Swedish Museum of Natural History
Not a member yet
1516 research outputs found
Sort by
Early gigantic lamniform marks the onset of mega-body size in modern shark evolution
No full textLamniform sharks are amongst the largest-bodied extant fishes and have an evolutionary history spanning ~135 million years (Ma). Fossils correlate their initial development of mega-body size ( ≥6m)with ecological radiation as marine top-predators during the later part of the mid-Cretaceous (after the late Albian, ~100 Ma). Here, we push back this earliest appearance of gigantic lamniforms by ~15 Ma (upper Aptian, ~115 Ma) with the discovery of enormous cardabiodontid shark remains from northern Australia. We compiled a comprehensive dataset of vertebral centrum diameters versus maximum body length measurements for living lamniforms to calculate length and mass estimates of extinct taxa using both intraspecific and interspecific regression models. Our results show that mega-body size is an ancient lamniform trait, with the Australian cardabiodontid being around 6–8 m and over 3 tons. This rivalled some of the largest coeval marine reptiles and suggests that lamniforms invaded top-predator niches from an early stage in their adaptive evolution
Vertebral microstructure marks the emergence of pelagic ichthyosaurs soon after the End Permian Mass Extinction
No full textIchthyosaurs were the first fully marine tetrapods, and evolved a streamlined body, flippers, live birth, and endothermy-like physiology. However, the transition to these adaptations and how it relates to divergence into ocean environments is ambiguous. Here, we use vertebral bone microstructure to document the first ontogenetic series of two Early Triassic taxa that include the oldest ichthyosaur foetal fossils. One series is from Grippia, an early ichthyopterygian with a small body, and limbs with some plesiomorphic features. The other is a large, contemporaneous ichthyosaur, Cymbospondylus. Together, they phylogenetically bracket the ichthyopterygian-ichthyosaurian transition. Grippia has a unique microstructure with a distinctive compacted outer layer, whereas Cymbospondylus vertebrae are cancellous throughout, indicating a different ecology and swimming style. The dissimilar distribution of woven-parallel complex in the histology between the two taxa indicates that growth progressed at different speeds. We also document birth lines in ichthyosaurs for the first time. Pelagic, tail-propelled, rapid-growing ichthyosaurs were thus present less than five million years after the End Permian mass extinction, alongside more anguilliform ichthyopterygians. These data capture the ecological and evolutionary transition from reptiles with eel-like swimming to whale-like ichthyosaurs, implying a paradigm shift in ecology and physiology that paved the way for ichthyosaur radiation
Old collections, new taxa: late Carboniferous (Moscovian) roachoids (stem group Dictyoptera) among plants with insect interactions from the Benxi Formation, China, stored in European museums
No full textThe late Carboniferous (Pennsylvanian) witnessed the intensification of climatic gradients with the onset of the Late Paleozoic Ice Age. During this time, high latitudes were characterized by the spread of ice sheets, whereas the palaeotropics hosted the emergence of vast, verdant, coal-forming, swamp forests. Not only were the planet’s landscapes transformed through proliferation and diversification of vascular plants, but the evolution of diverse insect groups, including ‘primitive’ roachoids, reconfigured the terrestrial fauna. Here, we re-examine and describe new roachoid taxa from Moscovian strata of the Benxi Formation. The studied insect material was sourced from early 20th century collections held in the Swedish Museum of Natural History and the Royal Belgian Institute of Natural Sciences, and is co-preserved with a broad array of plant fossils—some with evidence of herbivory damage. Our findings introduce Tangshanblatta inexpectata gen. et sp. nov. (Phyloblattidae), Pseudaphtoromylacris paucinervis gen. et sp. nov. (in the family Pseudaphtoromylacridae, fam. nov.), Spilarchimylacris kaipingense sp. nov. (Archimylacridae), and Etomylacris straeleni sp. nov. and Sooblattella ater sp. nov. (both Mylacridae). We establish Pseudaphtoromylacridae on the basis of several new characters that clearly differentiate it from related families. Etomylacris is restored from synonymy with Mylacris. The co-preserved plant fossils reveal a rich palaeovegetation including pteridophytes, ‘pteridosperms’, sphenophytes, conifers, and arborescent lycophytes. The remains of these plants bear seven distinct damage types belonging to four functional feeding groups: hole feeding, margin feeding, piercing and sucking, and oviposition. This diversity of insects, plants, and herbivory strategies signifies a relatively complex food web in the Carboniferous tropical coal-forming forests of northeast China. This study also demonstrates the value of historical museum collections and the importance of inter-institutional collaboration for piecing together palaeobiodiversity and palaeoecological information from now inaccessible fossil sites
Earliest Jurassic plant assemblages from Sweden reveal a low-diversity ginkgoalean and cheirolepid flora dominating the post-extinction landscape
