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Digital endocasts from two late Eocene carnivores shed light on the evolution of the brain at the origin of Carnivora
No full textThe evolution of the brain at the origin of Carnivora remains poorly understood, largely owing to the limited number of cranial endocasts known from Carnivoramorpha and basal crown Carnivora. Here, we use x-ray computed tomography to create digital endocasts of two early carnivores, Quercygale angustidens and Gustafsonia cognita. Quercygale angustidens is generally regarded as the sister taxon to Carnivora and Nimravidae and is thus of great interest to further our understanding of the evolutionary changes that occurred at the origin of Carnivora. Gustafsonia cognita provides a comparison to a contemporary crown carnivoran. We describe the endocasts of these two taxa, placing them in the context of carnivoramorphan phylogeny. Both endocasts preserve the cerebellum in great detail, resulting in a better understanding of the morphology of this part of the brain in early carnivores. Gustafsonia cognita, despite its small size, geological age and basal position, displays a sulcal pattern typical of Amphicyonidae, reaffirming its position within the family. Nimravids; and early carnivorans, such as Gustafsonia cognita, Proailurus lemanensis and Hesperocyon gregarius, have more expanded neocortices than Quercygale angustidens. Current evidence suggests that the increase in gyrification in basal Carnivoramorpha occurred mainly through elongation of existing sulci and entered a new phase at the origin of crown Carnivora. Additional sulci appeared in early members of the order, resulting in distinctive sulcal patterns in the different carnivoran families. Nevertheless, more endocasts of basal carnivorans and carnivoramorphans are needed to better understand the processes driving the evolution of the brain in this group.This research was funded in part by the Swedish Research Council (VR). The authors would like to thank Tunhe Zhou at the Stockholm University Brain Imaging Centre (SUBIC) for assisting with the scanning of NRM-PZ M2329. Additionally, data acquisition was supported by a grant to the Stockholm University Brain Imaging Centre (SU FV-5.1.2-1035-15). We thank DigiMorph.org for scanning TMM 40209-200 and for making the scan data available online. The scanning of TMM 40209-200 was supported by NSF grant IIS-0208675. CT scan data of NRM-PZ M2329, as well as surface renderings of NRM-PZ M2329 and TMM 40209-200 and their respective endocasts are available on MorphoSource:NRM-PZ M2329 CT scan images: https://doi.org/10.17602/M2/M166156NRM-PZ M2329 surface rendering of fossil: https://doi.org/10.17602/M2/M343577NRM-PZ M2329 surface rendering of endocast: https://doi.org/10.17602/M2/M343580TMM 40209-200 surface rendering of fossil: https://doi.org/10.17602/M2/M355593TMM 40209-200 surface rendering of endocast: https://doi.org/10.17602/M2/M355598CT scan of the holotype of Gustafsonia cognita: TMM 40209-200, available on DigiMorph: http://www.digimorph.org/specimens/Miacis_cognitus/</p
Princivalleite, Na(Mn2Al)Al6(Si6O18)(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup from Veddasca Valley, Varese, Italy
No full textA Late Paleocene age for Greenland’s Hiawatha impact structure
No full textThe ~31-km-wide Hiawatha structure, located beneath Hiawatha Glacier in northwestern Greenland, has been proposed as an impact structure that may have formed after the Pleistocene inception of the Greenland Ice Sheet. To date the structure, we conducted 40Ar/39Ar analyses on glaciofluvial sand and U-Pb analyses on zircon separated from glaciofluvial pebbles of impact melt rock, all sampled immediately downstream of Hiawatha Glacier. Unshocked zircon in the impact melt rocks dates to ~1915 million years (Ma), consistent with felsic intrusions found in local bedrock. The 40Ar/39Ar data indicate Late Paleocene resetting and shocked zircon dates to 57.99 ± 0.54 Ma, which we interpret as the impact age. Consequently, the Hiawatha impact structure far predates Pleistocene glaciation and is unrelated to either the Paleocene-Eocene Thermal Maximum or flood basalt volcanism in east Greenland. However, it was contemporaneous with the Paleocene Carbon Isotope Maximum, although the impact’s exact paleoenvironmental and climatic significance awaits further investigation
Hälsa, sjukdomar och dödsorsaker hos marina däggdjur 2021. : Resultat från obduktion och provtagning av marina däggdjur som undersökts på SVA,
No full textHälsoundersökning av marina däggdju
A new lycophyte megaspore, Paxillitriletes permicus, from the upper Permian of Southwest China
