The avian nature of the brain and inner ear of Archaeopteryx

Archaeopteryx, the earliest known flying bird (avialan) from the Late Jurassic period, exhibits many shared primitive characters with more basal coelurosaurian dinosaurs (the clade including all theropods more bird-like than Allosaurus), such as teeth, a long bony tail and pinnate feathers. However, Archaeopteryx possessed asymmetrical flight feathers on its wings and tail, together with a wing feather arrangement shared with modern birds. This suggests some degree of powered flight capability but, until now, little was understood about the extent to which its brain and special senses were adapted for flight. We investigated this problem by computed tomography scanning and three-dimensional reconstruction of the braincase of the London specimen of Archaeopteryx. Here we show the reconstruction of the braincase from which we derived endocasts of the brain and inner ear. These suggest that Archaeopteryx closely resembled modern birds in the dominance of the sense of vision and in the possession of expanded auditory and spatial sensory perception in the ear. We conclude that Archaeopteryx had acquired the derived neurological and structural adaptations necessary for flight. An enlarged forebrain suggests that it had also developed enhanced somatosensory integration with these special senses demanded by a lifestyle involving flying ability.     

A uniquely specialized ear in a very early tetrapod

The Late Devonian genus Ichthyostega was for many decades the earliest known tetrapod, and the sole representative of a transitional form between a fish and a land vertebrate. However, despite being known since 1932 (ref. 1) from a large collection of specimens, its morphology remained enigmatic and not what was expected of a very primitive tetrapod. Its apparent specializations led it to be considered as a "blind offshoot" or "sidebranch" off the tetrapod family tree, and recent cladistic analyses have disagreed about its exact phylogenetic position within the tetrapod stem group. In particular, its braincase and ear region defied interpretation, such that conventional anatomical terms seemed inapplicable. Using new material collected in 1998 (ref. 9), preparation of earlier-collected material, and high-resolution computed tomography scanning, here we identify and interpret these problematic anatomical structures. They can now be seen to form part of a highly specialized ear, probably a hearing device for use in water. This represents a structurally and functionally unique modification of the tetrapod otic region, unlike anything seen in subsequent tetrapod evolution. The presence of deeply grooved gill bars as in its contemporary Acanthostega suggest that Ichthyostega may have been more aquatically adapted than previously believed.     

Systemic Research Practices Towards the Development of an Eco-Community in Vietnam: some Joint Post-Facto Reflections

In this article we discuss how an interdisciplinary research team partnered with a variety of stakeholders concerned with and/or affected by the impacts of climate change in the Red River Delta of Vietnam. The research, undertaken from 2016 to 2018, drew upon a wide range of methods to investigate systemically these impacts – with a view to the research inputting into the development of (more) sustainable ways of living. The research solicited various accounts of the experience of climate change in the community, set up learning processes in community meetings, and created an interface with government officials positioned at commune, district, provincial, and national levels. The intention was to offer support towards developing a learning process (broadly defined as including learnings/systemic inquiry across organizational levels of the society) to pursue options for sustainable living. The article offers our post-facto reflections which render more explicit (to ourselves and for the benefit of audiences) how the research team, with Hoang as lead researcher, facilitated the inquiry process towards developing a synthesis which underscored the assets for resilience to climate change and supported interventions to strengthen such (defined) assets.

     

Definitive fossil evidence for the extant avian radiation in the Cretaceous

Long-standing controversy surrounds the question of whether living bird lineages emerged after non-avian dinosaur extinction at the Cretaceous/Tertiary (K/T) boundary or whether these lineages coexisted with other dinosaurs and passed through this mass extinction event. Inferences from biogeography and molecular sequence data (but see ref. 10) project major avian lineages deep into the Cretaceous period, implying their 'mass survival' at the K/T boundary. By contrast, it has been argued that the fossil record refutes this hypothesis, placing a 'big bang' of avian radiation only after the end of the Cretaceous. However, other fossil data--fragmentary bones referred to extant bird lineages--have been considered inconclusive. These data have never been subjected to phylogenetic analysis. Here we identify a rare, partial skeleton from the Maastrichtian of Antarctica as the first Cretaceous fossil definitively placed within the extant bird radiation. Several phylogenetic analyses supported by independent histological data indicate that a new species, Vegavis iaai, is a part of Anseriformes (waterfowl) and is most closely related to Anatidae, which includes true ducks. A minimum of five divergences within Aves before the K/T boundary are inferred from the placement of Vegavis; at least duck, chicken and ratite bird relatives were coextant with non-avian dinosaurs.     

本溪地区BIF中玄武质围岩的高场强元素特征

辽宁本溪地区条带状铁矿(BIF)与其玄武质火山围岩之间的时空关联非常密切.对于玄武质火山围岩高场强元素(HFSE)的研究表明:wNb/wTa比值(7.00~19.93)表现出明显的分异,而wZr/wHf比值(33.46~38.28)则变化不大;从弓长岭到南芬、歪头山样品的wNb/wTa比值变化具有明显的循序性.这种高场强元素的迁移和分异特征反映出俯冲作用与盆地演化之间的关联.研究区玄武质火山围岩(wNb/wYb)N比值大于1(1.21~18.45,平均2.72),这进一步表明,其形成的构造背景为陆内弧后盆地提供了有利于BIF形成的条件.     

基于热压块的不锈钢粉尘还原实验

为了从不锈钢粉尘中回收利用Fe,Cr和Ni等,对不锈钢粉尘热压块制备及其自还原过程进行了研究.在热压温度为200℃,热压压力为35 MPa条件下,抗压强度达到900 N/个以上.高温条件下,煤热解产生的挥发分可参与不锈钢粉尘还原反应,当还原温度为1 400,1 450℃时,挥发分还原作用率达到0.4.据XRD分析和热力学计算,自还原过程中含铬物质的物相转变顺序为Fe Cr2O4,Cr2O3,Cr7C3,[Cr]Fe-Cr-Ni-C.当还原温度为1 450℃,烟煤中固定碳与粉尘中可去除氧的物质量的比(xc/xo)为0.72时,不锈钢粉尘热压块不能完全还原;当xc/xo大于0.8,还原20 min时,不锈钢粉尘热压块能完全还原.     

Forensic palaeontology: The Archaeoraptor forgery

The Archaeoraptor fossil was announced as a 'missing link' and purported to be possibly the best evidence since Archaeopteryx that birds did, in fact, evolve from certain types of carnivorous dinosaur. It reportedly came from Early Cretaceous beds of China that have produced other spectacular fossils transitional between birds and extinct non-avian dinosaurs. But Archaeoraptor was revealed to be a forgery in which bones of a primitive bird and a non-flying dromaeosaurid dinosaur had been combined. Here we use high-resolution X-ray computed tomography (CT) to determine the nature and extent of the forgery, as well as how it was built, by imaging the fracture pattern and distribution of materials through the entire specimen.