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A giant soft-shelled egg from the Late Cretaceous of Antarctica 期刊论文
NATURE, 2020
作者:  Lewnard, Joseph A.;  Lo, Nathan C.;  Arinaminpathy, Nimalan;  Frost, Isabel;  Laxminarayan, Ramanan
收藏  |  浏览/下载:29/0  |  提交时间:2020/06/22

Egg size and structure reflect important constraints on the reproductive and life-history characteristics of vertebrates(1). More than two-thirds of all extant amniotes lay eggs(2). During the Mesozoic era (around 250 million to 65 million years ago), body sizes reached extremes  nevertheless, the largest known egg belongs to the only recently extinct elephant bird(3), which was roughly 66 million years younger than the last nonavian dinosaurs and giant marine reptiles. Here we report a new type of egg discovered in nearshore marine deposits from the Late Cretaceous period (roughly 68 million years ago) of Antarctica. It exceeds all nonavian dinosaur eggs in volume and differs from them in structure. Although the elephant bird egg is slightly larger, its eggshell is roughly five times thicker and shows a substantial prismatic layer and complex pore structure(4). By contrast, the new fossil, visibly collapsed and folded, presents a thin eggshell with a layered structure that lacks a prismatic layer and distinct pores, and is similar to that of most extant lizards and snakes (Lepidosauria)(5). The identity of the animal that laid the egg is unknown, but these preserved morphologies are consistent with the skeletal remains of mosasaurs (large marine lepidosaurs) found nearby. They are not consistent with described morphologies of dinosaur eggs of a similar size class. Phylogenetic analyses of traits for 259 lepidosaur species plus outgroups suggest that the egg belonged to an individual that was at least 7 metres long, hypothesized to be a giant marine reptile, all clades of which have previously been proposed to show live birth(6). Such a large egg with a relatively thin eggshell may reflect derived constraints associated with body shape, reproductive investment linked with gigantism, and lepidosaurian viviparity, in which a '  vestigial'  egg is laid and hatches immediately(7).


A fossil egg unearthed from Cretaceous deposits in Antarctica is more than 20 cm long, exceeds all known nonavian eggs in volume, is soft-shelled, and was perhaps laid by a giant marine lizard such as a mosasaur.


  
A pneumonia outbreak associated with a new coronavirus of probable bat origin 期刊论文
NATURE, 2020, 579 (7798) : 270-+
作者:  Kirchner, James W.;  Berghuijs, Wouter R.;  Allen, Scott T.;  Hrachowitz, Markus;  Hut, Rolf;  Rizzo, Donna M.
收藏  |  浏览/下载:85/0  |  提交时间:2020/07/03

Since the outbreak of severe acute respiratory syndrome (SARS) 18 years ago, a large number of SARS-related coronaviruses (SARSr-CoVs) have been discovered in their natural reservoir host, bats(1-4). Previous studies have shown that some bat SARSr-CoVs have the potential to infect humans(5-7). Here we report the identification and characterization of a new coronavirus (2019-nCoV), which caused an epidemic of acute respiratory syndrome in humans in Wuhan, China. The epidemic, which started on 12 December 2019, had caused 2,794 laboratory-confirmed infections including 80 deaths by 26 January 2020. Full-length genome sequences were obtained from five patients at an early stage of the outbreak. The sequences are almost identical and share 79.6% sequence identity to SARS-CoV. Furthermore, we show that 2019-nCoV is 96% identical at the whole-genome level to a bat coronavirus. Pairwise protein sequence analysis of seven conserved non-structural proteins domains show that this virus belongs to the species of SARSr-CoV. In addition, 2019-nCoV virus isolated from the bronchoalveolar lavage fluid of a critically ill patient could be neutralized by sera from several patients. Notably, we confirmed that 2019-nCoV uses the same cell entry receptor-angiotensin converting enzyme II (ACE2)-as SARS-CoV.


  
What is an endangered species?: judgments about acceptable risk 期刊论文
ENVIRONMENTAL RESEARCH LETTERS, 2020, 15 (1)
作者:  Offer-Westort, Tom;  Feltz, Adam;  Bruskotter, Jeremy T.;  Vucetich, John A.
收藏  |  浏览/下载:19/0  |  提交时间:2020/07/02
conservation policy  conservation values  environmental attitudes  moral foundations theory  political identity  social identity  US endangered species act  
Tree size and local neighbourhood affect foliar nutrient content in a mixed plantation of beech (Fagus sylvatica) and maple (Acer pseudoplatanus) 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2017, 400
作者:  Nickmans, Hans;  Collet, Catherine;  Banal, Damien;  Verheyen, Kris;  Ponette, Quentin
收藏  |  浏览/下载:18/0  |  提交时间:2019/04/09
Forest plantation  Neighbourhood  Density  Species identity  Species diversity  Forest nutrition  Acer pseudoplatanus L.  Fagus sylvatica L.