional and global paleoclimatic and paleoecological development during the past 130?000 years. Thermoluminescence (TL) and infrared stimulated luminescence (IRSL) dating methods are applied to the extensively studied loess/paleosol sequence of the section at Darai Kalon/Chashmanigar, Tadjikistan, in order to determine a more accurate chronological framework and climatostratigraphic reconstruction for the last interglacial/glacial cycle. Luminescence dating suggests that the loess above the first pedocomplex from the top, PC1, accumulated during the last glacial period. A high accumulation rate of up to 1.20?m per 1000 years was determined for the last glacial loess, especially for the uppermost 5–8?m. PC1 formed during the last interglacial period (oxygen-isotope stage 5). The loess between PC1 and PC2 is designated to be of penultimate glacial deposition age. Infrared stimulated luminescence and TL age estimates are in agreement to 80?000 years before present (BP), indicating a long-distance transport of the aeolian dust prior to deposition. The upper numerical age-limit range is between 300?000 and 450?000 years. However, reliable dating of the loess older than 130?000 years is not possible due to age scatter between samples and an inadequate increase of paleodose with depth. This high-resolution dating study underlines the importance of the section at Darai Kalon and indicates that it is one of the most continuous loess/paleosol records of the Northern Hemisphere. The chronological results are particularly important for the reconstruction of the human evolution in Central Asia, suggesting much older age estimates than previously obtained for most of the archeological key sites associated with PC5 and PC4 in Tadjikistan.     

Late Pliocene to late Pleistocene environments preserved at the Palisades Site, central Yukon River, Alaska

The Palisades Site is an extensive silt-loam bluff complex on the central Yukon River preserving a nearly continuous record of the last 2 myr. Volcanic ash deposits present include the Old Crow (OCt; 140,000 yr), Sheep Creek (SCt; 190,000 yr), PA (2.02 myr), EC (ca. 2 myr), and Mining Camp (ca. 2 myr) tephras. Two new tephras, PAL and PAU, are geochemically similar to the PA and EC tephras and appear to be comagmatic. The PA tephra occurs in ice-wedge casts and solifluction deposits, marking the oldest occurrence of permafrost in central Alaska. Three buried forest horizons are present in association with dated tephras. The uppermost forest bed occurs immediately above the OCt; the middle forest horizon occurs below the SCt. The lowest forest bed occurs between the EC and the PA tephras, and correlates with the Dawson Cut Forest Bed. Plant taxa in all three peats are common elements of moist taiga forest found in lowlands of central Alaska today. Large mammal fossils are all from common late Pleistocene taxa. Those recovered in situ came from a single horizon radiocarbon dated to ca. 27,000 ¹⁴C yr B.P. The incongruous small mammal assemblage in that horizon reflects a diverse landscape with both wet and mesic environments.     

Sea‐level and climatic controls on Late Pleistocene coastal aeolianites in the Cap Bon peninsula,northeastern Tunisia

Elmejdoub, N., Mauz, B. & Jedoui, Y. 2010: Sea‐level and climatic controls on Late Pleistocene coastal aeolianites in the Cap Bon peninsula, northeastern Tunisia. Boreas, 10.1111/j.1502‐3885.2010.00162.x. ISSN 0300‐9483. The chronology of coastal dunes (aeolianites) along the western littoral of the Cap Bon peninsula (northeastern Tunisia) was investigated using an optical dating technique to examine their tentative correlation with the Marine Isotope Stage (MIS) record. These dunes, formed under a northwesterly wind regime and supplied by sand from the shore, are an indicator of sea‐level and climate changes. We obtained optically stimulated luminescence ages for these aeolianites ranging from 112±10 to 53±2 ka and clustering around the last interglacial period (～125–75 ka), implying that the former stratigraphic allocation of these dunes is inaccurate. The optical chronology suggests dune formation during MIS 5 in association with a sea level lower than today but higher than the glacial sea‐level lowstand.