Some mainly new non-dino papers:
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Johann P. Klages, Ulrich Salzmann, Torsten Bickert, Claus-Dieter Hillenbrand, Karsten Gohl, Gerhard Kuhn, Steven M. Bohaty, JÃrgen Titschack, Juliane MÃller, Thomas Frederichs, Thorsten Bauersachs, Werner Ehrmann, Tina van de Flierdt, Patric SimÃes Pereira, Robert D. Larter, Gerrit Lohmann, Igor Niezgodzki, Gabriele Uenzelmann-Neben, Maximilian Zundel, Cornelia Spiegel, Chris Mark, David Chew, Jane E. Francis, Gernot Nehrke, Florian Schwarz, James A. Smith, Tim Freudenthal, Oliver Esper, Heiko PÃlike, Thomas A. Ronge, Ricarda Dziadek & the Science Team of Expedition PS104 (V. Afanasyeva, J. E. Arndt, B. Ebermann, C. Gebhardt, K. Hochmuth, K. KÃssner, Y. Najman, F. Riefstahl & M. Scheinert) (2020)
Temperate rainforests near the South Pole during peak Cretaceous warmth.
Nature 580: 81--86
DOI:
https://doi.org/10.1038/s41586-020-2148-5https://www.nature.com/articles/s41586-020-2148-5The mid-Cretaceous period was one of the warmest intervals of the past 140 million years, driven by atmospheric carbon dioxide levels of around 1,000 parts per million by volume. In the near absence of proximal geological records from south of the Antarctic Circle, it is disputed whether polar ice could exist under such environmental conditions. Here we use a sedimentary sequence recovered from the West Antarctic shelf--the southernmost Cretaceous record reported so far--and show that a temperate lowland rainforest environment existed at a palaeolatitude of about 82Â S during the Turonian-Santonian age (92 to 83 million years ago). This record contains an intact 3-metre-long network of in situ fossil roots embedded in a mudstone matrix containing diverse pollen and spores. A climate model simulation shows that the reconstructed temperate climate at this high latitude requires a combination of both atmospheric carbon dioxide concentrations of 1,120-1,680 parts per million by volume and a vegetated land surface without major Antarctic glaciation, highlighting the important cooling effect exerted by ice albedo under high levels of atmospheric carbon dioxide.
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video:
Antarctica's ice hides an ancient rainforest
Fossilised roots reveal that a lush Cretaceous forest once thrived near the South Pole.
News:Â
Traces of ancient rainforest in Antarctica point to a warmer prehistoric world
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The partial skeleton of a new extinct taxon, Linxiavis inaquosus, from the Liushu Formation (6-9 Ma) at the edge of the Tibetan Plateau in Gansu Province, China is the most substantial known fossil record of sandgrouse (Pteroclidae). While adding to the rapidly growing known Liushu avian fauna of vultures, falcons, pheasants, and ostrich, this new fossil is likely the oldest record of crown Pteroclidae (as a potential molecular clock calibration point), the oldest record of the group in Asia (from a probable African origin), and derives from a significant temporal gap in their Neogene history. The fossil specimen includes articulated and associated elements of the wings, shoulder girdle, vertebrae, and hind limb, exhibiting apomorphies of Columbiformes and Pteroclidae such as a notarium, and a short coracoid shaft. As part of the diverse Hipparion fauna, Linxiavis inaquosus reinforces the interpretation of the late Miocene Linxia Basin habitat as an arid savannah, associated with the uplift of the Tibetan Plateau. The holotype suggests that the arid high elevation Tibetan area habitats may have been continuously occupied since the late Miocene by sandgrouse carrying water in their modified breast feathers to their young.
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Cas Jorissen, Eric Paillet, Jan Scholliers, Peter Aerts & Jana Goyens (2020)
Head stabilization in small vertebrates that run at high frequencies with a sprawled posture.
Biological Journal of the Linnean Society, blaa034 (advance online publication)
doi:
https://doi.org/10.1093/biolinnean/blaa034https://academic.oup.com/biolinnean/advance-article-abstract/doi/10.1093/biolinnean/blaa034/5814120 Small animals face a large challenge when running. A stable head is key to maintenance of a stable gaze and a good sense of self-motion and spatial awareness. However, trunk undulations caused by the cyclic limb movements result in involuntary head movements. Hence, the head needs to be stabilized. Humans are capable of stabilizing their head up to 2-3 Hz, but small animals run at cycle frequencies that are up to six times higher. We wondered how natural selection has adapted their head stabilization control. We observed that the relative contributions of vision, on the one hand, and vestibular perception and proprioception, on the other hand, remain the same when lizards undergo fast or slow body undulations in an experimental set-up. Lizards also maintain a short phase lag at both low and high undulation frequencies. Hence, we found no indication that they use a different control mechanism at high frequencies. Instead, head stabilization probably remains possible owing to faster reflex pathways and a lower head inertia. Hence, the intrinsic physical and neurological characteristics of lizards seem to be sufficient to enable head stabilization at high frequencies, obviating the need for evolutionary adaptation of the control pathways. These properties are not unique to lizards and might, therefore, also facilitate head stabilization at high frequencies in other small, fast animals.
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Margot Bon, Carla Bardua, Anjali Goswami & Anne-Claire Fabre (2020)
Cranial integration in the fire salamander, Salamandra salamandra (Caudata: Salamandridae)
Biological Journal of the Linnean Society, blaa020
doi:
https://doi.org/10.1093/biolinnean/blaa020https://academic.oup.com/biolinnean/advance-article-abstract/doi/10.1093/biolinnean/blaa020/5813588Phenotypic integration and modularity are concepts that represent the pattern of connectivity of morphological structures within an organism. Integration describes the coordinated variation of traits, and analyses of these relationships among traits often reveals the presence of modules, sets of traits that are highly integrated but relatively independent of other traits. Phenotypic integration and modularity have been studied at both the evolutionary and static level across a variety of clades, although most studies thus far are focused on amniotes, and especially mammals. Using a high-dimensional geometric morphometric approach, we investigated the pattern of cranial integration and modularity of the Italian fire salamander (Salamandra salamandra giglioli). We recovered a highly modular pattern, but this pattern did not support either entirely developmental or functional hypotheses of cranial organisation, possibly reflecting complex interactions amongst multiple influencing factors. We found that size had no significant effect on cranial shape, and that morphological variance of individual modules had no significant relationship with degree of within-module integration. The pattern of cranial integration in the fire salamander is similar to that previously recovered for caecilians, with highly integrated jaw suspensorium and occipital regions, suggesting possible conservation of patterns across lissamphibians.