Swedish Museum of Natural History
Not a member yet
1516 research outputs found
Sort by
Palaeovegetation and palaeoclimate changes across the Triassic–Jurassictransition in the Sichuan Basin, China
No full textThe Triassic–Jurassic transition interval is marked by enhanced biotic turnover rates in both marine and terrestrial realms. However, limited data from Asia hampers the understanding of global ecosystem response to the end-Triassic mass extinction event. Here, we present significant vegetation and climate changes across the Triassic–Jurassic transition in the eastern Tethys region (southern China). A detailed palynological study was performed from the Qilixia section of the Sichuan Basin, China, spanning the Upper Triassic (Norian–Rhaetian) (Xujiahe Formation) to the Lower Jurassic (Hettangian–Sinemurian) (lower Zhenzhuchong Formation). Five palynological assemblages reveal significant ecosystem fluctuations across the Triassic–Jurassic transition. Our study indicates a lowland fern flora and a warm and humid climate in the Late Triassic (Norian to Rhaetian), interrupted by a cooler interval at the Norian–Rhaetian transition, and followed by a mixed mid-storey forest under cooler and drier condition in the latest Rhaetian. This is followed by a fern-dominated lowland vegetation and a warmer and drier climate during the Triassic–Jurassic transition, and a flora with abundant cheirolepid conifers in the Hettangian–Sinemurian. These long term changes in vegetation and inferred climatic conditions are comparable with records from the western Tethyan realm, and possibly reflect global terrestrial environmental changes associated with Central Atlantic Magmatic Province volcanism during the Triassic–Jurassic transition
The Habitat of the Nascent Chicxulub Crater
No full textAn expanded sedimentary section provides an opportunity to elucidate conditions in the nascent Chicxulub crater during the hours to millennia after the Cretaceous‐Paleogene (K‐Pg) boundary impact. The sediments were deposited by tsunami followed by seiche waves as energy in the crater declined, culminating in a thin hemipelagic marlstone unit that contains atmospheric fallout. Seiche deposits are predominantly composed of calcite formed by decarbonation of the target limestone during impact followed by carbonation in the water column. Temperatures recorded by clumped isotopes of these carbonates are in excess of 70°C, with heat likely derived from the central impact melt pool. Yet, despite the turbidity and heat, waters within the nascent crater basin soon became a viable habitat for a remarkably diverse cross section of the food chain. The earliest seiche layers deposited with days or weeks of the impact contain earliest Danian nannoplankton and dinocyst survivors. The hemipelagic marlstone representing the subsequent years to a few millennia contains a nearly monogeneric calcareous dinoflagellate resting cyst assemblage suggesting deteriorating environmental conditions, with one interpretation involving low light levels in the impact aftermath. At the same horizon, microbial fossils indicate a thriving bacterial community and unique phosphatic fossils including appendages of pelagic crustaceans, coprolites andbacteria‐tunneled fish bone, suggesting that this rapid recovery of the base of the food chain may have supported the survival of larger, higher trophic‐level organisms. The extraordinarily diverse fossil assemblage indicates that the crater was a unique habitat in the immediate impact aftermath, possibly as aresult of heat and nutrients supplied by hydrothermal activity
Staminate inflorescences with in situ pollen from Eocene Baltic amber reveal high diversity in Fagaceae (oak family)
No full textEocene Baltic amber forms the largest amber deposit worldwide; however, its source vegetation and climateare much debated. Representatives of the oak family (Fagaceae) were abundant in the Baltic amber source areabased on numerous inclusions of staminate inflorescences or individual florets, previously assigned to Castanea andQuercus. However, the actual generic and infrageneric diversity of Fagaceae from Baltic amber remained unknown.Using flower characteristics and section-diagnostic in situ pollen of staminate inflorescences and detached floret inclusions,we describe 18 fossil-species of Fagaceae making this family by far the most diverse plant family