Abstract
The concept of ichnodisparity is herein introduced for the study of fossil vertebrates, using Gondwanan avian footprints. We define ichnodisparity for trackways as the qualitative variation in morphological patterns of autopodial impressions, most likely reflecting functional or ecological thresholds. Foot architectural designs are defined based on anatomical features, including digit number and orientation and interdigital webbing, and size. Ichnodisparity in fossil bird tracks is proposed here as a useful proxy for analyzing evolutionary radiations and characterizing macroevolutionary patterns. Twenty-three geological formations from Gondwana were analyzed, spanning from the Early Cretaceous to the Late Pleistocene. The earliest morphotypes were predominantly large-sized, while small morphotypes became dominant over time. No zygodactyl footprints are recorded from Gondwana. Prior to the K/Pg boundary, ichnodisparity was high, consistent with a Cretaceous avian radiation. During the Eocene, morphological variety remained comparable to that of the Late Cretaceous — except for the large tridactyl design — suggesting ecological turnover rather than functional expansion; elevated ichnodisparity may be associated with the Early Eocene Climatic Optimum. The decline recorded in the Oligocene is likely attributable to sampling bias. The Miocene concentrates the highest ichnodisparity in the fossil record, with the reappearance of large pedal architectures linked to cursorial birds, supporting an expansion into open spaces. In the Pleistocene, small tridactyl forms disappeared and the large palmate architecture emerged for the first time, indicating a new episode of ecological turnover.
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Acknowledgements
We thank Silvina de Valais and an anonymous reviewer for their thorough and constructive comments, which substantially improved the manuscript. We also thank Sebastian Richiano for his careful and meticulous editorial work. This is MF, VK and CAM contribution R-555 to the IDEAN-CONICET.
Funding
This research was supported by PICT-2020-2635 and CONICET-BAYLAT 2021–2022 and Alexander von Humboldt Foundation “Georg Forster Research Fellowship for Experienced Researchers” to VK. We also thank funding from the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grants 311727-26 and 422931-25 awarded to MGM and LAB, respectively. Mángano recognizes additional funding from the George J. McLeod Enhancement Chair in Geology.
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Farina, M.E., Mángano, M.G., Buatois, L.A. et al. Macroevolutionary trends of avian ichnodisparity in Gondwana.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-56695-z
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DOI: https://doi.org/10.1038/s41598-026-56695-z
Keywords
- Trace fossils
- Pedal architecture
- Bird evolution
- Ecological turnover
- Cenozoic
Source: Ecology - nature.com
