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Trigonotarbids “hidden” in plant debris from a Late Pennsylvanian tropical forest at El Bierzo, Castilla y León Spain
No full textTwo new fossils belonging to the extinct arachnid order Trigonotarbida are described from uppermost Carboniferous (Gzhelian, Upper Pennsylvanian) strata of the Villablino and El Bierzo basins (Castilla y León; NW Spain). These discoveries represent the second and third Spanish records of this arachnid order and are among the oldest arachnid records known from the Iberian Peninsula. They also represent the first evidence of arachnids from the Villablino and El Bierzo basins. One fossil consists of an almost complete individual including the prosoma, opisthosoma, legs and pedipalps but its preservation in ventral view makes unequivocal identification difficult. Comparison with other material favours its assignment to Aphantomartus sp. (Aphantomartidae). The second specimen consists of a prosoma and opisthosoma preserved in dorsal view and is assigned to Aphantomartus areolatus. These two arachnids were preserved alongside several plant remains referable to ferns (Polymorphopteris polymorpha, Polymorphopteris integra, Nemejcopteris feminaeformis and Oligocarpia leptophylla), seed-ferns (Neuropteris ovata) and lycophytes (Cyperites bicarinatus). The abundance and diversity of co-occurring plant remains are consistent with the other known Spanish Aphantomartus record, which is also preserved in association with several plant fossils. Based on the new occurrences, we infer that Aphantomartus favoured humid, broad-leafed, evergreen forest habitats that provided a diverse array of food and shelter.This research also represents a contribution to the Médulas-Teleno UNESCO Global Geopark project. Artai Santos was supported by a postdoctoral fellowship from UNAM-DGAPA 2023–2024 and a subsequent postdoctoral fellowship funded from the Swedish Research Council Grant VR 2022-03920 to Stephen McLoughlin.</p
The fate of an old Mn–Fe amphibole species: Description of clino-ferro-suenoite, □Mn2Fe2+5Si8O22(Oh)2
No full textAbstract. Clino-ferro-suenoite, with the ideal formula □Mn2Fe2+5Si8O22(OH)2, previously named “dannemorite” or “manganogrunerite”, is formally recognized as a monoclinic member of the amphibole supergroup (IMA-CNMMC 2024-032). It occurs in iron-manganese skarn from the Hilläng mines, Dalarna, Sweden, associated with fayalite, spessartine, ferro-actinolite, calcite, magnetite and pyrite. It formed by partial replacement of manganoan fayalite during retrograde metamorphism. Individual crystals, up to 0.5 mm in length, are subhedral with a pale greenish yellow colour. The mineral is non-pleochroic and optically biaxial (–), with α = 1.670(5), β = 1.690(5), γ = 1.705(5); orientation Y || b, Z ⋀ c = 14(1)°. Cleavage parallel {110} and {010} is perfect and good, respectively. The Mohs hardness is about 6 and the mean Vickers hardness number was established as 872. The calculated density value is 3.46(1) g·cm-3. The crystal-chemical formula of clino-ferro-suenoite is A□B(Mn2+0.95Fe2+0.88Ca0.15Na0.01)Σ1.99 C(Fe2+3.57Mg1.38 Mn2+0.03Zn0.01Al0.01)Σ5.00 TSi8.00O22 W[(OH)1.99F0.01]Σ2.00, based on microprobe analyses, spectroscopic data (Mössbauer, infra-red, Raman) and a single-crystal X-ray diffraction study. Infra-red bands originating from O-H vibration modes appear at 3608, 3620, 3638, 3653 and 3668 cm-1, with the first and last one having weak intensities. The seven strongest reflections in the X-ray powder pattern [d values (in Å), Irel, (hkl)] are: 8.33, 100, (110); 3.278, 21, (240); 3.084, 72, (310); 2.784, 18, (330); 2.512, 19, (20-2); 1.526, 16, (0.12.0); 1.412, 19, (66-1). Unit-cell parameters obtained from single-crystal diffraction data (MoKα) are a = 9.59840(10), b = 18.3179(2), c = 5.33450(10) Å, β = 102.1630(10)° and V = 916.87(2) Å3 for Z = 2. Refinement of the crystal structure in the space group C2/m yielded R = 2.25% for 1379 reflections with Io > 2σ(I). Mg ions show preference for the octahedrally coordinated C sites in the order M(2) > M(1) > M(3)
A new ecomorph of Nimravidae, and the early macrocarnivorous niche exploration in Carnivora
