Swedish Museum of Natural History
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Fossil evidence unveils an early Cambrian origin for Bryozoa
No full textBryozoans (also known as ectoprocts or moss animals) are aquatic, dominantly sessile, filter-feeding lophophorates that construct an organic or calcareous modular colonial (clonal) exoskeleton. The presence of six major orders of bryozoans with advanced polymorphisms in lower Ordovician rocks strongly suggests a Cambrian origin for the largest and most diverse lophophorate phylum. However, a lack of convincing bryozoan fossils from the Cambrian period has hampered resolution of the true origins and character assembly of the earliest members of the group. Here we interpret the millimetric, erect, bilaminate, secondarily phosphatized fossil Protomelission gatehousei from the early Cambrian of Australia and South China as a potential stem-group bryozoan. The monomorphic zooid capsules, modular construction, organic composition and simple linear budding growth geometry represent a mixture of organic Gymnolaemata and biomineralized Stenolaemata character traits, with phylogenetic analyses identifying P. gatehousei as a stem-group bryozoan. This aligns the origin of phylum Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing back its first occurrence by approximately 35 million years. It also reconciles the fossil record with molecular clock estimations of an early Cambrian origination and subsequent Ordovician radiation of Bryozoa following the acquisition of a carbonate skeleton
Advances in Swedish palaeontology; the importance of fossils in natural history collections - The Department of Palaeobiology at the Swedish Museum of Natural History
No full textThis special issue aims to highlight the value of historical paleontological collections at museums in general, and at Swedish Museum of Natural History (NRM) in particular, providing a glimpse into our national fossil archives in the light of modern science and technology. Museums worldwide house fossil material collected over a time span of hundreds of years, in many cases from sedimentary successions that are no longer accessible. The paleontological collections at the NRM comprise over two million specimens that were contributed to the museum over the past 200 years, by pioneers, such as Nordenskiöld, Angelin, Holm, Stensiö, Nathorst, Halle and Lundblad. In more recent times, donations from other institutes and private persons have enriched our collections and a new generation of scientists and curators are continuously adding valuable material. For the purpose of this special issue, we focus mainly on our Swedish collections, focusing on scientifically important specimens not described previously, but also new material investigated with the latest technologies. Research highlighted in this issue covers most of the Phanerozoic eon incorporating macro- and microfossil data from marine and continental successions. We wish to show the reader that the collections represent an invaluable national resource and a great asset for both Swedish and international researchers long into the future
Camenellan tommotiids from the Cambrian Series 2 of East Antarctica: biostratigraphy, palaeobiogeography, and systematics
No full textCambrian Series 2 shelly fossils from thick carbonate successions in East Antarctica have received limited systematic treatment through the 20th century. Described here are the East Antarctic camenellan tommotiids from the Shackleton Limestone in the Central Transantarctic Mountains and the Schneider Hills limestone in the Argentina Range. This material comes from both newly sampled collections and incompletely described material from older collections. The assemblage supports correlation to the Dailyatia odyssei Zone and Pararaia janeae Trilobite Zone of South Australia, with the newly examined specimens of Dailyatia decobruta from the Shackleton Limestone providing direct correlation to the Mernmerna Formation of the Ikara-Flinders Ranges and White Point Conglomerate of Kangaroo Island. These East Antarctic assemblages include five species referred to Dailyatia, in addition to an undetermined kennardiid species and fragments of the problematic Shetlandia multiplicata. The results further corroborate the notion that fossiliferous carbonate clasts found on King George Island were sourced from the same carbonate shelf as the Shackleton Limestone, with the taxon S. multiplicata found in both units. The Schneider Hills limestone in the Argentina Range has yielded sclerites of Dailyatia icari sp. nov., currently only known from this location. The fieldwork in Antarctica was supported by operational support for polarresearch (RFI Polar VR 2010-6176) and the Swedish Polar Secretariatin collaboration with the United States Antarctic Program and USNational Science Foundation (NSF). Glenn A. Brock was supported inAntarctica by the Trans-Antarctic Association.</p
Trace fossils, algae, invertebrate remains and new U-Pb detrital zircon geochronology from the lower Cambrian Torneträsk Formation, northern Sweden
No full textNineteen ichnotaxa, together with algal and invertebrate remains, and various pseudo-traces and sedimentary structures are described from the Torneträsk Formation exposed near Lake Torneträsk, Lapland, Sweden, representing a marked increase in the diversity of biotic traces recorded from this unit. The “lower siltstone” interval of the Torneträsk Formation contains mostly simple pascichnia, fodinichnia and domichnia burrows and trails of low-energy shoreface to intertidal settings. The assemblage has very few forms characteristic of high-energy, soft-sediment, foreshore or upper shoreface environments (representative of the Skolithos ichnofacies). Uranium-lead (U-Pb) LA-ICPMS analysis of zircon from a thin claystone layer within the “lower siltstone” interval yielded a maximum depositional age of 584 ± 13 Ma, mid-Ediacaran. Most of the zircon is represented by rounded detrital grains that yield dates between 3.3 and 1.0 Ga. Although the age of the basal sandstone-dominated interval of the Torneträsk Formation remains elusive owing to the absence of fossils, the ichnofossil suite from the overlying “lower siltstone” interval lacks deep arthropod trackways, such as Rusophycus and Cruziana, and is suggestive of a very early (Terreneuvian, possibly Fortunian) Cambrian age. The ichnofauna is otherwise similar to early Cambrian trace fossil assemblages from other parts of Baltica, regions further south in modern Europe, and from Greenland
