@article{f09eef0641ba414abc07d46f58d29942,
title = "Variations of Mesozoic feathers: Insights from the morphogenesis of extant feather rachises",
abstract = "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.",
keywords = "Burmese amber, contour feather, developmental constraint, evo-devo, Late Cretaceous",
author = "Shuo Wang and Chang, {Wei Ling} and Qiyue Zhang and Menglu Ma and Feng Yang and De Zhuo and Hans, {Harn I.Chen} and Rui Yang and Ping Wu and Michael Habib and Juan, {Wen Tau} and Chuong, {Cheng Ming}",
note = "Funding Information: We wish to thank the editors and two anonymous reviews for their constrictive critiques and advices improving the manuscript. SW is supported by the Human Frontier Sciences Project (LT000728/2018); PW and C‐MC are supported by the National Institutes of Health, USA (AR47364, AR60306) and a research contract between China Medical University (CMU)/ Hospital in Taiwan and USC (USC grant number 5351285884). C‐MC is a paid scientific advisor of CMU/ hospital. W‐LC and W‐TJ are supported by the Integrative Stem Cell Center, CMU/ Hospital in Taiwan, grants from Taiwan Higher Education Sprout Project by the Ministry of Education in Taiwan, and grants from Ministry of Science and Technology in Taiwan. We thank D. Ren and T. Gao (CNU) for proving important samples and helping photography, A. Li, P. Zhang, H. Zhang (Capital Normal University) and H. Mao (Peking University) for discussing the functional simulation results, and R. Widelitz for improving the manuscript. Funding Information: We wish to thank the editors and two anonymous reviews for their constrictive critiques and advices improving the manuscript. SW is supported by the Human Frontier Sciences Project (LT000728/2018); PW and C-MC are supported by the National Institutes of Health, USA (AR47364, AR60306) and a research contract between China Medical University (CMU)/ Hospital in Taiwan and USC (USC grant number 5351285884). C-MC is a paid scientific advisor of CMU/ hospital. W-LC and W-TJ are supported by the Integrative Stem Cell Center, CMU/ Hospital in Taiwan, grants from Taiwan Higher Education Sprout Project by the Ministry of Education in Taiwan, and grants from Ministry of Science and Technology in Taiwan. We thank D. Ren and T. Gao (CNU) for proving important samples and helping photography, A. Li, P. Zhang, H. Zhang (Capital Normal University) and H. Mao (Peking University) for discussing the functional simulation results, and R. Widelitz for improving the manuscript. Publisher Copyright: {\textcopyright} 2020 The Authors. Evolution {\textcopyright} 2020 The Society for the Study of Evolution.",
year = "2020",
month = sep,
day = "1",
doi = "10.1111/evo.14051",
language = "English",
volume = "74",
pages = "2121--2133",
journal = "Evolution",
issn = "0014-3820",
publisher = "Oxford University Press",
number = "9",
}