the overkill hypothesis as a plausible explanation for the extinctions of late wisconsin megafauna abstract the pulse of large mammal extinctions at the close of the last ice age was a pronounced ecological catastrophe in the western hemisphere available paleoenvironmental paleontological and archeological data are largely concordant with the overkill hypothesis proposing that human predation was the cause of these extinctions climatic explanations fail to postulate specific mechanisms accounting for the event s timing differential impact geographic extent and stratigraphic singularity lack of provisional acceptance of the overkill hypothesis when no viable alternatives exist may be in part because this unconventional hypothesis violates a strong sociocultural bias the image of prehistoric man as the noble savage

paleoecological analyses of lake sediments reveal prehistoric human impact on forests at anthony island unesco world heritage site queen charlotte islands haida gwaii canada pollen and plant macrofossil analyses of lake sediments from anthony island in the southern queen charlotte islands haida gwaii british columbia reveal 1800 yr of relatively stable temperate rainforest vegetation cupressaceae cedar pollen percentages and accumulation rates decline about 1000 cal yr bp coincident with occupation of the island by haida peoples who use thuja plicata western red cedar almost exclusively for house construction dugout canoes monumental poles and many other items anthropogenic disturbance offers the most likely explanation for the decline of t plicata

provenance of the southern junggar basin in the jurassic evidence from detrital zircon geochronology and depositional environments abstract the goal of this paper is to study the provenance of the southern junggar basin during the late triassic to early cretaceous based on the detrital u pb geochronology petrography and depositional environments eight sandstone samples from the upper triassic to lower cretaceous were collected for detrital zircon u pb dating a total of 794 effective u pb ages was obtained and divided into four groups 488 2537 ma basement zircons 328 482 ma subduction related magmatic zircons 254 322 ma post collisional magmatic zircons and 135 250 ma syndepositional magmatic zircons these ages relate to three stages of basin evolution 1 from the early to middle jurassic tian shan experienced continued exhumation accompanied by progressive southward expansion of the junggar basin and a peneplain was formed by the time xishanyao formation was deposited organic rich sediments formed in a delta environment were well developed in the southern junggar basin with source rocks gradually switching from post collisional volcanic rocks 295 307 ma with a peak age of 300 ma of the southern north tian shan to post collisional volcanic rocks of the central tian shan 280 320 ma with a peak age of 316 ma and then to subduction related island arc rocks 402 423 ma with a peak age of 415 ma of the central tian shan 2 during deposition of the toutunhe and qigu formations large scale volcanic activities occurred along the north tian shan fault source rocks at this time include syndepositional volcanic rocks 151 161 ma and post collisional volcanic rocks 290 320 ma of the north tian shan by the time of deposition of the kalazha formation tian shan experienced rapid tectonic uplift leading to rapid lake regression alluvial fans were well developed in the southern junggar basin with source rocks being the underlying sedimentary strata of the north margin of the north tian shan 3 during the early cretaceous exhumation of the tian shan and lake transgression in the junggar basin happened again shallow lake sediments were developed in the southern junggar basin with source rocks being subduction related volcanic rocks 339 419 ma with a peak age of 415 ma of the central tian shan and post collisional volcanic rocks 254 305 ma with a peak age of 298 ma of the north tian shan

the preservation potential of coastal coseismic and tsunami evidence observed following the 2012 mw 7 8 haida gwaii thrust earthquake abstract we describe near field coseismic and tsunami evidence collected following the 28 october 2012 m w 7 8 thrust earthquake that occurred offshore western haida gwaii british columbia and discuss factors that influence its extent and preservation potential observations indicate minor geomorphic and sedimentological impacts on the rugged and unpopulated west coast of the islands despite widespread coastal coseismic subsidence 0 5 m triggered landslides and tsunami waves exceeding 3 m in runup maximum 13 m along 230 km of coastline evidence left by the tsunami was minimal likely because it occurred during a low tide that restricted its onshore reach its flow depth and its capacity to entrain and transport significant amounts of clastic sediment sources of which are minimal or absent on the dominantly steep rocky coastline it is unlikely that subaerial evidence of coseismic subsidence and tsunami inundation will be recognizably recorded in the coastal stratigraphy of western haida gwaii due to the relatively small magnitude of subsidence a lack of suitable coastal environments such as tidal marshes to record paleoelevation differences sedimentation rates that are too low to bury a paleoseismic or paleotsunami record and long term relative sea level fall leading to erosion and bioturbation a higher preservation potential is likely for tsunami deposits in coastal lakes ponds and bogs as well as coseismic slope failure deposits offshore in lakes and in sheltered fjords our findings imply that large tsunamigenic earthquakes are likely undersampled in the paleoseismic record of haida gwaii and of other plate margins with similar characteristics

