Recent advances have deepened our understanding of the evolutionary and developmental origins of feather branching architectures.However,the internal tissue differentiation within these branches has received limited a...Recent advances have deepened our understanding of the evolutionary and developmental origins of feather branching architectures.However,the internal tissue differentiation within these branches has received limited attention.This study examined eight fossilized feathers preserved in early Late Cretaceous Burmese amber,characterized by barb rami composed entirely of cortical tissue with no internal medulla.Based on barb rami morphology,the feathers were categorized into three distinct morphotypes.Comparative analysis with feather development in extant chickens suggested minimal tissue differentiation in these early feathers.Functional simulations further revealed that modern barb rami configurations provide greater aerodynamic stability than medulla-free early feathers under most conditions,highlighting flexural stiffness as a key factor in the evolution of feather branches.The presence of medullafree barb rami suggests that although the three-level hierarchical branching pattern characteristic of modern feathers had emerged by the Jurassic,tissue differentiation within feather branches remained developmentally unstable during the Late Cretaceous.This instability likely contributed to the structural variability of early feathers,enabling morphologies that no longer persist in modern birds.展开更多
We investigate how the barb of bird feathers is changed along both the rachis and barb.To investigate the microstructures and the mechanical behaviors of barbs,a series of barbs are manually cut from an eagle’s prima...We investigate how the barb of bird feathers is changed along both the rachis and barb.To investigate the microstructures and the mechanical behaviors of barbs,a series of barbs are manually cut from an eagle’s primary feather to observe the cross sections.Aλ-like cross section with a tiny hook is observed at the right feet at each section.Afterwards,a measurement of the setup system is developed to evaluate the leakage ratio of a feather followed by a numerical predicting approach based on the CFD method.It is found that the air leakage increases linearly against the pressure,and the predicted results coincide well with the experimental results.Finally,the influences of leakage of the flight feather on both steady and unsteady aerodynamics are studied.展开更多
Feathers are critical for the flight of birds.A feather comprises a rachis and two rows of barbs on each side of the rachis[1,2].Each side of the barbs features a row of barbules.In extant flying birds,the ventral sid...Feathers are critical for the flight of birds.A feather comprises a rachis and two rows of barbs on each side of the rachis[1,2].Each side of the barbs features a row of barbules.In extant flying birds,the ventral side of the distal half of the distal barbule bears several hook-like structures called hooklets,while the dorsal side of the proximal barbule curves into a narrow groove,creating a specialized interlocking hook-and-groove mechanism that resists tearing force from the air during flight[[2],[3],[4]].展开更多
基金supported by the Human Frontier Science Program (LT000728/2018)Zijiang Program for Talented Scholars at East China Normal UniversityShanghai Pujiang Program (23PJ1402300)
文摘Recent advances have deepened our understanding of the evolutionary and developmental origins of feather branching architectures.However,the internal tissue differentiation within these branches has received limited attention.This study examined eight fossilized feathers preserved in early Late Cretaceous Burmese amber,characterized by barb rami composed entirely of cortical tissue with no internal medulla.Based on barb rami morphology,the feathers were categorized into three distinct morphotypes.Comparative analysis with feather development in extant chickens suggested minimal tissue differentiation in these early feathers.Functional simulations further revealed that modern barb rami configurations provide greater aerodynamic stability than medulla-free early feathers under most conditions,highlighting flexural stiffness as a key factor in the evolution of feather branches.The presence of medullafree barb rami suggests that although the three-level hierarchical branching pattern characteristic of modern feathers had emerged by the Jurassic,tissue differentiation within feather branches remained developmentally unstable during the Late Cretaceous.This instability likely contributed to the structural variability of early feathers,enabling morphologies that no longer persist in modern birds.
基金Project supported by the National Natural Science Foundation of China(Grant No.51705459)the Natural Science Foundation of Zhejiang Province,China(Grant No.LY20E050022).
文摘We investigate how the barb of bird feathers is changed along both the rachis and barb.To investigate the microstructures and the mechanical behaviors of barbs,a series of barbs are manually cut from an eagle’s primary feather to observe the cross sections.Aλ-like cross section with a tiny hook is observed at the right feet at each section.Afterwards,a measurement of the setup system is developed to evaluate the leakage ratio of a feather followed by a numerical predicting approach based on the CFD method.It is found that the air leakage increases linearly against the pressure,and the predicted results coincide well with the experimental results.Finally,the influences of leakage of the flight feather on both steady and unsteady aerodynamics are studied.
基金supported by the National Natural Science Foundation of China(32400364,42202025,42288201,42072030,and 42302020)the China Postdoctoral Science Foundation(E41ZJ51135)+7 种基金the BJAST Young Scholar Programs(24CE-YS-01)the special financial support of the Beijing Governmentthe National Key R&D Program of China(2022YFC2601200)the Fundamental Research Funds for the Liaoning Universities(LJ202410166028)the National Science&Technology Fundamental Resources Investigation Program of China(2022FY100500 and 2023FY100301)the Institute of Zoology,Chinese Academy of Sciences(2023IOZ0104)the State Key Laboratory of Animal Biodiversity Conservation and Integrated Pest Management(SKLA2502)the Survey of Wildlife Resources in Key Areas of Xizang(ZL202203601).
文摘Feathers are critical for the flight of birds.A feather comprises a rachis and two rows of barbs on each side of the rachis[1,2].Each side of the barbs features a row of barbules.In extant flying birds,the ventral side of the distal half of the distal barbule bears several hook-like structures called hooklets,while the dorsal side of the proximal barbule curves into a narrow groove,creating a specialized interlocking hook-and-groove mechanism that resists tearing force from the air during flight[[2],[3],[4]].
