Evaluating variation in Solnhofen avialans
Open accessAbstract
As the oldest known fossil bird, Archaeopteryx is pivotal to the study of avian origins. Fifteen avialan fossils have been described from the Upper Jurassic Solnhofen Limestones, 14 of which have been referred to Archaeopteryx. Recently, this sample has been hypothesized to include archaeopterygids, non-archaeopterygid avians and anchiornithines, although interpretations concerning newly erected non-archaeopterygid avialans have not been critically examined, and currently, there is no taxonomic consensus. Morphometrics, as a powerful tool for understanding variation within a sample, can recognize non-random patterns that can support taxonomic hypotheses. Here, we analyse linear skeletal measurements from all Solnhofen avialans and compare them to the non-avian avialan Anchiornis. Results strongly suggest all Solnhofen avialans belong to a single taxon conforming to a growth curve. If more than one taxon is represented within the sample, these taxa are proportionately indistinguishable when growth is considered. Results also indicate that, while the forelimb becomes proportionately longer with increasing maturity, the opposite pattern is observed in Anchiornis, supporting interpretations that anchiornithines are non-volant. We examine the validity of the genera Ostromia and Alcmonavis and argue that purported diagnostic features do not provide robust support for their distinctiveness. Our results suggest that all known Solnhofen avialans represent Archaeopteryx.
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Anchiornis was non-volant.
“it is increasingly clear from the morphology of the skeleton, forelimb feathers, molt pattern, and ontogenetic changes in proportions that this taxon was non-volant [2, 4-6]”
From The ecology of Archaeopteryx (2026) · cites this paper as [6]
Lower variation in proportions observed in flying birds may be related to aerodynamic constraints for optimal flight proportions.
“This lower variation observed in flying birds may be related to aerodynamic constraints for the optimal proportions required for flight [6].”
From The ecology of Archaeopteryx (2026) · cites this paper as [6]
Morphometric analysis of skeletal measurements supports flight ability in Archaeopteryx and its absence in Anchiornis.
“Morphometric analysis of Archaeopteryx skeletal measurements, compared to Anchiornis , also supports flight ability in Archaeopteryx , and conversely, its absence in Anchiornis .”
From The ecology of Archaeopteryx (2026) · cites this paper as [6]
In larger specimens of Archaeopteryx, the forelimb becomes proportionately longer, a trend also seen in Confuciusornis, whereas in Anchiornis the hindlimb is longer in larger individuals.
“In larger specimens of Archaeopteryx (e.g., Solnhofen, London), the forelimb becomes proportionately longer, a trend also observed in Confuciusornis , whereas in Anchiornis the hindlimb is longer in larger individuals [6, 53].”
From The ecology of Archaeopteryx (2026) · cites this paper as [6]
Archaeopteryx skeletal measurements fit a tight regression, as in Confuciusornis, whereas Anchiornis specimens show greater variation in proportions.
“Archaeopteryx skeletal measurements also fit a tight regression [54, 55], as observed in Confuciusornis , whereas Anchiornis specimens do not plot close to the regression line indicating greater variation in proportions [6, 56].”
From The ecology of Archaeopteryx (2026) · cites this paper as [6]
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New specimen of Archaeopteryx provides insights into the evolution of pennaceous feathers
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Potential for Powered Flight Neared by Most Close Avialan Relatives, but Few Crossed Its Thresholds
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O’Connor, J. K., & Clark, A. D. (2026) · Discover Ecology · doi:10.1007/s44396-026-00026-z
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- Authors
- O’Connor, J., & Marugán-Lobón, J.
- Affiliations
- Field Museum of Natural History 1 , , ,
- Universidad Autonoma de Madrid 2 , ,
- ORCID
- O’Connor, Jingmai
- Venue
- Biology Letters
- Publisher
- The Royal Society
- Published
- 2026-03-25
- Volume
- 22
- Issue
- 3
- ISSN
- 1744-9561 (ISSN-L)
- 1744-957X
- OpenAlex
- W7140198582
- Cited by
- 3
- References
- 13
- Citations by year
- 2026: 3
- FWCI
- 11.93
- Type
- journal article
- Language
- en
- Open access
- diamond
- doi.org
- Licence
- Locations
- Biology Letters (publishedVersion, cc-by)
- PubMed (publishedVersion)
- Topics
- Physical Sciences › Earth and Planetary Sciences › Paleontology › Paleontology and Evolutionary Biology
- Physical Sciences › Earth and Planetary Sciences › Paleontology › Evolution and Paleontology Studies
- Life Sciences › Agricultural and Biological Sciences › Ecology, Evolution, Behavior and Systematics › Fossil Insects in Amber
- Keywords
- Archaeopteryx, Solnhofen limestone, Late Jurassic, avian origin, morphometrics, skeletal measurements, growth curves, taxonomic validity, forelimb length, fossil birds
- MeSH terms
- Animals, Birds, Fossils
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