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Microstructural and crystallographic evolution of palaeognath (Aves) eggshells
Seung Choi1,2, Mark E Hauber3, Lucas J Legendre4
1Department of Earth Sciences, Montana State University, Bozeman, United States.
Elife
|January 31, 2023
Summary
Recent genome-wide analyses reveal dinosaur eggshell evolution. Rhea-style eggshells are homologous and ancestral, while ostrich- and tinamou-styles are homoplastic, offering insights into avian and dinosaur evolution.
Area of Science:
- Paleontology
- Avian Biology
- Materials Science
Background:
- Recent advances in genome-wide comparative analyses have significantly revised avian palaeognath phylogeny.
- This provides a novel opportunity to investigate the evolutionary history of microstructure and crystallography in modern dinosaur eggshells.
Purpose of the Study:
- To analyze the microstructural and crystallographic evolution of palaeognath eggshells.
- To determine the homology and ancestral state of different palaeognath eggshell morphotypes.
Main Methods:
- Electron backscatter diffraction was used to analyze eggshells from major Palaeognathae clades (including extinct taxa).
- Eggshells from Neognathae and non-avian dinosaurs were included for comparative analysis.
- Ancestral state reconstruction and parsimony analysis were employed.
Main Results:
- Detailed microstructures and crystallographies of ostrich-, rhea-, and tinamou-style morphotypes were elucidated.
- Rhea-style eggshells were found to be homologous, representing the ancestral state.
- Ostrich- and tinamou-style morphotypes were identified as homoplastic, acquired independently.
Conclusions:
- Rhea-style eggshell represents the ancestral condition for both microstructure and crystallography in palaeognaths.
- The findings enhance understanding of modern and extinct dinosaur eggshell evolution.
- Palaeognath eggshells serve as valuable archives for diverse fields like palaeoenvironmental reconstructions and zooarchaeology.