No full textLycophytes were an important group of plants in the late Permian (Lopingian) vegetation of Southwest China. However, our understanding of these lycophytes is based mostly on the study of megafossil specimens. Here, we describe a unique lycophyte megaspore, Paxillitriletes permicus Sui, McLoughlin et Feng sp. nov., from the Lopingian Xuanwei Formation of Yunnan Province, Southwest China. This trilete megaspore is characterized by prominent membraneous triradiate flanges, long bifurcate spines, an arcuate ridge expanded into a zona, and triangular to polygonal reticulate sculpture. Ultrastructural analysis reveals that the megaspore wall consists of four layers. The innermost layer is the foot layer, which forms a thin and solid basal lamina. It is covered by a dense layer containing small and parallel sporopollenin grains. A thick spongy layer is developed exterior to the dense layer and consists of elongate, curved, and intersected sporopollenin units with porous zones. The outermost layer is dense, of variable thickness, and forms the processes. Morphological and ultrastructural features indicate that the new megaspore belongs to a herbaceous isoetalean. This is the first detailed investigation of megaspores from the Lopingian of China using scanning and transmission electron microscopy. Our discovery represents the oldest occurrence of Paxillitriletes, and adds to the diversity of late Permian lycophytes in the Cathaysian Flora in the paleotropics of the eastern Tethys Ocean.This study was jointly supportedby the Strategic Priority Research Program of Chinese Academy of Sciences (XDB26000000), the Second Tibetan Plateau Scientific Expedition and Research (2019QZKK0706), the Yunnan Provincial Science and Technology Department (2019FJ010), and the Key Research Program of the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS-201905). S.M. is funded by a grant from the Swedish Research Council (VR grant number 2018-04527).</p
Palaeobotanical collections and facilities at the Swedish Museum of Natural History
No full textThe Swedish Museum of Natural History (Naturhistoriska riksmuseet: NRM), under the authority of the Swedish Ministry of Culture, is the largest museum in Sweden in terms of research and collections. Although officially founded in 1819 by the Royal Swedish Academy of Sciences, some collections held at the museum date back to donations received by the academy following its foundation in 1739. The museum includes six research departments (Palaeobiology, Zoology, Botany, Geology, Bioinformatics, and Environmental Science) along with separate divisions for exhibitions and education. Palaeobotanical research is currently carried out within the Department of Palaeobiology (PAL). The department’s homepage can be found at: https://www.nrm.se/ en/forskningochsamlingar/paleobiologi.9000584.html. The department hosts about two million palaeontological specimens; around 400,000 of these are fossil plants, algae and fungi—making this one of the world’s largest palaeobotanical resources. The department currently hosts 24 palaeontologists, of which seven are full-time permanent employees (Vajda & Skovsted, 2021). The remainder are emeriti, students, postdoctoral researchers and additional researchers funded through scholarships, fellowships and other grants
Stable isotope analysis of carnivores from the Turkana Basin, Kenya: Evidence for temporally-mixed fossil assemblages
No full textStable isotope palaeoecology of fossil mammals is a key research tool for understanding the environmental context of hominin evolution in the Plio-Pleistocene of Africa. Well studied mammal groups include bovids, suids, equids, proboscideans and primates, but to date there has been no in-depth study of modern and fossil carnivores. Here we produce an Africa-wide oxygen and carbon enamel isotope dataset for modern carnivores and compare it with fossil carnivore data sampled from the Plio-Pleistocene Omo Group of the Turkana Basin, Kenya. Comparison of modern carnivore carbon isotopes with satellite images of land cover indicates that carnivore δ13C is related to the proportion of woody cover in the local environment. Modern carnivore oxygen isotopes are strongly influenced by the δ18O of meteoric water, through drinking from standing water and through prey body fluids. Carbon isotope data from fossil carnivores shows close agreement with palaeovegetation reconstructions from δ13C of palaeosol carbonates from the same geological Members, and a similar long-term trend in δ13C values through time (4 Ma to 1 Ma), reflecting a gradual increase in the proportion of C4 grasses in the Turkana Basin. This increase in the δ13C of large carnivores is consistent with the evidence from