No full text• Background and Aims. Rich Triassic–Jurassic plant assemblages from Skåne, southern Sweden, have been documented extensively over the past two centuries. However, no macrofloras from the lowermost part of the Helsingborg Member (Lower Jurassic) have been forthcoming and thus the age of the successions has not been well constrained. Here we systematically describe and assess the palaeoecology and age of a newly discovered flora from the Boserup beds at Norra Albert Quarry, Skåne. • Methods. Plant macrofossils were examined using macrophotography, fluorescence microscopy and scanning electron microscopy. Palynological analysis of the strata hosting the macroflora contributed to the palaeoenvironmental interpretations and refined the age of the deposits. • Results. The low-diversity post-extinction recovery forests of the earliest Jurassic were dominated by ginkgoopsids, cheirolepid conifers and ferns, growing under seasonal mesothermal conditions. Dispersed charcoal indicates wildfires were present in the landscape at this time. • Conclusions. Despite the poor preservation of the fossils, the Boserup beds flora provides a window into vegetation recovery in the immediate aftermath of the end-Triassic extinction event. Initial recovery is characterized by the presence of needle- and scale-leafed seed plants (notably czekanowskialeans and Brachyphyllum species that produced Classopollis pollen), along with a range of ground ferns.This work was supported by the Knut & Alice Wallenbergs Stiftelse KAW (2020.0145 to V.V.) and Swedish Research Council VR grants (2017-05248 to G.N., 2019-4061 to V.V.and 2022-03920 to S.M.). The results are published with the permission of the Museum of Evolution, Uppsala University (PMU). The field works in the Norra Albert Quarry were supported from Uppsala University funds (2017–2019).</p
A new representative of the roachoid family Necymylacridae (stem group Dictyoptera) and associated vegetation with insect interactions from the Shanxi Formation (lower Permian), China
No full textA new roachoid species, Necymylacris sinica n. sp., is described from the lower Permian (Asselian, Cisuralian) Shanxi Formation in the Qinshui Basin, North China, based on a partially preserved forewing. This discovery represents the second record of the family Necymylacridae in China and the first from the Shanxi Formation in the Qinshui Basin. The holotype was found co-preserved with a low-diversity assemblage of 14 plant taxa (among 263 fossil-plant specimens), dominated by cordaitalean leaves (Cordaites principalis and Cordaites sp.) and pteridophytes (morphogenera Pecopteris spp.), with lesser proportions of sphenophytes, lycophytes, and seed ferns. The fossil flora and regional geological data suggest a warm, humid, low-diversity forest ecosystem in non-seasonal climates of palaeotropical Cathaysia. Evidence of plant-insect interactions, such as margin feeding, hole feeding, piercing and sucking, galling, oviposition, and seed predation, reveals that a diverse array of herbivorous insects with varying feeding strategies inhabited the Permian palaeoforest of the Qinshui Basin. These findings provide new information about the ecological complexity of early Permian palaeotropical forests during the peak of the Late Paleozoic Ice Age and new insights into the palaeoecology and biodiversity of Cathaysia during this period. The study underscores the importance of historical collections, such as those at the Swedish Museum of Natural History, in advancing our understanding of ancient ecosystems. Taxonomically, Stephanotermopsis rodendorfi Laurentiaux, 1966 is transferred into the family Necymylacridae
A High‐Throughput Ancient DNA Extraction Method for Large‐Scale Sample Screening
No full textLarge-scale DNA screening of palaeontological and archaeological collections remains a limiting and costly factor for ancient DNA studies. Several DNA extraction protocols are routinely used in ancient DNA laboratories and have even been automated on robotic platforms. Robots offer a solution for high-throughput screening but the costs, as well as necessity for trained technicians and engineers, can be prohibitive for some laboratories. Here, we present a high-throughput alternative to robot-based ancient DNA extraction using a 96-column plate. When compared to routine single MinElute columns, we retrieved highly similar endogenous DNA contents, an important metric in ancient DNA screening. Mitogenomes with a coverage depth greater than 0.1× could be generated and allowed for taxonomic assignment. However, average fragment lengths, DNA damage and library complexities significantly differed between methods but these differences became nonsignificant after modification of our library purification protocol. Our high-throughput extraction method allows generation of 96 extracts within approximately 4 hours of laboratory work while bringing the cost down by ~39% compared to using single columns. Additionally, we formally demonstrate that the addition of Tween-20 during the elution step results in higher complexity libraries, thereby enabling higher genome coverage for the same sequencing effort
Reference genome bias in light of species-specific chromosomal reorganization and translocations
No full textEvidence for deliberate burial of the dead by Homo naledi