a new carnosaur dinosauria theropoda from the jurassic of xinjiang people s republic of china in 1987 a sino canadian expedition known as the dinosaur project china canada alberta ex terra discovered a large theropod skeleton in the upper jurassic shishugou formation of the junggar

sequence stratigraphy paleoclimate patterns and vertebrate fossil preservation in jurassiccretaceous strata of the junggar basin xinjiang autonomous region people s republic of china multi kilometre thick jurassic cretaceous age sedimentary successions exposed in the southern northwestern and northeastern regions of the junggar basin display a consistent and correlative stratigraphy comprising four stacked second order megasequences badaowan sangonghe shishugou and kalaza each consists of a basal erosional unconformity or discontinuity surface and lower middle and upper units that are interpreted as forestepping backstepping and aggradational systems tracts respectively each megasequence is interpreted as recording an upsection shift from active tectonism and uplift to tectonic quiescence with associated changes in crustal response and sediment supply basin wide analysis of megasequences indicates that tectonism was intermittent and regionally variable a maximum phase of subsidence and sediment accommodation is recorded in the middle unit of each megasequence and correlates with a notable abundance of fossil vertebrates suggesting a primary tectonic and basin response

surface modification on bone trampling versus butchery abstract previous researchers have reported difficulties in distinguishing between surface marks on bone formed by sedimentary abrasion and those inflicted while butchering trampling by large ungulates and humans has been credited with producing pseudocut marks natural alterations to the bone that mimic cultural ones the purposes of this research are 1 to re examine trampling as a taphonomic process and 2 to suggest criteria useful for distinguishing sedimentary abrasion including trampling from butchery macroscopic and microscopic comparison of experimentally trampled bones and those which have had soft tissue removed with a flint tool demonstrate significant differences between the surface modifications produced by the two processes

taphonomy of the west runton mammoth abstract a substantially complete skeleton of a huge male mammoth mammuthus trogontherii estimated weight in life 9 tonnes was excavated from the west runton freshwater bed the cromerian stratotype at west runton on the north sea coast of norfolk uk over the period 1990 1995 the high standard of excavation of the skeleton and subsequent careful preparation and conservation provides much detailed evidence relevant to the taphonomic history of the mammoth assemblage the wear on the molars indicates that it was about 41 years old at the time of death compared with a life expectancy of about 64 so that it had died prematurely the fact that the west runton mammoth had sustained a severe injury to its right knee which would have left it disabled and debilitated might have led indirectly to its premature demise the dead animal appears to have lain on its right side in shallow water and waterlogged silts and soon after death the skin probably began to split exposing the ribs on the left side and the ends of the neural spines of the vertebrae to scavenging by spotted hyaenas and perhaps also other animals the feet were also extensively chewed at an early stage subsequently the skeleton appears to have been dismembered and scattered the smaller bones probably by scavengers and hyaenas further chewed the bones at various stages hyaena coprolites were deposited around the carcass other mammoths like modern elephants probably attracted to the remains of their own kind were presumably responsible for moving the larger and heavier bones skull and tusks and removing the left tusk from the skull they also appear to have extensively trampled the site pushing bones down into the sediment and producing numerous scratches inferred trampling marks the mandible and left ulna were subaerially weathered where they protruded above the water and silt while the similarly exposed top of the skull disintegrated in situ as the silt built up around it the west runton mammoth and associated finds provide unique information on the palaeobiology of both spotted hyaena crocuta crocuta and steppe mammoth m trogontherii in the early middle pleistocene

