Swedish Museum of Natural History
Not a member yet
1516 research outputs found
Sort by
Graphic and statistical overview of temporaltrends and spatial variations in the SwedishNational Monitoring Programme forContaminants in Freshwater Biota (including data through 2023)
No full textFirst Iberian aspidothoracid megasecopteran insect and associated plants evidencing herbivory in a tropical Carboniferous forest from León, Spain
No full textWe describe Aspidothorax hispanicus sp. nov. from Gzhelian, Pennsylvanian strata of León, Spain, representing the first occurrence of Aspidothoracidae in the Iberian Peninsula. This discovery expands the paleogeographical range of the family, previously known only from the Russian Federation and France. The new insect is preserved in close association with foliar remains of medullosan (Alethopteris zeilleri) and callistophytalean (Pseudomariopteris cordato-ovata) seedferns whose environmental preferences suggest that the new insect species inhabited humid tropical forests. The fossil leaves bear six types of damage, probably produced by insects, belonging to three functional feeding groups: margin feeding, hole feeding, and piercing and sucking. This diversity of interactions highlights varied feeding strategies, including chewing, piercing and sucking behaviors, evidencing a more complex range of herbivory in the area than previously known. The stylet mouthparts of Megasecoptera make these insects strong candidates for producing the piercing and sucking damage on the associated plants. The presence of dark patches and spots on the fossil wing, probably represents a camouflage strategy against predators, such as Palaeodictyoptera and other active hunters. The dark wing apex might also reflect the presence of sexual dimorphism or courtship behavior. This new assemblage of insects, in addition to plants and plant-insect interactions, contributes to a broader paleoecological understanding of the Carboniferous forests of the La Magdalena Coalfield
Museomics unravels cryptic diversity in an endemic group of New Guinean songbirds
No full textDeciphering cryptic diversity can have substantial implications for ourunderstanding of evolutionary processes and species conservation. Birdsare arguably among the best studied organismal groups, but even in avianclades there are some genera that have not been thoroughly surveyed.This is particularly true for taxa that occur in hyperdiverse biogeographicregions. In this study, we focus on an endemic group of New Guineanbirds, the jewel-babblers (genus: Ptilorrhoa), and study the diversificationhistory of all known taxa. We assemble a de novo genome using linkedread sequencing and genomic data for 40 historical specimens. Bothphylogenomic and population-genomic analyses strongly support therecovery of a cryptic species and shed new light on the diversificationhistory of this group. The blue jewel-babbler (Ptilorrhoa caerulescens) is aparaphyletic species complex and P. c. nigricrissus is more closely relatedto the phenotypically distinct and sexually dimorphic P. geislerorum, thanto other P. caerulescens subspecies. These findings demonstrate that evenin well-studied groups such as birds, cryptic diversity can still be aprevalent reality. Moreover, by deciphering cryptic diversity, we shed newlight on the processes driving speciation within Ptilorrhoa and the need topotentially revise the taxonomic status of all subspecie
Exceptionally preserved epithelial cell–controlled organic templates in Cambrian chancelloriid sclerites
No full textThe first appearance of animal skeletons is one of the most significant events in the history of life. Knowledge of how early animals constructed their skeletons is generally poor, largely because taphonomic pathways obscure details of skeletal secretory mechanisms. Here, we report exceptionally preserved organic templates from the sclerites of chancelloriids, an enigmatic and widespread organism in the Cambrian. The organic templates form the mineralized layer of the sclerite and bear a striking resemblance, in both size and morphology, to the organic templates that control biomineralization in modern molluscs. Based on the similarities to modern molluscs, we postulate that the mineralized sclerites of chancelloriids were secreted entirely by epithelial cells within the organic template, reflecting a mechanism known to be used by a wide range of eumetazoans. This new awareness of chancelloriid microstructure provides further evidence that the close affinity between chancelloriids and poriferans should be rejected and that chancelloriids should be assigned to a eumetazoan clade
Jurassic system stratigraphy at the Kamianka village. Part 3. The Pidluzhna formation
No full textIntroduction. The paper is devoted to the study of the Pidluzhna Formation of the Jurassic system of the North-Western outskirts of the Donetsk folded structure and is a continuation of a series of publications highlighting the stratigraphy of Jurassic deposits in key areas near the town of Izyum and the village of Kamianka. Analysis of previous publications. The Pidluzhna Formation was first identified by L.F. Lungershausen in 1941, he noted the homogeneity of the lithological composition and the somewhat different nature of the sediments in the zones of relative uplift and subsidence. Later, these deposits were not considered in the rank of Formation, but were attributed to the Upper Bajoсian - Lower Bathonian. Material and methods. The Pidluzhna Formation is widespread in the Kamianskaya area. Since the deposits are composed mainly of clays, there are no more or less significant outcrops of it. The scientific search was based on the analysis of literature, results of previous drilling and mapping works, as well as own field, laboratory and analytical studies. Micropaleontological analysis and generalized data on the distribution of fossil remains were carried out. The palynological analysis of these deposits was also carried out, namely, stratified deposits with the help of microphytofossils. Results and discussion. Since the stratotype of the Pidluzhna Formation has not been precisely specified and currently the stratotype area is under urban development and only its small fragments are