No full textHere, we describe a new ecomorph of Nimravidae, Taotienimravus songi gen. et sp. nov., from the middle Oligocene of eastern Asia. Phylogenetic analyses indicate that the new species is closely related to Nimravus and Dinaelurus, and it represents a non-sabertooth ecomorph form with initial bone-cracking adaptation—a unique form among Nimravidae. An increase in body size among Nimravidae appears to have coincided with the demise of Oxyaenidae, another carnivorous clade in the Palaeogene. The initial emergence of macrocarnivorous adaptation of Carnivora by a felid-like ecomorph probably reflects competition dynamics. Nimravidae successfully occupied several ecological niches that were not exploited by Felidae, probably owing to the lack of competition within Carnivora during much of their evolutionary history. Our study underscores the role of both abiotic and biotic factors in shaping niche availability for these animals, emphasizing the need for discussions on niche change and evolution to be grounded in these considerations.This work was supported by the National Key Research and Development Program of China (no. 2023YFF0804501), National Natural Science Foundation of China (grant nos. 42572007, 42430207 and 42102001), China Scholarship Council, National Science Foundation, NSF grant DEB-1257572 to C.G.; PI : John J. Flynn, American Museum of Natural History, NY, an AMNH Frick Postdoctoral Fellowship (to C.G.) and the University of Poitiers.</p
Early Cretaceous vegetation in a polar ecosystem—Palynology and zircon dating of the Koonwarra Fossil Bed, Victoria, Australia
No full textThe Early Cretaceous Koonwarra site, Victoria, Australia, comprises a fossil bed considered to be a Konservat Lagerstätte famous for its myriad of fossil fish, feathers, invertebrates, and plants. Here we provide a vegetation reconstruction based on detailed palynology from a 21 m long drill core of which the basal 10 m represents the Koonwarra Fossil Bed (KFB) proper. Palynological analysis of the KFB revealed well-preserved assemblages, and c. 30,000 palynomorphs were identified, representing 138 taxa. The palynoassemblages are dominated by gymnosperm pollen, especially Alisporites (‘seed-ferns’), Araucariacites (Araucariaceae), Podocarpidites (Podocarpaceae) and monosulcate grain producers (most possibly Ginkgoales and Pentoxylales). Minor constituents include Eucommidiites and various arborescent gymnosperm pollen, including those produced by Cheirolepidiaceae such as Classopollis. The next most abundant groups are the fern spores, followed by lycophyte spores, both of which constitute a substantial portion of the palynoflora. Angiosperm pollen represents a minor but important element of the flora throughout the succession (1–6%). The LAICP-MS U–Pb dating of detrital zircon grains bracketing the Koonwarra Fossil Bed reveal a maximum dominant age of ≤ 114.1 Ma (latest Aptian) but with a few younger grains dated at 110 Ma.The palynological analysis tentatively ascribes a slightly younger age to the Unit, with assemblages referred to the very base of the Coptospora paradoxa Zone, signifying an early Albian age, based on the presence of the indices Coptospora paradoxa and Stoverisporites lunaris, combined with abundance data of various groups. Comparisons with coeval successions from other Southern Hemisphere localities, indicated that the Koonwarra assemblages derived from a cool temperate lake-margin vegetation
Frequent Hybridisation Between Parapatric Lekking Bird‐of‐Paradise Species
No full textHybridisation is known to occur between a wide range of taxa, including species for which strong sexual selection has led to markedly different sexual phenotypes and lek-mating behaviours. To what extent occasional hybridisation can overcome the reproductive barriers in such systems and, for example, lead to the establishment of hybrid zones is poorly known. In this study, we address this question by focusing on one of the most well-known avian radiations in which sexual selection has resulted in an extraordinary assemblage of phenotypic diversity and lek-mating behaviours: the birds-of-paradise (Paradisaeidae). We quantify the genome-wide distribution of introgression and find multiple signals of recent and historical gene flow between and within two genera of birds-of-paradise, Astrapia and Paradigalla. In addition, we present the first empirical genomic indication of a putative hybrid zone between two lekking bird-of-paradise species that differ substantially in their sexually selected traits and behaviours. Our findings are consistent with the idea that behavioural and phenotypic traits may constitute weaker pre- and post-zygotic barriers to gene flow than generally thought in lek-mating species