characterization of recent marks produced on fossil bone surface during sullegic and trephic processes and their influence on taphonomic studies abstract different taphonomic processes throughout the history of a fossil assemblage may preserve modify or destroy particular palaeobiological traits but these processes always increase taphonomic information of the past similarly fossils are affected during later stages of taphonomic history i e excavation preparation study and storage of fossils known as sullegic and trephic phases tools used during excavation and preparation of fossils can damage them and produce marks on their surface some of these recent marks highly mimic taphonomic marks produced before excavation both modern and fossil marks lead to misinterpretations and erroneous conclusions when similarities are not clearly detected in order to distinguish recent from ancient marks several diagnostic criteria resulting from experimental work are described in this paper

the timing of late pleistocene mammalian extinctions in north america more than 375 14c dates from 150 fossil sites in north america have been analyzed to evaluate the question of extinction of late pleistocene megafauna when critically evaluated no 14c ages for any extinct pleistocene genera are younger than 10 000 yr b p

taphonomic modes in the maastrichtian continental deposits of the haţeg basin romania palaeoecological and palaeobiological inferences abstract the uppermost cretaceous continental deposits of the ha eg basin sw romania have yielded a high diversity vertebrate assemblage including the dwarf insular dinosaurs of nopcsa in 1902 franz nopcsa was the first to comment on the preservation patterns of vertebrate fossils suggesting that the most important fossil accumulations which he simply referred to as fossiliferous pockets were the result of the predatory activity of crocodilians crocodilian feeding grounds recent investigations of the fossil occurrences within the ha eg basin revealed a much wider range of taphonomic modes from microfossil bonebeds to isolated partially articulated skeletons than previously believed the survey of the vertebrate accumulation types and their sedimentary context documents a wide range of processes responsible for their genesis operating within a fluvial dominated upland setting study of the individual fossil accumulations yields important information on the palaeoecology composition of local biocenoses trophic interactions and palaeobiology social behaviour habitat preferences of the ha eg fossil assemblage

a 14 000 year vegetation history of a hypermaritime island on the outer pacific coast of canada based on fossil pollen spores and conifer stomata abstract pollen and conifer stomata analyses of lake sediments from hippa island on the north coast of british columbia were used to reconstruct the vegetation history of this small hypermaritime island between 14 000 and 13 230 cal yr bp the island supported diverse herb shrub communities dominated by cyperaceae artemisia and salix pinus contorta and picea sitchensis stomata indicate that these conifers were present among the herb shrub communities likely as scattered individuals transition to open p contorta woodland by 13 000 cal yr bp was followed by increases in alnus viridis alnus rubra and p sitchensis after 12 000 cal yr bp pinus dominated communities were replaced by dense p sitchensis and tsuga heterophylla forest with lysichiton americanus and fern understory thuja plicata stomata indicate that this species was present by 8700 cal yr bp but the pollen record suggests that its populations did not expand to dominate regional rainforests along with tsuga and picea until after 6600 cal yr bp conifer stomata indicate that species may be locally present for hundreds to thousands of years before pollen exceed thresholds routinely used to infer local species arrival when combined pollen and conifer stomata can provide a more accurate record of paleovegetation than either when used alone

a 1500 year record of temperature and glacial response inferred from varved iceberg lake southcentral alaska we present a varve thickness chronology from glacier dammed iceberg lake in the southern alaska icefields radiogenic evidence confirms that laminations are annual and record continuous sediment deposition from a d 442 to a d 1998 varve thickness is positively correlated with northern hemisphere temperature trends and more strongly with a local 600 yr long tree ring width chronology varve thickness increases in warm summers because of higher melt runoff and sediment transport as expected but also because shrinkage of the glacier dam allows shoreline regression that concentrates sediment in the smaller lake varve thickness provides a sensitive record of relative changes in warm season temperatures relative to the entire record temperatures implied by this chronology were lowest around a d 600 warm between a d 1000 and a d 1300 cooler between a d 1500 and a d 1850 and have increased dramatically since then combined with stratigraphic evidence that contemporary jokulhlaups which began in 1999 are unprecedented since at least a d 442 this record suggests that 20th century warming is more intense and accompanied by more extensive glacier retreat than the medieval warm period or any other time in the last 1500 yr

