Jinguofortis perplexus Wang, Stidham & Zhou, 2018 (artwork by Chung-Tat Cheung) |
Significance
We report the second most basal clade of the short-tailed birds (Pygostylia) from the Early Cretaceous. The new family Jinguofortisidae exhibits a mosaic assembly of plesiomorphic nonavian theropod characteristics, particularly of the fused scapulocoracoid and more derived flight-related features, further increasing the known ecomorphological diversity of basal avian lineages. We discuss the evolution of the scapula and coracoid in major tetrapod groups and early birds and hypothesize that the fused scapulocoracoid in some basal avian lineages, although rare, results from an accelerated rate of ossification and that the avian shoulder girdle likely was transformed by developmental plasticity along an evolutionary lineage leading to the crown group of birds.
Abstract
Early members of the clade Pygostylia (birds with a short tail ending in a compound bone termed “pygostyle”) are critical for understanding how the modern avian bauplan evolved from long-tailed basal birds like Archaeopteryx. However, the currently limited known diversity of early branching pygostylians obscures our understanding of this major transition in avian evolution. Here, we describe a basal pygostylian, Jinguofortis perplexus gen. et sp. nov., from the Early Cretaceous of China that adds important information about early members of the short-tailed bird group. Phylogenetic analysis recovers a clade (Jinguofortisidae fam. nov.) uniting Jinguofortis and the enigmatic basal avian taxon Chongmingia that represents the second earliest diverging group of the Pygostylia. Jinguofortisids preserve a mosaic combination of plesiomorphic nonavian theropod features such as a fused scapulocoracoid (a major component of the flight apparatus) and more derived flight-related morphologies including the earliest evidence of reduction in manual digits among birds. The presence of a fused scapulocoracoid in adult individuals independently evolved in Jinguofortisidae and Confuciusornithiformes may relate to an accelerated osteogenesis during chondrogenesis and likely formed through the heterochronic process of peramorphosis by which these basal taxa retain the scapulocoracoid of the nonavian theropod ancestors with the addition of flight-related modifications. With wings having a low aspect ratio and wing loading, Jinguofortis may have been adapted particularly to dense forest environments. The discovery of Jinguofortis increases the known ecomorphological diversity of basal pygostylians and highlights the importance of developmental plasticity for understanding mosaic evolution in early birds.
Keywords: bird, development, Mesozoic, plasticity, phylogeny
Jinguofortis perplexus gen. et sp. nov., IVPP V24194. Photographs of counter slab and main slab. |
Systematic Paleontology
Aves Linnaeus, 1758
Pygostylia Chiappe, 2002
Jinguofortisidae fam. nov.
Jinguofortis perplexus gen. et sp. nov.
Holotype: A complete and articulated skeleton with feathers is housed at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) under the collect number IVPP V24194 (Fig. 1 and SI Appendix, Figs. S1–S7 and Table S1).
Etymology: The generic name is derived from “jinguo” (Mandarin), referring to female warrior, and “fortis”, Latin for brave; the specific name is derived from Latin “perplexus,” referring to the combination of plesiomorphic and derived characters present in the holotype specimen.
Locality and Horizon: IVPP V24194 was collected near the village of Shixia, Weichang County, Hebei Province, China; Lower Cretaceous Dabeigou Formation of the Jehol Biota (127 ± 1.1 Ma).
Reconstruction of Jinguofortis perplexus, second earliest member of the short-tailed birds Pygostylia (artwork by Chung-Tat Cheung) |
Min Wang, Thomas A. Stidham and Zhonghe Zhou. 2018. A New Clade of Basal Early Cretaceous Pygostylian Birds and Developmental Plasticity of the Avian Shoulder Girdle. PNAS. DOI: 10.1073/pnas.1812176115
Min Wang, Xiaoli Wang, Yan Wang and Zhonghe Zhou. 2016. A New Basal Bird from China with implications for Morphological Diversity in Early Birds. Scientific Reports. 6: 19700. DOI: 10.1038/srep19700
Chinese Cretaceous fossil highlights avian evolution eurekalert.org/e/8pkg via @EurekAlert
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روابط التحميل والمشاهدة، الروابط المباشرة للتحميل
او
شاهد هذا الفيديو القصير لطريقة التحميل البسيطة
كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا
شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا
رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا
تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا
ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.
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