Geographical variation in mitogenomes of the largetooth sawfish Pristis pristis: Challenges and perspectives for conservation efforts
No full textNo evidence of transposable element bursts in the Galápagos Scalesia adaptive radiation despite hybridization, diversification and ecological niche shifts
No full textSymbiotic interactions on middle Cambrian echinoderms reveal the oldest parasitism on deuterostomes
No full textBiotic interactions are considered as major drivers of evolutionary changes, but their identification in the fossil record is extremely rare and controversial. Based on qualitative and quantitative analyses, we report evidence of a biotic interaction between an echinoderm host and its symbiont, probably a parasitic epibiont, from the Cambrian Wuliuan Stage of Australia. The echinoderm plates bear external outgrowths with a median pit at their distal end. These unusual structures have not been previously documented from Cambrian echinoderms and their lack of consistency across various morphological parameters, supports the interpretation that a biotic interaction generated these unique structures. Perturbations in plate microstructure and the overproduction of skeletal material in specific regions, together with reduced size, negatively impact the host’s growth suggesting a parasitic interaction. This reaction by the echinoderm host may represent the progressive embedment of the invasive epibiont. This record represents the oldest evidence of parasitism among deuterostomes.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101005611 for Transnational Access conducted at Ghent University. The Ghent University Special Research Fund (BOF-UGent) is acknowledged to support the UGent Core facility UGCT (BOF/COR/2022/008). K.D.B. was supported by the I.3.4 Action of the Excellence Initiative - Research University Programme at the University of Warsaw (Project: PARADIVE). Financial support from Vetenskraprådet (VR- 2021-04295) and National Science Foundation of China (42072003) is acknowledged</p
Preservation potential of Cambrian small shelly fossils in different microfacies, North China
No full textSmall shelly fossils (SSFs) have long been recognized as important to the studies of both metazoan evolution and the onset of biomineralization during the Cambrian radiation. The marked decline in the occurrence, diversity and abundance of SSFs in the middle to late Cambrian, when compared with the early Cambrian, has often been regarded as a result of the closure of a phosphatization window. Despite this, there have been numerous and consistent reports of SSFs from the middle Cambrian and younger deposits. To identify possible factors influencing SSF preservation, five microfacies including bioclastic limestone, flat-pebble conglomerates with bioclasts, hummocky cross-stratified grainstone with bioclasts, bioclastic grainstone in hardgrounds and glauconite bioclastic wackstone-packstone, from Cambrian Series 2 to Miaolingian in North China are compared to assess how differences in lithology impact the preservation potential of SSFs. Our results, based on 35,161 SSF specimens from deposits across six sections, suggest that there are still abundant and diverse SSFs in the middle Cambrian of North China preserved in ways not exclusively reliant on the presence of phosphate and that SSF preservation can be linked to the differences in microfacies in the early to middle Cambrian of North China.This work was financially supported by the National Key Research and Development Program of China (Grant No. 2023YFF0803600) and National Natural Science Foundation of China (Grant Nos. 42302009, 42072003, and W2441016). HYZ thanks the Shaanxi Province postdoctoral research project and China Scholarship Council (202306970031). We also thank the Department of Science and Technology of Shaanxi Province (2022TD-11). TPT also acknowledges the Swedish Research Council (VR2017-05183 and VR2021-04295). This is also a contribution to the project of Theory of Hydrocarbon Enrichment under Multi-Spheric Interactions of the Earth (THEMSIE04010106). </p