preservedin Baltic amber. We substantiate the occurrence of the Castaneoideae, Quercoideae (Quercus sect. Cyclobalanopsis/ Lobatae; Q. sect. Lobatae; Q. sect. Protobalanus), Trigonobalanoideae and the extinct genus Eotrigonobalanus.Among the 18 fossil-species, six are described as new: Q. aimeeana, Q. casparyi, Q. multipilosa, E. campanulata,E. conwentzii, E. longianthera; and one new combination is published: Q. brachyandra (≡ Castanea brachyandra).In addition, a lectotype is designated for the name Quercites meyerianus and neotypes are designated for the namesCastanea inclusa and Quercus longistaminea (≡ C. longistaminea). Members of the Fagaceae probably inhabitedazonal and zonal vegetation types of the amber source area, including bottomland flood-plains and stream banks(Q. sect. Lobatae), dry habitats (Q. sect. Lobatae, Q. sect. Protobalanus), peaty soils, riparian and swamp forests(Castanopsis, Eotrigonobalanus), as well as mixed mesophytic forests (castaneoids, Quercoideae, trigonobalanoids).Affinities to extant North American and E to SE Asian floras support the recent notion that late Eocene Baltic amber(38 – 34 Ma) was formed in a warm-temperate climate
World Cynipoidea (Hymenoptera): A Key to Higher- Level Groups
No full textWhile much has been learned regarding the phylogeny and evolution of cynipoid wasps, clearly illustrated diagnostic tools and identification keys have remained stagnant. So too, where keys do exist, they are often to genus or species, and there are no user-friendly keys to groups such as tribes, subfamilies, or families. This state of affairs leaves a knowledge gap for non-specialists and slows future research on the group. To address this, we provide a fully illustrated key to the higher-level groups of world Cynipoidea. We also provide sum-maries of all higher-level taxa with updated generic lists, biological data, distribution, and literature resources. The dichotomous key presented here is complimented with a multi-entry matrix-based key, created in Lucid, and served on www.waspweb.org with online versions of the dichotomous keys also available
Det svenska nationella miljöövervakningsprogrammet för miljögifter i marin biota (fram till 2019 års data) - Temporal och spatial variation
No full textThe report summarises the monitoring activities within the National Swedish Contaminant Programme inmarine biota.Few trends are found for the biological variables of the biota included in the programme (age, weight,length, and fulton´s condition factor). This is expected, as samples are selectively selected to avoidtrends. However, all variables for Holmöarna in the Bothnian Bay and the fish age at the West Coastsites (Kullen, Fladen and Väderöarna) stands out for herring, cod and perch as having upward trendsover the last 10 years. Since many of the contaminants presented in this report bioaccumulate, this islikely to affect the trends presented below.For the aggregated herring data (on sub-basin scale) on chlorinated pesticides, PCBs, dioxins andfurans, brominated flame retardants and perfluorinated substances (PFAS) a general downward trendfor the last 10 years (2010-2019) is seen for all sub-basins (Southern and Northern Baltic Proper andBothnian Sea and Bay) except the West Coast. On the West Coast, changes are small and often nonsignificant.The contaminant concentrations are in general lowest on the West Coast but theconcentration difference between the West Coast and the other sub-basins has shrunken over the last10 years as the concentrations in the other sub-basins are decreasing towards West Coast levels. Theperfluorinated compound FOSA is an exception to this picture, with 2-4 times higher concentrations onthe West Coast compared to the Baltic Sea. For the metals, no common patterns are seen for theaggregated herring data across the metals or for each specific metal between sub-basins
Pre-extinction Demographic Stability and Genomic Signatures of Adaptation in the Woolly Rhinoceros
