40 research outputs found

    The first record of Upper Permian and Lower Triassic scorpions from Russia (Chelicerata: Scorpiones)

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    Several small fragments of fossil scorpions are reported from two localities in Vologda Province, Russia, representing the Upper Permian (Severodvinian, correlated to Wuchiapingian) (Isady) and Lower Triassic just above the Permian-Triassic boundary (Induan) (Nedubrovo). Most observed structures are not diagnostic at genus or family level. The Isady leg fragment possesses ungues (claws), which are both denticulated and setaceous, and resembles a Carboniferous Eobuthus sp. (Eobuthidae). It is the latest record of this type of ungues, which are known in some Paleozoic scorpions (extinct suborder Mesoscorpiones); all extant scorpions have smooth claws without denticulation or setation

    A scorpion from a peatbog: the first arthropod fossil from the Late Viséan of the Moscow Coal Basin

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    This note describes a fossil fragment from the Upper Viséan (ca. 330 Ma), of the Moscow Coal Basin (Novgorod Region, Russia). The fossil is identified as the cuticle of a single leg segment (left femur) of a scorpion (Arachnida: Scorpiones), without any further taxonomic placement. The anatomical details of the fragment are given, along with ecological considerations. It is the first fossil scorpion record from Russia

    New austrolimulid from Russia supports role of Early Triassic horseshoe crabs as opportunistic taxa

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    Horseshoe crabs are extant marine euchelicerates that have a fossil record extending well into the Palaeozoic. Extreme xiphosurid morphologies arose during this evolutionary history. These forms often reflected the occupation of freshwater or marginal conditions. This is particularly the case for Austrolimulidae—a xiphosurid family that has recently been subject to thorough taxonomic examination. Expanding the austrolimulid record, we present new material from the Olenekian-aged Petropavlovka Formation in European Russia and assign this material to Attenborolimulus superspinosus gen. et sp. nov. A geometric morphometric analysis of 23 horseshoe crab genera illustrates that the new taxon is distinct from limulid and paleolimulid morphologies, supporting the assignment within Austrolimulidae. In considering Triassic austrolimulids, we suggest that the hypertrophy or reduction in exoskeletal sections illustrate how species within the family evolved as opportunistic taxa after the end-Permian extinction

    Distinct magneto-Raman signatures of spin-flip phase transitions in CrI3_{3}

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    The discovery of 2-dimensional (2D) materials, such as CrI3_{3}, that retain magnetic ordering at monolayer thickness has resulted in a surge of both pure and applied research in 2D magnetism. Here, we report a magneto-Raman spectroscopy study on multilayered CrI3_{3}, focusing on two additional features in the spectra that appear below the magnetic ordering temperature and were previously assigned to high frequency magnons. Instead, we conclude these modes are actually zone-folded phonons. We observe a striking evolution of the Raman spectra with increasing magnetic field applied perpendicular to the atomic layers in which clear, sudden changes in intensities of the modes are attributed to the interlayer ordering changing from antiferromagnetic to ferromagnetic at a critical magnetic field. Our work highlights the sensitivity of the Raman modes to weak interlayer spin ordering in CrI3_{3}

    Distinct magneto-Raman signatures of spin-flip phase transitions in CrI3

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    The discovery of 2-dimensional (2D) materials, such as CrI3, that retain magnetic ordering at monolayer thickness has resulted in a surge of research in 2D magnetism from both pure and applied perspectives. Here, we report a magneto-Raman spectroscopy study on multilayered CrI3, focusing on two new features in the spectra which appear at temperatures below the magnetic ordering temperature and were previously assigned to high frequency magnons. We observe a striking evolution of the Raman spectra with increasing magnetic field in which clear, sudden changes in intensities of the modes are attributed to the interlayer ordering changing from antiferromagnetic to ferromagnetic at a critical magnetic field. Our work highlights the sensitivity of the Raman modes to weak interlayer spin ordering in CrI3. In addition, we theoretically examine potential origins for the new modes, which we deduce are unlikely single magnons

    Composition, crystallization conditions and genesis of sulfide-saturated parental melts of olivine-phyric rocks from Kamchatsky Mys (Kamchatka, Russia)