new material of xinjiangchelys reptilia testudines from the late jurassic qigu formation shishugou group of the pingfengshan locality junggar basin xinjiang the late jurassic qigu formation of the shishugou group in the pingfengshan locality contains a vertebrate fauna dominated by two taxa of turtles both members of the genus xinjiangchelys one of these xinjiangchelys latimarginalis young and chow 1953 is well represented by a series of specimens the second is specifically indeterminate and is represented by only a single fragmentary specimen but is distinctive in having a long narrow plastral lobe derived features of xinjiangchelys that separate it from plesiochelys include the presence of a loose connection between the plastron and carapace with pegs on the plastron fitting in sockets on the peripherals the extension of the pleural marginal sulcus onto costals one to five the dorsal thickening of the lateral edges of peripherals two to seven the highly expanded seventh to eleventh peripherals the extension of the anal scute to the hypoplastron xiphiplastron suture or onto the hypoplastron a reduction in length of the first dorsal rib and the

dental anatomy of the apex predator sinraptor dongi theropoda allosauroidea from the late jurassic of china the dental morphology of the holotype of the theropod sinraptor dongi from the jurassic shishugou formation of china is comprehensively described we highlight a combination of dental features that

chronologic and environmental implications of a new genus of fossil deer from late wisconsin deposits at toronto canada abstract a new cervine deer torontoceros hypogaeus described from a partial cranium with portions of the main antler beams has been recovered from deposits of early lake ontario age on the exposed bench of glacial lake iroquois at toronto ontario canada the deer was about the size of a caribou has heavy antlers that lie chiefly in a nearly horizontal plane and its beams are bowed anteriorly the tines are not flattened the brow tines are asymmetrical and no evidence of surface roughening or palmation of the beam is found a 14 c date of 11 315 325 yr b p obtained on the antler allows the date at which glacial lake iroquois drained to be revised to before 11 400 yr b p spruce picea pine pinus and sedges cyperaceae are major components of the associated pollen spectrum which implies a typically interstadial or postglacial climate in which mixed forests grew in the toronto area

a theropod dinosaur feeding site from the upper jurassic of the junggar basin nw china abstract direct evidence for theropod feeding behaviour is rare in the fossil record and mainly limited to bite marks on bones here we describe a dinosaur assemblage from the lower part of the early late jurassic qigu formation at liuhuanggou gorge southern junggar basin nw china which has yielded fragmentary remains of a large sauropod as well as four teeth of large sized theropods and one tooth of a small sized theropod the sauropod bones show numerous bite marks that can be confidently linked to the large sized theropod probably a metriacanthosaurid the abundance of the theropod bite marks on a single skeleton indicates that the sauropod carcass was probably fed on extensively some bones are completely crushed and occur in patches of hundreds of tiny individual fragments indicating that they were trampled repeatedly by large dinosaurs both the feeding traces and the trampling suggests that the sauropod carcass was exposed for a substantial amount of time before it was finally buried within the deposits of a well drained floodplain the traces and the distinct preservation of the sauropod remains offer valuable insights into the feeding behaviour of large sized theropods within late jurassic continental ecosystems

a sauropod skeleton associated with theropod teeth in the upper jurassic of thailand remarks on the taphonomic and palaeoecological significance of such associations abstract the association of a partial sauropod skeleton with carnosaur teeth is described from the late jurassic sao khua formation of northeastern thailand this association is reminiscent of similar instances reported from the upper jurassic of western north america and east africa and can best be explained by dismemberment of a sauropod carcass by carnosaurs this type of evidence does not indicate whether the sauropod was killed by carnosaurs or whether the carnosaurs merely acted as scavengers the sauropod skeleton carnosaur teeth association can be used as a taphonomic indicator of a lack of post mortem transportation this in turn can lead to palaeogeographical conclusions as exemplified by the case of the damparis dinosaurs late jurassic of france the occurrence of which indicates in situ immersion

