Insight into the early evolution of the avian sternum from juvenile enantiornithines

Zheng, Xiaoting; Wang, Xiaoli; O’Connor, Jingmai K.; Zhou, Zhonghe

doi:10.1038/ncomms2104

Cited by 74 publications

(73 citation statements)

References 39 publications

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“…The origin of the modern flight feather-characterized by small barb angles in cutting-edge vanes and larger barb angles in trailing vanes-is coincident with the inferred origin of multiple flight-related features, such as the alula and an ossified sternal keel [40,41]. These features arose subsequent to the origin of other hypothesized flight-related specializations such as the elongation of the coracoid, the acquisition of a fused pygostyle and the initial acquisition of asymmetrical flight feathers themselves [4].…”

Section: (C) Mesozoic Stem Birdsmentioning

confidence: 91%

Barb geometry of asymmetrical feathers reveals a transitional morphology in the evolution of avian flight

2015

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The geometry of feather barbs (barb length and barb angle) determines feather vane asymmetry and vane rigidity, which are both critical to a feather's aerodynamic performance. Here, we describe the relationship between barb geometry and aerodynamic function across the evolutionary history of asymmetrical flight feathers, from Mesozoic taxa outside of modern avian diversity (Microraptor, Archaeopteryx, Sapeornis, Confuciusornis and the enantiornithine Eopengornis) to an extensive sample of modern birds. Contrary to previous assumptions, we find that barb angle is not related to vane-width asymmetry; instead barb angle varies with vane function, whereas barb length variation determines vane asymmetry. We demonstrate that barb geometry significantly differs among functionally distinct portions of flight feather vanes, and that cutting-edge leading vanes occupy a distinct region of morphospace characterized by small barb angles. This cutting-edge vane morphology is ubiquitous across a phylogenetically and functionally diverse sample of modern birds and Mesozoic stem birds, revealing a fundamental aerodynamic adaptation that has persisted from the Late Jurassic. However, in Mesozoic taxa stemward of Ornithurae and Enantiornithes, trailing vane barb geometry is distinctly different from that of modern birds. In both modern birds and enantiornithines, trailing vanes have larger barb angles than in comparatively stemward taxa like Archaeopteryx, which exhibit small trailing vane barb angles. This discovery reveals a previously unrecognized evolutionary transition in flight feather morphology, which has important implications for the flight capacity of early feathered theropods such as Archaeopteryx and Microraptor. Our findings suggest that the fully modern avian flight feather, and possibly a modern capacity for powered flight, evolved crownward of Confuciusornis, long after the origin of asymmetrical flight feathers, and much later than previously recognized.

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Section: (C) Mesozoic Stem Birdsmentioning

confidence: 91%

Barb geometry of asymmetrical feathers reveals a transitional morphology in the evolution of avian flight

2015

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“…S3A) and is inferred to have articulated on the lateral surface, functioning as lateral trabeculae although in no specimen are the "lateral trabeculae" fused to the sternum (20), and their in vivo articulation with the sternal body is unknown (20,21). Four to five pairs of sternal ribs articulated with the sternum; costal facets appear not to be developed (present in some nonavian theropods, the basal bird Confuciusornis, and ornithuromorphs) (22)(23)(24).…”

Section: Resultsmentioning

confidence: 99%

On the absence of sternal elements in Anchiornis (Paraves) and Sapeornis (Aves) and the complex early evolution of the avian sternum

Zheng

O’Connor

Wang

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Anchiornis (Deinonychosauria: Troodontidae), the earliest known feathered dinosaur, and Sapeornis (Aves: Pygostylia), one of the basalmost Cretaceous birds, are both known from hundreds of specimens, although remarkably not one specimen preserves any sternal ossifications. We use histological analysis to confirm the absence of this element in adult specimens. Furthermore, the excellent preservation of soft-tissue structures in some specimens suggests that no chondrified sternum was present. Archaeopteryx, the oldest and most basal known bird, is known from only 10 specimens and the presence of a sternum is controversial; a chondrified sternum is widely considered to have been present. However, data from Anchiornis and Sapeornis suggest that a sternum may also have been completely absent in this important taxon, suggesting that the absence of a sternum could represent the plesiomorphic avian condition. Our discovery reveals an unexpected level of complexity in the early evolution of the avian sternum; the large amount of observable homoplasy is probably a direct result of the high degree of inherent developmental plasticity of the sternum compared with observations in other skeletal elements.Maniraptora | Mesozoic | Jehol | flight | histology

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“…The battery delivers a reversible discharge capacity of 1250 mAh g −1 at current rate of 0.1 C that slowly reduced to 1130 mAh g −1 at 0.2 C , 930 mAh g −1 at 0.5 C , 753 mAh g −1 at 1 C , and 685 mAh g −1 at 2 C . Even at high rate of 4 C (6680 mA g −1 ), the leaf‐like GO/S cathode still can deliver a capacity of 468 mAh g −1 , which is almost the best rate performance of C/S composite cathode 8, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 45, 46, 48, 51, 52, 53…”

Section: Resultsmentioning

confidence: 93%

“…Based on the result of self‐discharge investigation, leaf‐like GO/S composites can largely limit the self‐discharge of Li–S battery. However, to further reduce the self‐discharge of Li–S batteries, a synergy of methods are still needed such as optimizing the electrolyte,7, 8 designing new battery structure,52, 53 protecting Li anode,54, 55 and spatially controlling sulphur species deposition 56. For comparison, conventional GO/S composite was synthesized and investigated as electrode for Li–S battery (Figure S9, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Leaf‐Like Graphene‐Oxide‐Wrapped Sulfur for High‐Performance Lithium–Sulfur Battery

et al. 2015

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Carbon/sulfur composites are attracting extensive attention because of their improved performances for Li–S batteries. However, the achievements are generally based on the low S‐content in the composites and the low S‐loading on the electrode. Herein, a leaf‐like graphene oxide (GO), which includes an inherent carbon nanotube midrib in the GO plane, is synthesized for preparing GO/S composites. Owing to the inherent high conductivity of carbon nanotube midribs and the abundant surface groups of GO for S‐immobilization, the composite with an S‐content of 60 wt% exhibits ultralong cycling stability over 1000 times with a low capacity decay of 0.033% per cycle and a high rate up to 4C. When the S‐content is increased to 75 wt%, the composite still shows a perfect cycling performance over 1000 cycles. Even with the high S‐loading of 2.7 mg cm−2 on the electrode and the high S‐content of 85 wt%, it still shows a promising cycling performance over 600 cycles.

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Insight into the early evolution of the avian sternum from juvenile enantiornithines

Cited by 74 publications

References 39 publications

Barb geometry of asymmetrical feathers reveals a transitional morphology in the evolution of avian flight

Barb geometry of asymmetrical feathers reveals a transitional morphology in the evolution of avian flight

On the absence of sternal elements in Anchiornis (Paraves) and Sapeornis (Aves) and the complex early evolution of the avian sternum

Leaf‐Like Graphene‐Oxide‐Wrapped Sulfur for High‐Performance Lithium–Sulfur Battery

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