other mammalian groups for an increase in the proportion of grazers compared to browsers and mixed feeders during this time interval. Two distinct trends within oxygen versus carbon isotope space indicates that the fossil carnivores lived during two distinct climatic regimes – one in which palaeo-lake Turkana was freshwater, and one in which the lake resembled its modern-day hyperalkaline state. These two climatic states most likely represent the end-members of precessionally-driven rainfall extremes over the Ethiopian Highlands. This indicates that each studied faunal assemblage from the Omo Group is a time- and climate-averaged palimpsest; this has significant implications for the interpretation of environmental signals and community palaeoecology derived from Turkana Basin fossil mammals, including early hominins.PJH would like to thank the Palaeontological Association for financial support and Anne-Lise Jourdan for technical support at the University College London BEIF lab. TEC was supported by the US National Science Foundation (NSF-1740383) and the FH Brown Presidential Chair Fund. LW was supported by the Swedish Research Council (2015–04587). Logistical support of both the National Museums of Kenya and the Turkana Basin Institute is gratefully acknowledged by TEC, FKM, OM, and LNL. Laurence Frank and Bruce Patterson collected many of the modern carnivore specimens and those collections were accessioned by the National Museums of Kenya.</p
Causes of Death and Pathological Findings in Stranded Harbour Porpoises (Phocoena phocoena) from Swedish Waters
No full textConverting environmental quality standards for evaluation of fish contaminant monitoring data - tissue conversion factors for mercury, cadmium, lead and selected PFASs
No full textThe aim of the report is to produce improved estimates of tissue conversion factors (k) to use within environmental monitoring. The contaminant distribution across a range of marine and freshwater fish species from Northern Europe freshwater and the Baltic Sea was investigated. New tissue conversion factors were established and converted threshold limits (C-EQS or C-QS) for tissues of relevance for monitoring (liver and muscle) presented. We further explored inter-species variability in contaminant distribution, which can result in the need to create species-specific conversion factors. In this study, we use conversion factors that assumes a proportional relation between two tissue concentrations. We recommend that this method is always used when the aim is to convert between tissue concentrations for monitoring purposes. This will allow for better transparency and allow for easy comparison between studies, something that is made difficult at the moment due to the use of different alternative methods for conversion. Based on the analysis we recommend four new threshold value estimates that can be used within environmental monitoring of fish. For mercury (Hg) we only looked at the kmuscle/whole fish and did not consider liver measurements. We recommend the use of a C-EQSmuscle of 24 ng g-1 ww across all fish species. For cadmium (Cd) and lead (Pb) we calculated C-QSliver estimates based on conversion from both the QSmuscle-human health and QSwhole fish-sec pois. For Cd, we found significant differences between the two species investigated (herring and perch) as well as ten times higher C-QSliver based on the QSmuscle-human health than the QSwhole fish-sec pois. From a precautionary principle we recommend to use the herring specific k and the QS for secondary poising set for whole fish concentration to set the C-QSliver, which lead to a C-QSliver for Cd of 2.6 μg g-1 ww. For lead (Pb), the liver:muscle dataset was considered less robust than the liver:whole fish dataset. Also, for Pb significant differences were found between k’s in herring and perch. We recommend using a C-QSliver of 0.3 μg g-1 ww for Pb based on perch data. For PFOS we only looked at the kliver/muscle and did not consider whole fish measurements. We recommend the use of a C-EQSliver of 153 ng g-1 ww across all fish species despite some differences in k between the six species included in the estimate. For all contaminants, more data on additional fish species and data on the same species but better distributed between marine and freshwater environments (for species living in both like perch) is needed to elucidate the need for species specific and environment specific thresholds. In addition, more observations with concentrations close to the thresholds are needed for Cd and Pb to bring down the uncertainty on the QSliver estimates, which are currently, based on extrapolation of values more than a factor ten below the thresholds
