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Wang S, Ma Y, Wu Q, Wang M, Hu D, Sullivan C, Xu X. Digital restoration of the pectoral girdles of two Early Cretaceous birds, and implications for early flight evolution. eLife 2022; 11:76086. [PMID: 35356889 PMCID: PMC9023055 DOI: 10.7554/elife.76086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 03/30/2022] [Indexed: 11/30/2022] Open
Abstract
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.
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Affiliation(s)
- Shiying Wang
- Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Yubo Ma
- University of Alberta, Edmonton, Canada
| | - Qian Wu
- Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Min Wang
- Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Dongyu Hu
- Paleontological Museum of Liaoning, Shenyang Normal University, Shenyang, China
| | | | - Xing Xu
- Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
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Benito J, Chen A, Wilson LE, Bhullar BAS, Burnham D, Field DJ. Forty new specimens of Ichthyornis provide unprecedented insight into the postcranial morphology of crownward stem group birds. PeerJ 2022; 10:e13919. [PMID: 36545383 PMCID: PMC9762251 DOI: 10.7717/peerj.13919] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 07/28/2022] [Indexed: 12/23/2022] Open
Abstract
Ichthyornis has long been recognized as a pivotally important fossil taxon for understanding the latest stages of the dinosaur-bird transition, but little significant new postcranial material has been brought to light since initial descriptions of partial skeletons in the 19th Century. Here, we present new information on the postcranial morphology of Ichthyornis from 40 previously undescribed specimens, providing the most complete morphological assessment of the postcranial skeleton of Ichthyornis to date. The new material includes four partially complete skeletons and numerous well-preserved isolated elements, enabling new anatomical observations such as muscle attachments previously undescribed for Mesozoic euornitheans. Among the elements that were previously unknown or poorly represented for Ichthyornis, the new specimens include an almost-complete axial series, a hypocleideum-bearing furcula, radial carpal bones, fibulae, a complete tarsometatarsus bearing a rudimentary hypotarsus, and one of the first-known nearly complete three-dimensional sterna from a Mesozoic avialan. Several pedal phalanges are preserved, revealing a remarkably enlarged pes presumably related to foot-propelled swimming. Although diagnosable as Ichthyornis, the new specimens exhibit a substantial degree of morphological variation, some of which may relate to ontogenetic changes. Phylogenetic analyses incorporating our new data and employing alternative morphological datasets recover Ichthyornis stemward of Hesperornithes and Iaceornis, in line with some recent hypotheses regarding the topology of the crownward-most portion of the avian stem group, and we establish phylogenetically-defined clade names for relevant avialan subclades to help facilitate consistent discourse in future work. The new information provided by these specimens improves our understanding of morphological evolution among the crownward-most non-neornithine avialans immediately preceding the origin of crown group birds.
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Affiliation(s)
- Juan Benito
- Department of Biology & Biochemistry, Milner Centre for Evolution, University of Bath, Bath, United Kingdom.,Department of Earth Sciences, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom
| | - Albert Chen
- Department of Biology & Biochemistry, Milner Centre for Evolution, University of Bath, Bath, United Kingdom.,Department of Earth Sciences, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom
| | - Laura E Wilson
- Fort Hays State University, Sternberg Museum of Natural History and Department of Geosciences, Hays, Kansas, United States
| | - Bhart-Anjan S Bhullar
- Yale Peabody Museum of Natural History, New Haven, Conneticut, United States.,Department of Earth & Planetary Sciences, Yale University, New Haven, Conneticut, United States
| | - David Burnham
- University of Kansas, Biodiversity Institute and Natural History Museum, Lawrence, Kansas, United States
| | - Daniel J Field
- Department of Earth Sciences, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom.,University Museum of Zoology, Cambridge, United Kingdom
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Wang M, Zhou Z, Zhou S. Renaming of BelluliaWang, Zhou & Zhou, 2016. Zool J Linn Soc 2016. [DOI: 10.1111/zoj.12397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Min Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences; Institute of Vertebrate Paleontology and Paleoanthropology; Chinese Academy of Sciences; 142 Xizhimenwai Street Beijing 100044 China
| | - Zhonghe Zhou
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences; Institute of Vertebrate Paleontology and Paleoanthropology; Chinese Academy of Sciences; 142 Xizhimenwai Street Beijing 100044 China
| | - Shuang Zhou
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences; Institute of Vertebrate Paleontology and Paleoanthropology; Chinese Academy of Sciences; 142 Xizhimenwai Street Beijing 100044 China
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Wang M, Lloyd GT. Rates of morphological evolution are heterogeneous in Early Cretaceous birds. Proc Biol Sci 2016; 283:20160214. [PMID: 27053742 PMCID: PMC4843658 DOI: 10.1098/rspb.2016.0214] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 03/10/2016] [Indexed: 11/12/2022] Open
Abstract
The Early Cretaceous is a critical interval in the early history of birds. Exceptional fossils indicate that important evolutionary novelties such as a pygostyle and a keeled sternum had already arisen in Early Cretaceous taxa, bridging much of the morphological gap between Archaeopteryx and crown birds. However, detailed features of basal bird evolution remain obscure because of both the small sample of fossil taxa previously considered and a lack of quantitative studies assessing rates of morphological evolution. Here we apply a recently available phylogenetic method and associated sensitivity tests to a large data matrix of morphological characters to quantify rates of morphological evolution in Early Cretaceous birds. Our results reveal that although rates were highly heterogeneous between different Early Cretaceous avian lineages, consistent patterns of significantly high or low rates were harder to pinpoint. Nevertheless, evidence for accelerated evolutionary rates is strongest at the point when Ornithuromorpha (the clade comprises all extant birds and descendants from their most recent common ancestors) split from Enantiornithes (a diverse clade that went extinct at the end-Cretaceous), consistent with the hypothesis that this key split opened up new niches and ultimately led to greater diversity for these two dominant clades of Mesozoic birds.
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Affiliation(s)
- Min Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xizhimenwai Street, Beijing 100044, People's Republic of China
| | - Graeme T Lloyd
- Department of Biological Sciences, Faculty of Science, Macquarie University, Sydney, New South Wales 2109, Australia
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