The evolution of the pectoral extrinsic appendicular and infrahyoid musculature in theropods and its functional and behavioral importance

Klingler, Jeremy

doi:10.1111/joa.13256

Cited by 4 publications

(2 citation statements)

References 57 publications

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“…Both Sapeornis and enantiornithines have features of the pectoral girdle (e.g., dorsolaterally projecting acrocoracoid process in Sapeornis , and elongate acromion process and widely spaced acrocoracoid processes in enantiornithines) that imply the lack of a coracoid-furcula contact ( Mayr, 2017 ; Novas et al, 2021 ). Absence of such a contact is a plesiomorphic feature, widely observed among non-avialan theropods ( Currie and Zhiming, 2001 ; Klingler, 2020 ; Lü, 2003 ). Thus, Sapeornis and enantiornithines have only a partially enclosed bony triosseal canal, though a ligament could have completed the enclosure of the canal as in some modern birds ( Ghetie, 1976 ).…”

Section: Discussionmentioning

confidence: 95%

Digital restoration of the pectoral girdles of two Early Cretaceous birds and implications for early-flight evolution

Wang

et al. 2022

eLife

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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 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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Section: Discussionmentioning

confidence: 95%

Digital restoration of the pectoral girdles of two Early Cretaceous birds and implications for early-flight evolution

Wang

et al. 2022

eLife

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“…Both Sapeornis and enantiornithines have features of the pectoral girdle (e.g., dorsolaterally projecting acrocoracoid process in Sapeornis, and elongate acromion process and widely spaced tips of the coracoids in enantiornithines) implying the lack of a coracoid-furcula contact (Mayr, 2017;Novas et al, 2021). Absence of such a contact is a plesiomorphic feature, widely observed among non-avialan theropods (Currie and Dong, 2001;Klingler, 2020;Lü, 2003). Thus, Sapeornis and enantiornithines have only a partially enclosed bony triosseal canal, though a ligament could have completed the enclosure of the canal as in some modern birds (Ghetie, 1976).…”

Section: Our Reconstructions Of the Pectoral Girdles Of Sapeornis And Piscivorenantiornismentioning

confidence: 99%

Digital restoration of the pectoral girdles of two Early Cretaceous birds, and implications for early flight evolution

Wang

et al. 2021

Preprint

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Pectoral girdle morphology is a key determinant of flight capability, but in some respects is poorly known among stem birds. Here, we reconstruct the pectoral girdles of the Early Cretaceous birds Sapeornis and Piscivorenantiornis based on computed tomography and three-dimensional visualization, revealing key morphological details. Enantiornithines such as Piscivorenantiornis have a uniquely localized scapula-coracoid joint, with only one area of articulation. This single articulation contrasts with the double articulation widely present in non-enantiornithine pennaraptoran theropods, including Sapeornis and crown birds, which comprises main and subsidiary articular contacts. A partially closed triosseal canal occurs in non-euornithine birds, representing a transitional stage in flight apparatus evolution. Numerous modifications of the pectoral girdle along the line to crown birds, and lineage-specific pectoral girdle variations, produced diverse pectoral girdle morphologies among Mesozoic birds, which ensured that a commensurate range of capability levels and modes emerged during the early evolution of flight.

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Appendicular myology of Skorpiovenator bustingorryi: A first attempt to reconstruct pelvic and hindlimb musculature in an abelisaurid theropod

Cerroni,

Otero,

Novas

2024

The Anatomical Record

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We present the pelvic and hindlimb musculature of the abelisaurid Skorpiovenator bustingorryi, constituting the most comprehensive muscle reconstruction to date in ceratosaur theropods. Using extant phylogenetic bracket method, we reconstructed 39 muscles that can commonly found in extant archosaurs. Through the identification of bone correlates, we recognized thigh and hindlimb muscles including knee extensors, m. iliofibularis, m. flexor tibialis externus, mm. caudofemorales, mm. puboischiofemorales, and crus muscles important in foot extension and flexion (e.g., m. tibialis anterior, mm. gastrocnemii). Also, autopodial intrinsic muscles were reconstructed whose function involve extension (m. extensor digiti 2–4), flexion (mm. flexor digitorum brevis superficialis), interdigital adduction (m. interosseus dorsalis) and abduction (m. interosseous plantaris, m. abductor 4). Abelisaurids like Skorpiovenator show a deep pre‐ and postacetabular blade of the ilia and enlarged cnemial crests, which would have helped increasing the moment arm of muscles related to hip flexion and hindlimb extension. Also, pedal muscles related to pronation were probably present but reduced (e.g., m. pronator profundus). Despite some gross differences in the autopodial morphology in extant outgroups (e.g., crocodilian metatarsus and avian tarsometatarsus), the present study allows us to hypothesize several pedal muscles in Skorpiovenator. These muscles would not be arranged in tendinous bundles as in Neornithes, but rather the condition would be similar to that of crocodilians with several layers formed by fleshy bellies on the plantar and dorsal aspects of the metatarsus. The musculature of Skorpiovenator is key for future studies concerning abelisaurid biomechanics, including the integration of functional morphology and ichnological data.

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The evolution of the pectoral extrinsic appendicular and infrahyoid musculature in theropods and its functional and behavioral importance

Cited by 4 publications

References 57 publications

Digital restoration of the pectoral girdles of two Early Cretaceous birds and implications for early-flight evolution

Digital restoration of the pectoral girdles of two Early Cretaceous birds and implications for early-flight evolution

Digital restoration of the pectoral girdles of two Early Cretaceous birds, and implications for early flight evolution

Appendicular myology of Skorpiovenator bustingorryi: A first attempt to reconstruct pelvic and hindlimb musculature in an abelisaurid theropod

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