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    Highlights ‱ Parental melts of sulfide-bearing KM rocks have near primary MORB-like composition. ‱ Crystallization of these S-saturated melts occurred in near-surface conditions. ‱ Extensive fractionation and crustal assimilation are not the causes of S-saturation. ‱ S content in melts can be restored by accounting for daughter sulfide globules. Abstract Sulfide liquids that immiscibly separate from silicate melts in different magmatic processes accumulate chalcophile metals and may represent important sources of the metals in Earth's crust for the formation of ore deposits. Sulfide phases commonly found in some primitive mid-ocean ridge basalts (MORB) may support the occurrence of sulfide immiscibility in the crust without requiring magma contamination and/or extensive fractionation. However, the records of incipient sulfide melts in equilibrium with primitive high-Mg olivine and Cr-spinel are scarce. Sulfide globules in olivine phenocrysts in picritic rocks of MORB-affinity at Kamchatsky Mys (Eastern Kamchatka, Russia) represent a well-documented example of natural immiscibility in primitive oceanic magmas. Our study examines the conditions of silicate-sulfide immiscibility in these magmas by reporting high precision data on the compositions of Cr-spinel and silicate melt inclusions, hosted in Mg-rich olivine (86.9–90 mol% Fo), which also contain globules of magmatic sulfide melt. Major and trace element contents of reconstructed parental silicate melts, redox conditions (ΔQFM = +0.1 ± 0.16 (1σ) log. units) and crystallization temperature (1200–1285 °C), as well as mantle potential temperatures (~1350 °C), correspond to typical MORB values. We show that nearly 50% of sulfur could be captured in daughter sulfide globules even in reheated melt inclusions, which could lead to a significant underestimation of sulfur content in reconstructed silicate melts. The saturation of these melts in sulfur appears to be unrelated to the effects of melt crystallization and crustal assimilation, so we discuss the reasons for the S variations in reconstructed melts and the influence of pressure and other parameters on the SCSS (Sulfur Content at Sulfide Saturation)

    Fulgobole evansi Shcherbakov 2011, sp. nov.

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    Fulgobole evansi sp. nov. Fig. 13 Material. Holotype PIN 2555 / 2228, right tegmen, Dzhailoucho. Paratypes PIN 2240 / 2746, 2555/2762, 2785/ 3238, tegmina, Dzhailoucho; PIN 2971 / 181 ±, tegmen, Madygen (SW area). Description. Tegmen moderately elongate, usually not widening distally, broadly rounded apically, 7.7–12.4 mm long, pale, with dark spot in stigmal area. Surface faintly, sparsely punctate, more distinctly so at base and on clavus. Costal margin convex proximally, straight distally; costal space moderately broad. RA beyond nodus diverging from margin, some of anterior RA branches deeply forked. R forked before tegmen midlength, CuA usually more distally, M just before or beyond nodal crossveins, RP and CuA 1 at same level or more distally than M (rarely more proximally – PIN 2785 / 3482). Space between CuA 1 and CuA 2 more or less narrowed at nodal level. CuA 2 shorter than CuA 1, simple or with short branches. RP, M, and CuA altogether with 15–19 terminations. Margin crimpled in stigmal area. Etymology. After entomologist John W. Evans.Published as part of Shcherbakov, Dmitry E., 2011, New and little-known families of Hemiptera Cicadomorpha from the Triassic of Central Asia — early analogs of treehoppers and planthoppers, pp. 1-26 in Zootaxa 2836 on pages 20-21, DOI: 10.5281/zenodo.32012

    FIGURE 1 in A peculiar new genus of Scytinopteridae (Hemiptera, Cicadomorpha) from the Permian-Triassic boundary beds of Mongolia

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    FIGURE 1. Beloscyta edi gen. et sp. nov., A–F, Holotype tegmen, A–D, SEM (BSE), E, Photograph, A, D, E, Part (images flipped), B, C, Counterpart. A, E, Whole tegmen. B, Base. C, Surface sculpture. D, Apex. F, Venation. G, Paratype (photograph). Scale bars = 1 mm (A, E–G), 0.4 mm (B), 0.2 mm (C, D).Published as part of SHCHERBAKOV, DMITRY E., 2022, A peculiar new genus of Scytinopteridae (Hemiptera, Cicadomorpha) from the Permian-Triassic boundary beds of Mongolia, pp. 218-221 in Palaeoentomology 5 (3) on page 219, DOI: 10.11646/palaeoentomology.5.3.2, http://zenodo.org/record/682080

    Fasolinka beckermigdisovae Shcherbakov 2011, sp. nov.

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    Fasolinka beckermigdisovae sp. nov. Fig. 8 Material. Holotype PIN 2785 / 3087 (3115) & 3088 (3096), right and left tegmina of same specimen on one rock slab, Dzhailoucho. Paratypes: PIN 2240 / 2904 ±, 3707 ±, tegmina, Dzhailoucho; PIN 2083 /256, 2971/ 553 ±, tegmina, and 2971 / 381 ±, insect without head and prothorax, Madygen (SW area). Description. Tegmen elongate, convex, 8.0–11.0 mm long. Surface pitted, less deeply so near apex. Interradial space narrowing apically; MA with narrow fork; RP and MA 1 widely separated. CuA 1 joining M at or before its bifurcation. Basal cell closed by short arculus or short M+CuA anastomosis. Marginal membrane pitted. Remarks. Both tegmina from the southwestern area have the postnodal part narrow, with the MA fork and the apex of interradial space distinctly narrower than in the tegmina from Dzhailoucho. Etymology. After paleoentomologist Elena E. Becker-Migdisova.Published as part of Shcherbakov, Dmitry E., 2011, New and little-known families of Hemiptera Cicadomorpha from the Triassic of Central Asia — early analogs of treehoppers and planthoppers, pp. 1-26 in Zootaxa 2836 on pages 12-13, DOI: 10.5281/zenodo.32012
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