The evolution of the avian shoulder joint
Open accessAbstract
The concavoconvex glenoid and bulbous humeral head of modern birds represent both structurally and functionally a hemisellar (half saddle) joint modified from a pattern common among post-Paleozoic tetrapods. Birds share with crocodilians, their nearest living relatives, similarities in joint architecture, including scapulohumeral and coracohumeral ligaments. The glenoid underwent a major reorientation during the evolution of the avian shoulder from the primitive condition of being posteroventrally directed as in Deinonychus antirrhopus and coelurosaurs generally to being dorsolaterally directed as in modern forms. The laterally facing glenoid of Archaeopteryx lithographica was intermediate in orientation and provided for a substantial degree of wing elevation but not the fully abducted, sagittal positioning that modern birds employ at the upstroke-downstroke transition.
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The lateral orientation of the glenoid in Archaeopteryx indicates a more restricted range of motion than in more derived birds, limiting the thrust generated by the flight stroke.
“However, the lateral orientation of the glenoid indicates a more restricted range of motion compared to more derived birds limiting the thrust generated by the flight stroke.”
From The ecology of Archaeopteryx (2026) · cites this paper as [26]
Archaeopteryx had limited flight abilities, as indicated by pectoral girdle morphology including the absence of an ossified sternum.
“Consistent with its basal position, there is ample evidence from the morphology of the pectoral girdle, including the absence of an ossified sternum, that indicates flight abilities were limited.”
From The ecology of Archaeopteryx (2026) · cites this paper as [26]
The pectoral girdle of Archaeopteryx is characterized by a wide boomerang-shaped furcula and a fused, axe-shaped scapulocoracoid with a laterally oriented glenoid.
“The pectoral girdle is characterized by a wide boomerang shaped furcula and a fused and axe-shaped scapulocoracoid with a laterally oriented glenoid [26, 27].”
From The ecology of Archaeopteryx (2026) · cites this paper as [26]
Dorsal movement of the forelimb in Archaeopteryx was relatively limited compared to ornithuromorphs, potentially indicating an emphasis on gliding after short bouts of dorsally restricted wingbeats.
“Compared to the dorsally-oriented glenoid in ornithuromorphs, which allows the wing to be fully elevated above the body for a long and powerful downward phase of the flight stroke, dorsal movement of the forelimb in Archaeopteryx would have been relatively limited, potentially indicating an emphasis on gliding after short bouts of relatively dorsally-restricted wingbeats [26].”
From The ecology of Archaeopteryx (2026) · cites this paper as [26]
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- Authors
- Jenkins, F. A.
- Corresponding author
- Jenkins, F. A.
- Venue
- American Journal of Science
- Publisher
- American Journal of Science (AJS)
- Published
- 1993-01-01
- Volume
- 293
- Issue
- A
- Pages
- 253-267
- ISSN
- 0002-9599 (ISSN-L)
- OpenAlex
- W2318463122
- Cited by
- 99
- References
- 0
- Citations by year
- 2026: 4 · 2025: 5 · 2024: 1 · 2023: 2 · 2022: 4 · 2021: 4 · 2020: 2 · 2019: 1 · 2018: 4 · 2017: 9 · 2016: 2 · 2015: 4 · 2014: 4 · 2013: 4 · 2012: 5
- FWCI
- 1.01
- Type
- journal article
- Language
- en
- Open access
- green
- nrs.harvard.edu
- Licence
- cc-by
- Locations
- American Journal of Science (publishedVersion)
- Digital Access to Scholarship at Harvard (DASH) (Harvard University) (submittedVersion, cc-by)
- Topics
- Physical Sciences › Earth and Planetary Sciences › Paleontology › Paleontology and Evolutionary Biology
- Health Sciences › Medicine › Urology › Comparative Animal Anatomy Studies
- Physical Sciences › Earth and Planetary Sciences › Paleontology › Evolution and Paleontology Studies
- Keywords
- humeral head, coracohumeral ligament, Archaeopteryx lithographica
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