No full textIn this study, we describe new results of excavations in the Dinaledi Subsystem of the Rising Star cave system, South Africa. In two areas within the Hill Antechamber and the Dinaledi Chamber, this work uncovered concentrations of abundant Homo naledi fossils including articulated, matrix-supported skeletal regions consistent with rapid covering by sediment prior to the decomposition of soft tissue. We additionally re-examine the spatial positioning of skeletal material and associated sediments within the Puzzle Box area, from which abundant H. naledi remains representing a minimum of six individuals were recovered in 2013 and 2014. Multiple lines of evidence exclude the hypothesis that skeletal remains from these three areas come from bodies that decomposed on the floor of the chamber or within a shallow depression prior to burial by sediments. The spatial positioning of skeletal material, the topography of the subsystem, and observations on sediments within and surrounding features exclude the hypothesis that rapid burial by sediment was a result of gravity-driven slumping or spontaneous movement of sediments. We present a minimal hypothesis of hominin cultural burial and test the evidence from all three areas, finding that this hypothesis is most compatible with the pattern of evidence. These results suggest that mortuary behavior, including cultural burial, was part of the repertoire of Homo naledi.Permits to conduct research in the Rising Star Cave system are provided by the South African Heritage Resource Agency (LRB). Permission to work in the Rising Star cave is given by the LRB Foundation for Research and Exploration. We would like to thank the University of the Witwatersrand’s Primate Fossil Access Committee for allowing access to the original material for study and the University Curator and Assistant Curator of Collections for assisting with logistics in studying the material. We would like to thank the Department of Diagnostic Radiology at the Charlotte Maxeke Academic Hospital for allowing access to their clinical CT scanner. We acknowledge the European Synchrotron Research Facility for providing access to facilities including the BM18 beamline. We would like to thank Matthew Caruana for discussions related to the stone object associated with the Hill Antechamber burial. We would like to thank the Spectrum Analytical Facility and the Department of Metallurgy at the University of Johannesburg for the analytical work on the sediments. Christian Reinke is specifically thanked for carrying out the XRF measurements (TM). The authors would like to acknowledge the funders of the various expeditions that recovered the fossil material and information, including 3d scanning and the production of AVR material described in this paper including the National Geographic Society (LRB, CJ, KB), the Lyda Hill Foundation (LRB) and the National Research Foundation of South Africa (LRB). Laboratory work, field work and travel was funded by the National Geographic Society (LRB, ME, AK, CJ, KB), the Lyda Hill Foundation (LRB, ME, AK) the Centre for Excellence in PalaeoSciences at the University of the Witwatersrand (now GENUS) (AK), the Fulbright Scholar Program (JH), John Templeton Foundation (LRB, JH) and National Research Foundation of South Africa (TM), University of Johannesburg Research Council (TM), and the Spectrum Analytical Facility at University of Johannesburg (TM).</p
Origin and evolution of the Variscan Léon eclogites: insights from zircon and garnet petrochronology
No full textEclogites record the deep burial and exhumation of crustal terranes, which are key tectonic markers in the evolution of orogenic belts. Unraveling the evolution of eclogites and eclogite-bearing terranes may nevertheless be challenging, especially in old and poly-tectonic orogens such as the Variscan orogen, where these are scarce and potentially reworked. The eclogite-bearing Léon Domain (Armorican Massif, France) is one such occurrence. The Léon Domain is situated at the crossing of several (micro)continents and has long been recognized as a potential recorder for the assembly of this part of the Variscan orogen. The origin and metamorphic history of these eclogites remains nevertheless largely unconstrained. In this study, samples of the Léon eclogite were subjected to garnet and zircon petrochronology. In situ U-Pb ages from zircon cores constrain the protolith age at 385.7±2.9 Ma (concordia age, mean square weighted deviate (MSWD) = 8.7 and corresponding weighted mean age at 385.7±1.6 Ma, MSWD = 1.14), which is similar to zircon U-Pb ages reported from enclosing orthogneisses. Low δ18O values (median at 4.32 ‰) from these cores indicate interaction with surface fluids during magmatic crystallization. Garnet growth in the eclogites, as constrained by Lu-Hf geochronology, occurred at 346.5±0.8 Ma (MSWD = 0.6; Fe-Ti-rich eclogite) and 349.1±1.6 Ma (MSWD = 0.3; kyanite-bearing eclogite). Pseudosection modeling, Zr-in-rutile thermometry, and major- and trace-element maps in garnet were used to constrain the garnet growth history close to the metamorphic peak from 740 °C at 2.15 GPa to 760 °C at 2.5 GPa. Zircon separates from a cross-cutting felsic intrusion provided 321.6±2.7 Ma (MSWD = 0.76), which is taken to constrain the age of deformation and migmatization during exhumation. The new results are inconsistent with the presence of a major suture in the Léon Domain; they instead indicate that the eclogite derives from a small and short-lived back-arc basin, in which large bodies of felsic magma (enclosing orthogneiss) and smaller basaltic intrusions (the eclogite protolith) were emplaced and allowed to interact with meteoric water. The Léon Domain records rapid, cyclic inversion of this basin and thus may serve as an ancient analogue to the evolution of the Central Neotethys system, where short-lived alternating pulses of crustal extension and compression correlate with episodes of trench retreat and advance. The new tectonic interpretation for the Léon Domain supports a strong control of the slab dynamics within the frame of the protracted subduction history of the Rheic paleo-ocean