No full textAncient DNA has significantly improved our understanding of the evolution and population history of extinct megafauna. However, few studies have used complete ancient genomes to examine species responses to climate change prior to extinction. The woolly rhinoceros (Coelodonta antiquitatis) was a cold-adapted megaherbivore widely distributed across northern Eurasia during the Late Pleistocene and became extinct approximately 14 thousand years before present (ka BP). While humans and climate change have been proposed as potential causes of extinction [1-3], knowledge is limited on how the woolly rhinoceros was impacted by human arrival and climatic fluctuations [2]. Here, we use one complete nuclear genome and 14 mitogenomes to investigate the demographic history of woolly rhinoceros leading up to its extinction. Unlike other northern megafauna, the effective population size of woolly rhinoceros likely increased at 29.7 ka BP and subsequently remained stable until close to the species’ extinction. Analysis of the nuclear genome from a similar to 18.5-ka-old specimen did not indicate any increased inbreeding or reduced genetic diversity, suggesting that the population size remained steady for more than 13 ka following the arrival of humans [4]. The population contraction leading to extinction of the woolly rhinoceros may have thus been sudden and mostly driven by rapid warming in the Bolling-Allerod interstadial. Furthermore, we identify woolly rhinoceros-specific adaptations to arctic climate, similar to those of the woolly mammoth. This study highlights how species respond differently to climatic fluctuations and further illustrates the potential of palaeogenomics to study the evolutionary history of extinct species
Amber from the Triassic to Paleogene of Australia and New Zealand as exceptional preservation of poorly known terrestrial ecosystems
No full textThe Northern Hemisphere dominates our knowledge of Mesozoic and Cenozoic fossilized tree resin (amber) with few fndings from the high southern paleolatitudes of Southern Pangea and Southern Gondwana. Here we report new Pangean and Gondwana amber occurrences dating from ~230 to 40 Ma from Australia (Late Triassic and Paleogene of Tasmania; Late Cretaceous Gippsland Basin in Victoria; Paleocene and late middle Eocene of Victoria) and New Zealand (Late Cretaceous Chatham Islands). The Paleogene, richly fossiliferous deposits contain signifcant and diverse inclusions of arthropods, plants and fungi. These austral discoveries open six new windows to diferent but crucial intervals of the Mesozoic and early Cenozoic, providing the earliest occurrence(s) of some taxa in the modern fauna and flora giving new insights into the ecology and evolution of polar and subpolar terrestrial ecosystems.Tis publication represents aresearch output from Australian Research Council Discovery Grant ARC-DP140102515 (2014–2017) to J.S., D.B.and D.C., a Robert Blackwood Seed grant to J.S., and from Spanish AEI/FEDER, UE Grant CGL2017–84419 (theCRE project) to A.A. and E.P. Additional funds provided to C.M. for feldwork and preparation by the NationalGeographic Society (Grant 9761–15) and the Paleontological Society</p
Refined Permian-Triassic floristic timeline reveals early collapse and delayed recovery of south polar terrestrial ecosystems
No full textThe collapse of late Permian (Lopingian) Gondwanan floras, characterized by the extinction of glossopterid gymnosperms, heralded the end of one of the most enduring and extensive biomes in Earth’s history. The Sydney Basin, Australia, hosts a near continuous, age-constrained succession of high southern paleolatitude (∼65–75°S) terrestrial strata spanning the end-Permian extinction (EPE) interval. Sedimentological, stable carbon isotopic, palynological, and macrofloral data were collected from two cored coal-exploration wells and correlated. Six palynostratigraphic zones, supported by ordination analyses, were identified within the uppermost Permian to Lower Triassic succession, corresponding to discrete vegetation stages before, during, and after the EPE interval. Collapse of the glossopterid biome marked the onset of the terrestrial EPE and may have significantly predated the marine mass extinctions and conodont-defined Permian–Triassic Boundary. Apart from extinction of the dominant Permian plant taxa, the EPE was characterized by a reduction in primary productivity, and the immediate aftermath was marked by high abundances of opportunistic fungi, algae, and ferns. This transition is coeval with the onset of a gradual global decrease in δ13Corg and the primary extrusive phase of Siberian Traps Large Igneous Province magmatism. The dominant gymnosperm groups of the Gondwanan Mesozoic (peltasperms, conifers, and corystosperms) all appeared soon after