a high resolution marine palynological record from the central mainland coast of british columbia canada evidence for a mid late holocene dry climate interval abstract sediments collected in a 12 m long core vec02a04 obtained from frederick sound in the seymour belize inlet complex of british columbia were deposited between ca 4540 cal yr bp and ca 1090 cal yr bp in primarily dysoxic conditions the sediments are characterized by alternating intervals of fine grained massive and laminated units laminated sediments consist of light coloured diatom rich layers deposited during summer and dark coloured mineral rich layers deposited during winter laminated sediments are most common in portions of the core deposited between ca 2840 cal yr bp and ca 1820 cal yr bp and correspond to a decline in the relative abundance and pollen accumulation rate of cupressaceae pollen between ca 3190 cal yr bp and ca 2250 cal yr bp the preservation of laminated units and decline of cupressaceae pollen at this time suggest that a drier and possibly cooler climate punctuated otherwise wet and temperate late holocene conditions in the seymour belize inlet complex we correlate the occurrence of the mid late holocene dry climate interval documented in frederick sound to dynamics in the relative position and intensity of the aleutian low pressure system and suggest that climate change associated with dynamics of this semi permanent air mass affected primary productivity and vegetation of the seymour belize inlet complex

taphonomical and palaeoecological investigation of the late cretaceous maastrichtian tustea vertebrate assemblage romania haţeg basin insights into a unique dinosaur nesting locality abstract the tustea vertebrate locality at oltoane hill northwestern part of the ha eg basin romania has provided a rich and diverse assemblage of late cretaceous maastrichtian continental vertebrates more than 800 vertebrate fossils were recovered from this locality the isolated and associated remains represent 21 different taxa including amphibians turtles lizards snakes crocodyliforms pterosaurs dinosaurs and mammals the local assemblage is overwhelmingly dominated by dinosaurs with the rhabdodontid zalmoxes as the most abundant taxon the bonebeds that yielded this fossil material occur in a stacked series of mudstone calcrete units belonging to the middle member of the densus ciula formation the taphonomical investigations suggest that the tustea assemblage is made up of attritionally accumulated politaxic remains and that it is a parautochthonous assemblage with no evidence for significant bone transport or reworking according to the synthesis of all available field data two outstanding fossiliferous levels can be identified within the tustea locality where megaloolithus eggs and hadrosauroid hatchling material are preserved together recognized here as two superposed nesting grounds such co occurrence was considered controversial since there is a long standing and quasi general consensus that eggs of the megaloolithus oogenus were laid by titanosaurian sauropods we present several alternative scenarios to account for the co occurrence of telmatosaurus hatchling remains and megaloolithid eggs in the nesting horizons and explore these alternative hypotheses by weighing the arguments supporting or contradicting them the burden of evidence derived from our sedimentological taphonomical and palaeoecological investigations at tustea is still in favour of the autochthony of the hatchlings preserved within their own nesting grounds whereas there is no such support for a titanosaurian origin of the tu tea megaloolithid eggs

an azhdarchid pterosaur eaten by a velociraptorine theropod tooth marked bones are more common in the fossil record than published accounts would lead us to believe but with rare exceptions the animals that made the marks cannot be identified a partial s

global surface temperatures over the past two millennia 1 we present reconstructions of northern and southern hemisphere mean surface temperature over the past two millennia based on high resolution proxy temperature data which retain millennial scale variability these reconstructions indicate that late 20th century warmth is unprecedented for at least roughly the past two millennia for the northern hemisphere conclusions for the southern hemisphere and global mean temperature are limited by the sparseness of available proxy data in the southern hemisphere at present

bioerosion on vertebrate remains from the upper cretaceous of the haţeg basin romania and its taphonomic implications abstract bioerosion on fossil bones offers significant insights into both trophic relationships of ancient ecosystems and vertebrate taphonomy here we report six distinct trace fossil categories identified on isolated turtle crocodyliform and dinosaur remains from the upper cretaceous sinpetru formation of the ha eg basin romania for which five different probable tracemakers are identified 1 termites 2 dermestid beetles 3 multituberculate mammals 4 ziphodont theropod dinosaurs or crocodyliforms and 5 plants this extraordinary diversity of bioerosional trace fossils on vertebrate remains reveals insect vertebrate as well as vertebrate vertebrate interactions previously undocumented in the continental uppermost cretaceous of romania the association between different traces especially since many of these are superimposed on top of each other allows the reconstruction of the detailed taphonomic history of the specimens indicating four different taphonomic pathways the vertebrate remains with trace fossils described here were most likely exposed to post mortem biotic interactions for a prolonged time period before they were transported and or trampled and finally buried in the palaeoenvironmental context of a heterogeneous braided river system with low lying wetlands and more elevated drylands the death of the vertebrates as well as the scavenging likely occurred on the drylands