exposed, it is possible to propose as a neostratotype the outcrop of this Formation near the village of Sukha Kamyanka, in a ravine that extends north parallel to the Sukha Kamyanka - Yaremivka road. Lithology. The lithological composition of the Pidluzhna Formation was studied in detail by G.V. Karpova and V.G. Kosmachev. The main, clayey, part of the formation is composed of hydromicas with a slight admixture of montmorillonite group minerals and kaolin. Paleontological remains and Stratigraphy. This work summarizes previous paleontological data of scientists and supplements them with their own research. In general, these are brachiopods, cephalopods, gastropods, bivalves, malacostraca, ostracods, foraminifera, wood cuticles and tracheids, remains of prasinophyte and dinophyte algae, acritarchs, and spores and pollen of higher plants. Paleontological remains, including leading ammonite species, are found in the Pidluzhna Formation quite often. In the lower part of the Formation (Bajoсian) - the Garantiana garanti and Parkinsonia parkinsoni zones stand out, in the upper part (Bathonian) - lones of the Pseudocosmoceras michalskii. According to the data of palynological analysis, the conclusions regarding the age of the sediments of the Pidluzhna Formation are confirmed. A characteristic feature, namely the Bajoсian, is the dominance of fern-like Dictyophyllidites and the appearance of spores of Neoraistrickia rotundiformis, Duplexisporites anagrammensis, Converrucosisporites disparituberculatus, Laevigatosporites ovatus, Leptolepidites major, Densoisporites velatus and pollen of gymnosperms Callialasporites dampieri, Araucariacites australis, Vitreisporites pallidus. Foveosporites, Klukisporites, Lycopodiacidites and Uvaesporites, as well as fern-like Clathropteris obovata var. magna and the dominance of Concavisporites distinguishes the Bathonian deposits, which we observe in the Kamianka sections.Стаття присвячена дослідженню підлужної світи юрської системи Північно-Західної околиці Донецької складчастої споруди. Встановлений її речовинний склад та особливості його зміни по розрізу та по площі в межах околиць с. Кам’янка, щона південній Ізюмщині. Дослідження включало аналіз літературних даних та результатів картування, а також власні спостереження. Проведено палеонтологічний, в тому числі вперше детальний палінологічний аналізи, та узагальнені дані про поширення всіх викопних решток, що були встановлені в підлужній світі. В статті зведені всі попередні палеонтологічні дані науковців та доповнено власними дослідженнями. Загалом це – брахіоподи, головоногі молюски, черевоногі молюски, двостулкові молюски, малакостраки, остракоди, форамініфери, кутикули та трахеїди деревини, рештки празинофітових та динофітових водоростей, акритархи та спори і пилок вищих рослин. Підлужна світа, в межах дослідженої території, представленадосить одноманітними глинами. Глини гідрослюдисті з незначною домішкою монтморіллоніту та каоліну. Колір глин темносірий місцями з блакитним відтінком. Глини містять карбонатні (сидеритові та кальцитові) конкреції. Палеонтологічні залишки зустрічаються часто і по всьому розрізу світи. Представлені морськими групами, в тому числі важливими з точки зорустратиграфії. Встановлені зони за амонітами Garantiana garanti, Parkinsonia parkinsoni та лона Pseudocosmoceras michalskii,що дозволяє впевнено датувати відклади верхнім байосом – нижнім батом. Характерною ознакою байосу є домінування папоротеподібних Dictyophyllidites та поява Neoraistrickia rotundiformis, Duplexisporites anagrammensis, Converrucosisporitesdisparituberculatus, Laevigatosporites ovatus, Leptolepidites major, Densoisporites velatus та пилку голонасінних Callialasporitesdampieri, Araucariacites australis, Vitreisporites pallidus. Поява більшої кількості родів плавунів, вужачкових та ін. Foveosporites,Klukisporites, Lycopodiacidites та Uvaesporites, а також папоротеподібних Clathropteris obovata var. magna та домінуванняConcavisporites вирізняє батські відклади. Формування світи припадає на максимум середньо-пізньоюрської трансгресії з нормально морськими умовами накопичення осаду, продовжуються диференційовані тектонічні рухи локальних структур
Fundamental questions in meiofauna research highlight how small but ubiquitous animals can improve our understanding of Nature
No full textProperties of inflowing Pacific and Atlantic water govern total and methylated mercury profiles in the Arctic Ocean
No full textHigh methylmercury (MeHg) concentrations in Arctic marine biota have been linked to high MeHg uptake driven by shallow MeHg peaks at water depths of 100–300 m in the Arctic Ocean. To understand how the biogeochemical characteristics of each basin affects the distribution of total Hg (THg) and MeHg across the Arctic Ocean, the spatial patterns of THg and MeHg were investigated using data from new transects in the Beaufort Sea (BS) and previously published Arctic Ocean expeditions covering the Canada Basin and Makarov Basin in the Pacific sector, and Amundsen Basin and Nansen Basin in the Atlantic sector. In the BS, the THg concentration in the polar mixed water increased with salinity (r = 0.87, p < 0.01), which was linked to THg transport from the Chukchi Shelf. Transport of Hg from the Chukchi Shelf also drove elevated THg concentrations in the polar mixed water and halocline water in the Canada Basin and Makarov Basin compared to other Arctic basins. The MeHg concentration in the BS was positively correlated with the biological index in the Pacific summer water (r = 0.86, p < 0.01), demonstrating that intrusion of warm and nutrient-rich Pacific water promotes MeHg production in the BS. In line with this result, chlorophyll-a showed a comparable cross-basin trend to that of MeHg, with the highest values in the Nansen Basin. In the halocline water, MeHg concentrations were highest in the Canada Basin likely due to the largest availability of Hg(II). On the contrary, MeHg concentration was highest in the Nansen Basin in the Atlantic water layer, which could be related to the higher seawater temperature and enhanced biological production. The results of this study underscore the critical role of Pacific and Atlantic inflows in modulating the profiles of THg and MeHg in the Arctic Ocean
