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The genus Barbaria , recently established to accommodate the former Echiniscus bigranulatus group, is a tardigrade group emblematic for the South American tardigrade fauna. This unappendaged echiniscid lineage is widely recognized for the so-called 'double' sculpturing composed of endocuticular pillars and pseudopores or pores in the dorsal cuticle. The phylogenetic relationships in the genus have so far been completely unknown, but the discovery of two new species (B. paucigranulata sp. nov. and B. weglarskae sp. nov.), together with new genetic data for further six species (B. bigranulata , B. charrua comb. nov. , B. danieli , B. jenningsi , B. madonnae and B. ollantaytamboensis), create an opportunity not only to uncover phyletic relationships, but also to reconstruct morphological evolution in the genus. To achieve this, we sequenced five genetic markers (18S rRNA, 28S rRNA, ITS1, ITS2, COI) for multiple populations of eight species of Barbaria (two-thirds of all known species) collected in Alabama (USA), Argentina and the Antarctic, and we analysed them in tandem with detailed morphological data. Our phylogentic analysis and the reconstruction of evolution of morphological traits suggests that the ancestor of the genus inhabited the Neotropics, and it was morphologically most similar to B. bigranulata. We also analyse literature records of Barbaria and conclude that the genus is most likely limited to the Neotropics, Antarctica and southern parts of the Nearctic. The findings are discussed in the context of the phylogeny of the Echiniscus evolutionary line. [ABSTRACT FROM AUTHOR]

Abstract: Clasts of red siltstone with Glossopteris from moraine around Mt Rymill in the southern Prince Charles Mountains, East Antarctica, can be traced upslope in the Lambert Graben system to the nearby Gamburtsev Subglacial Mountains (GSM). The clasts contain zircons with SHRIMP U–Pb ages of 620–460 Ma and 1300–970 Ma from host rocks of intermediate to mafic rocks, and a clay fraction with a T DM Nd model age of 2.72 Ga and εNd of −18.3, derived from upper continental crust. East of the GSM, at Lake Vostok, clasts of siltstone in accreted ice can be traced to the Vostok Subglacial Highlands (VSH). The clasts contain zircons and monazites with SHRIMP U–Pb ages [Leitchenkov, G.L., Belyatsky, B.V., Rodionov, N.V., Sergeev, S.A., 2007. Insight into the geology of the East Antarctic hinterland: a study of mineral inclusions from ice cores of the Lake Vostok borehole. In: Cooper, A.K., Raymond, C.R. (Eds.), Online Proceedings of the 10th ISAES, USGS Open-file Report 2007-1047, Short research Paper 014, 4 pages.] broadly similar to those from Mt Rymill, and a T DM Nd model age of 1.88 Ga and εNd of −15 [Delmonte, B., Petit, J.R., Basile-Doelsch, I., Lipenkov, V., Maggi, V., 2004. First characterization and dating of East Antarctic bedrock inclusions from subglacial Lake Vostok accreted ice. Environmental Chemistry 1, 90–94.]. Other Mesozoic and Paleozoic sediments deposited in a radial pattern about central Antarctica contain detrital zircons dominated by populations aged 700–500 Ma and 1300–1000 Ma, which we interpret as reflecting a GSM-VSH provenance dominated by rocks generated during the Pan-Gondwanaland and Grenville events of supercontinental assembly. [Copyright &y& Elsevier]

New whole rock Rb-Sr and zircon U-Pb geochronological data and Sm-Nd isotopic data are presented from the central magmatic arc domain of the Antarctic Peninsula in the area of north-west Palmer Land and south-west Graham Land, Rb-Sr isochrons indicate an age of 169 ± 6 Ma for basement orthogneisses and 132 ± 9 to 71 ± 9Ma for plutons. A U-Pb age of 183 ± 2.1 Ma, with no detectable inheritance, on zircons from an orthogneiss from Cape Berteaux provides the first reliable age for the orthogneisses, which are interpreted as metamorphosed silicic volcanic rocks, and Sm-Nd data indicate derivation in a mature volcanic arc. The age indicates they may be correlatives of the Jurassic 'Chon Aike' volcanism of the eastern Antarctic Peninsula. A U-Pb zircon age of 107 ± 1.7 Ma on a terrestrial volcanic sequence overlying an uncomformity strongly suggests a mid-Cretaceous age for the extensive volcanic cover of north-west Palmer Land that was previously thought to be Jurassic. The unconformity is interpreted to have been a result of compressional uplift related to the Palmer Land event. This is the first date for the event in the western part of the central magmatic arc terrane of the Antarctic Peninsula. [ABSTRACT FROM AUTHOR]

Zircon and apatite fission track (AFT) thermochronology was applied to the James Ross Basin sedimentary rocks from James Ross and Seymour islands. The probable sources of these sediments were generated in Carboniferous to Early Paleogene times (∼315 to 60 Ma). The total depths of individual James Ross Basin formations are discussed. The AFT data were modelled, and the thermal history model was reconstructed for samples from Seymour Island. The first stage after a period of total thermal annealing (when the samples were above 120°C) involved Late Triassic cooling (∼230 to 200 Ma) and is followed by a period of steady cooling through the whole apatite partial annealing zone (PAZ, 60-120°C) to minimum temperature in Paleocene/Early Eocene. The next stage was the maximum burial of sedimentary rocks in the Eocene (∼35 Ma, 1.1-1.8 km) and the final cooling and uplift of Seymour Island sedimentary rocks at ∼35 to 20 Ma. [ABSTRACT FROM AUTHOR]