radiocarbon dates from anthony island queen charlotte islands and their geological and archaeological significance seven samples of peat or wood were collected from four small sedimentary basins on anthony island elevations of these sites range between 31 1 and 2 5 m above mean sea level radiocarbon dates from these indicate that sea level has not exceeded 31 1 m since 12 300 years ago furthermore sea level has been less than 12 7 m above mean sea level since about 4000 bp and has declined at about 2 5 m 1000 years a well defined scarp with relict surge channels and sea caves may define the postglacial mean sea level maximum at about 12 15 m a date of 1750 120 bp at the base of a pond is particularly significant since it places a maximum possible age on the skung gwai village site unesco world heritage site and other known archaeological sites near present sea level

late quaternary dynamics of forest vegetation on northern vancouver island british columbia canada abstract pollen analysis of radiocarbon dated lake sediment from northern vancouver island southwest british columbia reveals regional changes in forest vegetation over the last 12 200 14c yr 14 900 cal yr between at least 12 200 and 11 700 14c yr bp 14 900 13 930 cal yr bp open woodlands were dominated by pinus contorta alnus crispa and various ferns as p contorta decreased in abundance alnus rubra and more shade tolerant conifers i e picea and tsuga mertensiana increased increases in t mertensiana p contorta and a crispa pollen accumulation rates pars between 10 600 and 10 400 14c yr bp 11 660 11 480 cal yr bp reflect a cool and moist climate during the younger dryas chronozone orbitally induced warming around 10 000 14c yr bp 11 090 cal yr bp allowed the northward extension of pseudotsuga menziesii although picea tsuga heterophylla and a rubra dominated early holocene forests by 7500 14c yr bp 8215 cal yr bp shade tolerant t heterophylla was the dominant forest tree cupressaceae thuja plicata and chamaecyparis nootkatensis was present by 7500 14c yr bp but reached its maximum after 3500 14c yr bp 3600 cal yr bp when a cooler and wetter regional climate facilitated the development of temperate rainforest the highest rates of vegetation change are associated with lateglacial climate change and species with rapid growth rates and short life spans

a large mamenchisaurid from the junggar basin xinjiang people s republic of china an articulated neck of a large mature sauropod with enormously elongated cervical ribs was discovered in strata of late jurassic age in the eastern junggar basin xinjiang people s republic of china the animal is estimated to have originally measured 26 m in length but was lightly proportioned relative to brachiosaurus and apatosaurus rudimentary spines on the anteriormost cervical vertebrae diagnose a previously undescribed species of mamenchisaurus cranial parts associated with the neck do not support a close relationship with diplodocids mamenchisaurs apparently belong to an endemic jurassic radiation of asian sauropods

holocene tree line and climate change on the queen charlotte islands canada palynological study of two subalpine ponds on the queen charlotte islands reveals changes in tree line and climate during the holocene the findings agree with previous reconstructions from nearby louise pond on the queen charlotte islands that suggest a warmer than present climate and higher than present tree lines in the early holocene ca 9600 660014c yr b p basal ages at sc1 pond and shangri la bog indicate that the basins did not hold permanent water before 720014c yr b p consistent with a warmer and drier early holocene previously inferred from louise pond pollen and plant macrofossils indicate the initial establishment of subalpine conditions by 6090 9014c yr b p similar to the 5790 13014c yr b p age for cooling inferred from louise pond conditions similar to present were established at sc1 pond by 3460 10014c yr b p confirming the previous estimate of 340014c yr b p at louise pond this 340014c yr b p vegetation shift on the queen charlotte islands corresponds with the beginning of the tiedemann glacial advance in the south coastal mountains of british columbia ca 330014c yr b p the peyto and robson glacial advances between 3300 and 280014c yr b p in the rocky mountains and climatic cooling inferred from palynological studies throughout southern british columbia northern washington and southeast alaska these findings confirm that changes in regional climate influenced changes in vegetation in coastal british columbia