Ornamental feathers in Cretaceous Burmese amber: resolving the enigma of rachis-dominated feather structure

Xing, Lida; Cockx, Pierre; McKellar, Ryan C.; O’Connor, Jingmai K.

doi:10.1186/s42501-018-0014-2

Cited by 20 publications

(27 citation statements)

References 32 publications

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“…1B). The previously reported Burmese amber-embedded RDFs DIP-V-15125 and DIP-V-16186 (Xing et al 2018) are tentatively assigned by us to morphotype IB RDFs (Table S1).…”

Section: Morphotypes Of the Rdfssupporting

confidence: 55%

“…1C). Most previously reported Burmese amber-embedded RDFs (Xing et al 2018) and all known RDFs recognized in the compressed fossils belong to this morphotype II (Zhang et al 2008b;Wang et al 2014) (Table S1).…”

Section: Morphotypes Of the Rdfsmentioning

confidence: 90%

“…The origin and evolution of feathers are becoming more clear as exquisitely preserved avian-and nonavian, feathered dinosaurs are continuously uncovered from Mesozoic deposits (McKellar et al 2011;Xing et al 2018; O'Connor 2020; Xu 2020). Despite their exceptional preservation, the integuments preserved in compressed fossils are usually taphonomically altered such that detailed feather morphologies are obscured or unpreserved (Xing et al 2017;Yang et al 2019).…”

Section: Taphonomy Effectsmentioning

confidence: 99%

“…The detailed structures of these distinct rachises have traditionally been obscured by the carbonized nature of the compressed fossils (O'Connor et al 2012). Fortunately, recent studies of isolated feathers embedded in early Late Cretaceous Burmese ambers (about 98.8 ± 0.6 million years ago, Cenomanian [Shi et al 2012]) have revealed that the rachises of RDFs are not cylindrical (Xing et al 2018;Carroll et al 2019). Instead, these rachises consist of only the dorsal cortex, lacking the medulla and ventral cortex, and therefore the rachises appear as if they are ventrally opened (Xing et al 2018;Carroll et al 2019).…”

mentioning

confidence: 99%

“…Fortunately, recent studies of isolated feathers embedded in early Late Cretaceous Burmese ambers (about 98.8 ± 0.6 million years ago, Cenomanian [Shi et al 2012]) have revealed that the rachises of RDFs are not cylindrical (Xing et al 2018;Carroll et al 2019). Instead, these rachises consist of only the dorsal cortex, lacking the medulla and ventral cortex, and therefore the rachises appear as if they are ventrally opened (Xing et al 2018;Carroll et al 2019). This unique structure raises the questions of how a rachis without a medulla and a ventral cortex could be formed, and whether this configuration represents a distinct phenotype that evolved independently of the common cylindrical rachidial phenotype (Carroll et al 2019).…”

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confidence: 99%

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Variations of Mesozoic feathers: Insights from the morphogenesis of extant feather rachises

et al. 2020

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The rachises of extant feathers, composed of dense cortex and spongy internal medulla, are flexible and light, yet stiff enough to withstand the load required for flight, among other functions. Incomplete knowledge of early feathers prevents a full understanding of how cylindrical rachises have evolved. Bizarre feathers with unusually wide and flattened rachises, known as “rachis‐dominated feathers” (RDFs), have been observed in fossil nonavian and avian theropods. Newly discovered RDFs embedded in early Late Cretaceous Burmese ambers (about 99 million year ago) suggest the unusually wide and flattened rachises mainly consist of a dorsal cortex, lacking a medulla and a ventral cortex. Coupled with findings on extant feather morphogenesis, known fossil RDFs were categorized into three morphotypes based on their rachidial configurations. For each morphotype, potential developmental scenarios were depicted by referring to the rachidial development in chickens, and relative stiffness of each morphotype was estimated through functional simulations. The results suggest rachises of RDFs are developmentally equivalent to a variety of immature stages of cylindrical rachises. Similar rachidial morphotypes documented in extant penguins suggest that the RDFs are not unique to Mesozoic theropods, although they are likely to have evolved independently in extant penguins.

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“…1B). The previously reported Burmese amber-embedded RDFs DIP-V-15125 and DIP-V-16186 (Xing et al 2018) are tentatively assigned by us to morphotype IB RDFs (Table S1).…”

Section: Morphotypes Of the Rdfssupporting

confidence: 55%

Section: Morphotypes Of the Rdfsmentioning

confidence: 90%

Section: Taphonomy Effectsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Variations of Mesozoic feathers: Insights from the morphogenesis of extant feather rachises

et al. 2020

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Anatomy and Flight Performance of the Early Enantiornithine Bird Protopteryx fengningensis: Information from New Specimens of the Early Cretaceous Huajiying Formation of China

Chiappe

Liu

Serrano

et al. 2019

The Anatomical Record

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The Early Cretaceous (∼131 Million Years Ago) Protopteryx fengningensis is one of the oldest and most primitive enantiornithine birds; however, knowledge of its anatomy has largely been limited to the succinct description of two specimens (holotype and paratype). This study describes two new specimens of P. fengningensis preserving most of the skeleton and plumage, and it therefore adds significantly to understanding the morphology of this important species and the character evolution of enantiornithine birds. The well‐preserved plumage of these specimens also affords a quantitative assessment of the flight performance of P. fengningensis. Our aerodynamic considerations indicate that this early enantiornithine was capable of intermittent flight (bounding or flap‐gliding), thus marking the earliest occurrence of such energy‐saving aerial strategy. Anat Rec, 303:716–731, 2020. © 2019 American Association for Anatomy

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Microstructure and compression resistance of bean goose (Anser fabalis) feather shaft

Zou

Zhou

et al. 2019

Microscopy Res & Technique

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The bean goose Anser fabalis, noted for its excellent flying ability, has feathers composed of keratinized products derived from epidermal cells, which play a crucial role in flight. The feather shaft is an important connective unit, made of a lightweight material, which also contributes to aiding flight. The shaft can withstand loads from different directions and has outstanding compression resistance. In this study, the microstructure and composition of the A. fabalis feather shaft were observed by scanning electron microscopy and Fourier transform infrared spectrometry, and its compression resistance was studied by compression testing. The results indicated that the mechanical property of the shaft is related to its microstructure. Compression testing verified that the primary feathers had the strongest mechanical properties, followed by the secondaries, and finally the alulae. Under the same conditions, the specific energy absorption of the three feather types was 5.96, 5.02, and 3.17 J/g, respectively. With increasing moisture content, the rachis was softened and the energy absorption was reduced. At low moisture content, the specific energy absorption of the primaries was reduced to 1.03 J/g, that of the secondaries was reduced to 1.72 J/g, and that of the alulae to 0.39 J/g. The feather shafts have the advantage of light weight while maintaining the required mechanical properties. These results provide a theoretical and experimental basis for crashworthiness in bionic designs based on the requirements of light weight.

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Ornamental feathers in Cretaceous Burmese amber: resolving the enigma of rachis-dominated feather structure

Cited by 20 publications

References 32 publications

Variations of Mesozoic feathers: Insights from the morphogenesis of extant feather rachises

Variations of Mesozoic feathers: Insights from the morphogenesis of extant feather rachises

Anatomy and Flight Performance of the Early Enantiornithine Bird Protopteryx fengningensis: Information from New Specimens of the Early Cretaceous Huajiying Formation of China

Microstructure and compression resistance of bean goose (Anser fabalis) feather shaft

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