Neutron tomography, fluorescence and transmitted light microscopy reveal new insect damage, fungi and plant organ associations in the Late Cretaceous floras of Sweden
No full textNeutron tomographic reconstructions, macrophotography, transmitted light microscopy and fluorescence microscopy are employed to assess the quality of organic preservation, determine organ associations,identify insect damage, and document fungal interactions with selected Santonian–lower Campanian plant fossils from the northern Kristianstad Basin, southern Sweden. Fricia nathorstii (Conwentz) comb. nov., is proposed for a composite fossil comprising an anatomically preserved (permineralized) cupressacean conifer cone and its subtending, concealed, leafy axis (preserved asa mould) in the Ryedal Sandstone. Several other impressions of conifer and angiosperm leaf-bearing axes and isolated leaves are described under open nomenclature. Three cuticle types are described from the non-marine plant-bearing beds in the basal part of the succession exposed at Åsen, but these are only assigned to informal morphotypes pending a comprehensive review of the extensive fossil cuticle flora. Two species of ascomycote epiphyllous fungi from Åsen are established: Stomiopeltites ivoeensis sp. nov. (Micropeltidales) and Meliolinites scanicus sp. nov. (Meliolales). The latter provides an important calibration point for dating the divergence of Meliolales, being the first pre-Cenozoic representative of the order. Various additional fungal remains, including thyriothecia, scolecospores, chlamydospores, putative germlings, and hyphae, are described from the cuticular surfaces of conifer and angiosperm leaves from Åsen. Insect herbivory is expressed in the form of both margin-feeding and piercing-and-sucking damage on angiosperm leaves. The Santonian–early Campanian vegetation is inferred to have grown in strongly humid, mid-latitude, coastal plain settings based on the depositional context of the assemblages, leaf morphology, and the pervasive distribution of epiphyllous fungi.The stay of ATH in Stockholm was financed by the European Union’s Seventh Framework Programme (FP7/2007–2013) under grant agreement No. 226506 (SYNTHESYS). The authors acknowledge the support of ANSTO grant P5521 to CM.</p
Arthropod interactions with the Permian Glossopteris flora
No full textAn extensive survey of literature on the Permian floras of Gondwana reveals over 500 discrete arthropod–herbivory–damage/plant–taxon/stratigraphic–unit associations spanning all regions of the supercontinent from the earliest Asselian to the latest Changhsingian. Margin– and apex–feeding damage is the most common style of herbivory but hole– and surface–feeding, galling, and oviposition damage are locally well represented. Evidence for skeletonization and mucivory is sparse and that for leaf mining is equivocal. Wood and root boring is recognized widely but only where depositional conditions were conducive to the permineralization of plant axes. Wood boring and detritivory may have been especially favoured arthropod feeding strategies in Permian high latitudes where living foliage was scarce during the polar winters. Herbivory damage is most strongly apparent on glossopterid remains; other groups of broad–leafed gymnosperms and sphenopsids host moderate levels of damage. Damage features are under–represented on lycophytes, ferns and spine– and scale–leafed conifers. A survey of insect body fossils from the Gondwanan Permian reveals that most records are from a small number of rich assemblages that are dominated by Blattodea,Hemiptera, Grylloblattida, Mecoptera and Protelytroptera, accompanied by significant representations of Coleoptera, Glosselytrodea, Miomoptera, Neuroptera, Odonata, Protorthoptera, Palaeodictyopteroida, Paoliida, Paraplecoptera, Plecoptera, Psocoptera, Thysanoptera and Trichoptera, which collectively adopted a broad range of feeding styles. Oribatid mites and collembolans appear to have been important components of the wood–boring and detritivorous communities. Although temporal trends in herbivory styles and diversity are difficult to resolve from mostly incidental observations and illustrations of plant damage across Gondwana, the results of this study provide a baseline of qualitative data for future studies that should adopt a quantitative approach to the analysis of herbivory, spanning the shift from icehouse to hothouse conditions through the Permian of the Southern Hemisphere.Also funded by the National Research Foundation of South Africa (AfricanOrigins Platform, UID: 117685 to R.P.) and the DSI–NRFCentre of Excellence in Palaeontology (COE2018–18OPto R.P.)</p
Geochemical Fingerprints of Ginkgoales Across the Triassic-Jurassic Boundary of Greenland