the collapse but remained rare throughout the immediate post-EPE succession. Faltering recovery was due to a succession of rapid and severe climatic stressors until at least the late Early Triassic. Immediately prior to the Smithian–Spathian boundary (ca. 249 Ma), indices of increased weathering, thick redbeds, and abundant pleuromeian lycophytes likely signify marked climate change and intensification of the Gondwanan monsoon climate system. This is the first record of the Smithian–Spathian floral overturn event in high southern latitudes.This research was funded by collaborative research grants from the National Science Foundation (EAR-1636625 to CRF and TDF).</p
Dwelling in the dead zone—vertebrate burrows immediately succeeding the end-Permian extinction event in Australia
No full textA distinctive burrow form, Reniformichnus australis n. isp., is described from strata immediately overlying and transecting the end-Permian extinction (EPE) horizon in the Sydney Basin, eastern Australia. Although a unique excavator cannot be identified, these burrows were probably produced by small cynodonts based on comparisons with burrows elsewhere that contain body fossils of the tracemakers. The primary host strata are devoid of plant remains apart from wood and charcoal fragments, sparse fungal spores, and rare invertebrate traces indicative of a very simplified terrestrial ecosystem characterizing a ‘dead zone’ in the aftermath of the EPE. The high-paleolatitude (~ 65–75deg S) setting of the Sydney Basin, together with its higher paleoprecipitation levels and less favorable preservational potential, is reflected by a lower diversity of vertebrate fossil burrows and body fossils compared with coeval continental interior deposits of the mid-paleolatitude Karoo Basin, South Africa. Nevertheless, these burrows reveal the survivorship of small tetrapods in considerable numbers in the Sydney Basin immediately following the EPE. A fossorial lifestyle appears to have provided a selective advantage for tetrapods enduring the harsh environmental conditions that arose during the EPE. Moreover, high-paleolatitude and maritime settings may have provided important refugia for terrestrial vertebrates at a time of lethal temperatures at low-latitudes and aridification of continental interiors.The work was funded by a collaborative research grant from the National Science Foundation (EAR-1636625 to C.R.F. and T.D.F.)</p
Grey seal Halichoerus grypus recolonisation of the southern Baltic Sea, Danish Straits and Kattegat
No full textThe grey seal became locally extinct in the southern Baltic Sea, Danish Straits and Kattegat in the early 1900s after prolonged culling campaigns. Here, we combine national monitoring and anecdotal data from Denmark, Sweden, Germany and Poland to report on the grey seal's recolonisation of those areas and the initial reestablishment of breeding colonies. Grey seal occurrence has steadily increased since year 2003 as evidenced by the coordinated Baltic Sea moult censuses. At the first census in 2003, there were 146 grey seals along the southern Baltic coasts of Sweden and Denmark, ca 1% of the total Baltic Sea population count. Since 2015, this has increased to 2000–2600 grey seals, or ca 7% of the total population count. Since the local extinction, there have been sporadic breeding events in the 1940s on sea ice around Bornholm and in the 1980s and 1990s on haul-outs in Kattegat. In 2003, the first two pups in the southern Baltic Sea were recorded at Rødsand, Denmark. This is to date the only site in the southern Baltic Sea with regular annual pupping since the recolonisation. Since 2000, there have also been sporadic breeding events in Danish Kattegat, southern Sweden, Poland and Germany. At Rødsand, there have been at least 3–10 pups recorded every year since initiation of monitoring in 2011, with an increasing tendency until 2017 with 10 pups counted, which subsequently decreased to 5–6 pups annually in 2018–2020. Compared to recolonising events in the Atlantic, the numbers of pups are low. This may be caused by differences in population dynamics, recolonisation distances, habitat and mortality and effects of rehabilitation programmes. It is likely that the breeding distribution will spread throughout the southern Baltic, Danish Straits and Kattegat if appropriate protection measures of seals and haul-outs are installed