Digital restoration of the pectoral girdles of two Early Cretaceous birds and implications for early-flight evolution
The morphology of the pectoral girdle, the skeletal structure connecting the wing to the body, is a key determinant of flight capability, but in some respects is poorly known among stem birds. Here, the pectoral girdles of the Early Cretaceous birds Sapeornis and Piscivorenantiornis are reconstructe...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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eLife Sciences Publications Ltd
2022-03-01
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| Series: | eLife |
| Subjects: | |
| Online Access: | https://elifesciences.org/articles/76086 |
| _version_ | 1797998217937289216 |
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| author | Shiying Wang Yubo Ma Qian Wu Min Wang Dongyu Hu Corwin Sullivan Xing Xu |
| author_facet | Shiying Wang Yubo Ma Qian Wu Min Wang Dongyu Hu Corwin Sullivan Xing Xu |
| author_sort | Shiying Wang |
| collection | DOAJ |
| description | The morphology of the pectoral girdle, the skeletal structure connecting the wing to the body, is a key determinant of flight capability, but in some respects is poorly known among stem birds. Here, the pectoral girdles of the Early Cretaceous birds Sapeornis and Piscivorenantiornis are reconstructed for the first time based on computed tomography and three-dimensional visualization, revealing key morphological details that are important for our understanding of early-flight evolution. Sapeornis exhibits a double articulation system (widely present in non-enantiornithine pennaraptoran theropods including crown birds), which involves, alongside the main scapula-coracoid joint, a small subsidiary joint, though variation exists with respect to the shape and size of the main and subsidiary articular contacts in non-enantiornithine pennaraptorans. This double articulation system contrasts with Piscivorenantiornis in which a spatially restricted scapula-coracoid joint is formed by a single set of opposing articular surfaces, a feature also present in other members of Enantiornithines, a major clade of stem birds known only from the Cretaceous. The unique single articulation system may reflect correspondingly unique flight behavior in enantiornithine birds, but this hypothesis requires further investigation from a functional perspective. Our renderings indicate that both Sapeornis and Piscivorenantiornis had a partially closed triosseal canal (a passage for muscle tendon that plays a key role in raising the wing), and our study suggests that this type of triosseal canal occurred in all known non-euornithine birds except Archaeopteryx, representing a transitional stage in flight apparatus evolution before the appearance of a fully closed bony triosseal canal as in modern birds. Our study reveals additional lineage-specific variations in pectoral girdle anatomy, as well as significant modification of the pectoral girdle along the line to crown birds. These modifications produced diverse pectoral girdle morphologies among Mesozoic birds, which allowed a commensurate range of capability levels and styles to emerge during the early evolution of flight. |
| first_indexed | 2024-04-11T10:45:08Z |
| format | Article |
| id | doaj.art-0d9c952c36ed43828bfc8361161e7f8b |
| institution | Directory Open Access Journal |
| issn | 2050-084X |
| language | English |
| last_indexed | 2024-04-11T10:45:08Z |
| publishDate | 2022-03-01 |
| publisher | eLife Sciences Publications Ltd |
| record_format | Article |
| series | eLife |
| spelling | doaj.art-0d9c952c36ed43828bfc8361161e7f8b2022-12-22T04:29:04ZengeLife Sciences Publications LtdeLife2050-084X2022-03-011110.7554/eLife.76086Digital restoration of the pectoral girdles of two Early Cretaceous birds and implications for early-flight evolutionShiying Wang0https://orcid.org/0000-0001-6067-0303Yubo Ma1Qian Wu2Min Wang3https://orcid.org/0000-0001-8506-1213Dongyu Hu4Corwin Sullivan5Xing Xu6https://orcid.org/0000-0002-4786-9948Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing, China; University of Chinese Academy of Sciences, Beijing, ChinaUniversity of Alberta, Edmonton, CanadaKey Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing, China; University of Chinese Academy of Sciences, Beijing, ChinaKey Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing, ChinaShenyang Normal University, Shenyang, ChinaUniversity of Alberta, Edmonton, Canada; Philip J. Currie Dinosaur Museum, Wembley, CanadaKey Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing, China; Shenyang Normal University, Shenyang, China; Centre for Vertebrate Evolutionary Biology, Yunnan University, Kunming, ChinaThe morphology of the pectoral girdle, the skeletal structure connecting the wing to the body, is a key determinant of flight capability, but in some respects is poorly known among stem birds. Here, the pectoral girdles of the Early Cretaceous birds Sapeornis and Piscivorenantiornis are reconstructed for the first time based on computed tomography and three-dimensional visualization, revealing key morphological details that are important for our understanding of early-flight evolution. Sapeornis exhibits a double articulation system (widely present in non-enantiornithine pennaraptoran theropods including crown birds), which involves, alongside the main scapula-coracoid joint, a small subsidiary joint, though variation exists with respect to the shape and size of the main and subsidiary articular contacts in non-enantiornithine pennaraptorans. This double articulation system contrasts with Piscivorenantiornis in which a spatially restricted scapula-coracoid joint is formed by a single set of opposing articular surfaces, a feature also present in other members of Enantiornithines, a major clade of stem birds known only from the Cretaceous. The unique single articulation system may reflect correspondingly unique flight behavior in enantiornithine birds, but this hypothesis requires further investigation from a functional perspective. Our renderings indicate that both Sapeornis and Piscivorenantiornis had a partially closed triosseal canal (a passage for muscle tendon that plays a key role in raising the wing), and our study suggests that this type of triosseal canal occurred in all known non-euornithine birds except Archaeopteryx, representing a transitional stage in flight apparatus evolution before the appearance of a fully closed bony triosseal canal as in modern birds. Our study reveals additional lineage-specific variations in pectoral girdle anatomy, as well as significant modification of the pectoral girdle along the line to crown birds. These modifications produced diverse pectoral girdle morphologies among Mesozoic birds, which allowed a commensurate range of capability levels and styles to emerge during the early evolution of flight.https://elifesciences.org/articles/76086Early Cretaceousstem birdspectoral girdlescapula-coracoid articulationtriosseal canal |
| spellingShingle | Shiying Wang Yubo Ma Qian Wu Min Wang Dongyu Hu Corwin Sullivan Xing Xu Digital restoration of the pectoral girdles of two Early Cretaceous birds and implications for early-flight evolution eLife Early Cretaceous stem birds pectoral girdle scapula-coracoid articulation triosseal canal |
| title | Digital restoration of the pectoral girdles of two Early Cretaceous birds and implications for early-flight evolution |
| title_full | Digital restoration of the pectoral girdles of two Early Cretaceous birds and implications for early-flight evolution |
| title_fullStr | Digital restoration of the pectoral girdles of two Early Cretaceous birds and implications for early-flight evolution |
| title_full_unstemmed | Digital restoration of the pectoral girdles of two Early Cretaceous birds and implications for early-flight evolution |
| title_short | Digital restoration of the pectoral girdles of two Early Cretaceous birds and implications for early-flight evolution |
| title_sort | digital restoration of the pectoral girdles of two early cretaceous birds and implications for early flight evolution |
| topic | Early Cretaceous stem birds pectoral girdle scapula-coracoid articulation triosseal canal |
| url | https://elifesciences.org/articles/76086 |
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