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Chicken Recombinant Limbs Assay to Understand Morphogenesis, Patterning, and Early Steps in Cell Differentiation
Published on: January 12, 2022
Contrasting developmental trajectories in the earliest known tetrapod forelimbs
Viviane Callier1, Jennifer A Clack, Per E Ahlberg
1University Museum of Zoology Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
Science (New York, N.Y.)
|April 18, 2009
Summary
Early tetrapods Ichthyostega and Acanthostega show distinct limb development. Ichthyostega
Area of Science:
- Paleontology
- Evolutionary Biology
- Comparative Anatomy
Background:
- Ichthyostega and Acanthostega are key early tetrapods.
- Acanthostega is typically viewed as more primitive.
- Understanding their limb development offers insights into tetrapod evolution.
Purpose of the Study:
- To investigate ontogenetic trajectories of forelimb development in Ichthyostega and Acanthostega.
- To compare muscle attachment patterns on humeri between these early tetrapods and stem tetrapods.
- To infer differences in terrestrial locomotion and phylogenetic relationships.
Main Methods:
- Analysis of new skeletal material from Ichthyostega and Acanthostega.
- Comparative examination of muscle attachment sites on humeri across different ontogenetic stages.
- Phylogenetic analysis incorporating newly identified primitive characteristics.
Main Results:
- Ichthyostega humeri show a developmental shift from fish-like to tetrapod-like muscle attachment patterns.
- Acanthostega humeri consistently display tetrapod-like muscle attachment patterns throughout development.
- Newly identified primitive traits suggest Ichthyostega may be phylogenetically more basal than Acanthostega.
Conclusions:
- Ichthyostega likely exhibited greater locomotor terrestrialization during its development.
- The phylogenetic position of Ichthyostega may need re-evaluation, potentially being more basal than previously thought.
- Ontogenetic data provides crucial evidence for understanding early tetrapod evolution and terrestrial adaptation.
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