No full textPremise of research. Geochemical fingerprinting of fossil plants is a relatively new research field complementing morphological analyses and providing information for paleoenvironmental interpretations. Ginkgoales contains a single extant species but was diverse through the Mesozoic and is an excellent target for biochemical analyses. Methodology. Cuticles derived from fresh and fallen autumn leaves of extant Ginkgo biloba and seven fossil gink- goalean leaf taxa, one seed fern taxon, and two taxa with bennettitalean affinity were analyzed by infrared (IR) microspec- troscopy at the D7 beamline in the MAX IV synchrotron laboratory, Sweden. The fossil material derives from Triassic and Jurassic successions of Greenland. Spectral data sets were compared and evaluated by hierarchical cluster analysis (HCA) and principal component analysis performed on vector-normalized, first-derivative IR absorption spectra. Pivotal results. The IR absorption spectra of the fossil leaves all reveal signatures that clearly indicate the pres- ence of organic compounds. Spectra of the extant G. biloba leaves reveal the presence of aliphatic chains, aromatic and ester carbonyl functional groups from polymer cutin and other waxy compounds, and polysaccharides. Inter- estingly, both the extant autumn leaves and the fossil specimens reveal the presence of carboxyl/ketone molecules, suggesting that chemical alterations during the initial stages of decomposition are preserved through fossilization. Two major subclusters were identified through HCA of the fossil spectra. Conclusions. Consistent chemical IR signatures, specific for each fossil taxon are present in cuticles, and suf- ficient molecular content is preserved in key regions to reflect the plants’ original chemical signatures. The alter- ations of the organic compounds are initiated as soon as the leaves are shed, with loss of proteins and increased ester and carboxyl/ketone compound production in the fallen leaves. We further show that the groupings of taxa reflect a combination of phylogeny and environmental conditions related to the end-Triassic event.Also funded by a Utrecht NetworkYoung Researchers grant to M. Pucetaite</p
The first Cretaceous megaspores from Ukraine
No full textThe first megaspores recovered from Ukrainian Lower Cretaceous strata are described and illustrated by reflected light and scanning electron micrography. Four lycopsid megaspore taxa are identified in core samples from north of Kherson (Khersons'ka Oblast), in the Black Sea Basin, southern Ukraine. Miospore assemblages recovered from the same samples reveal a slightly higher diversity of lycopsid microspores and, in conjunction with previous foraminiferal biostratigraphy, indicate an Aptian-Albian age for the strata. The megaspore suite shares genera with mid-Mesozoic assemblages from widely distributed parts of the world, but most of the Ukrainian specimens have subtle morphological differences from congeneric forms established in other regions. The megaspores accumulated in fluvial floodplain facies and highlight the potential of this region for investigating other Cretaceous mesofossils including early flowers
The response of zircon to the extreme pressures and temperatures of a lightning strike
No full textHypervelocity impacts can produce features in zircon that are not normally produced by endogenic processes. However, lightning can also induce extreme pressure–temperature excursions, and itsefect on zircon has not been studied. With the aim to recognise features that form in response to extreme pressure–temperature excursions but are not unique to hypervelocity impacts, we imaged and undertook microstructural characterization of zircon in a fulgurite (a tubular body of glass andfused clasts that formed in response to a lightning strike). We document zircon with granular ZrO2 and rims of vermicular ZrO2, features which vary in abundance with increasing distance from the fulgurite’s central void. This indicates that these features formed in response to the lightning strike. Zircon dissociation to ZrO2 and SiO2 is a high-temperature, relatively low-pressure phenomenon, consistent with previous suggestions that lightning strikes involve extreme temperatures as well as pressures greater than those usually generated in Earth’s crust but rarely > 10 GPa. The rims of monoclinic ZrO2 record crystallographic evidence for precursor cubic ZrO2, demonstrating that cubic ZrO2 is not unique to hypervelocity impacts. Given the likelihood that this fulgurite experienced pressures of, at most, a few GPa, evidence for cubic ZrO2 indicates peak temperatures > 2000 °C
Identifying the true number of specimens of the extinct blue antelope (Hippotragus leucophaeus)
No full textNative to southern Africa, the blue antelope (Hippotragus leucophaeus) is the only large African mammal species known to have become extinct in historical times. However, it was poorly documented prior to its extinction ~ 1800 AD, and many of the small number of museum specimens attributed to it are taxonomically contentious. This places limitations on our understanding of its morphology, ecology, and the mechanisms responsible for its demise. We retrieved genetic information from ten of the sixteen putative blue antelope museum specimens using both shotgun sequencing and mitochondrial genome target capture in an attempt to resolve the uncertainty surrounding the identification of these specimens. We found that only four of the ten investigated specimens, and not a single skull, represent the blue antelope. This indicates that the true number of historical museum specimens of the blue antelope is even smaller than previously thought, and therefore hardly any reference material is available for morphometric, comparative and genetic studies. Our study highlights how genetics can be used to identify rare species in natural history collections where other methods may fail or when records are scarce. Additionally, we present an improved mitochondrial reference genome for the blue antelope as well as one complete and two partial mitochondrial genomes. A first analysis of these mitochondrial genomes indicates low levels of maternal genetic diversity in the ‘museum population’, possibly confirming previous results that blue antelope population size was already low at the time of the European colonization of South Africa