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. Author manuscript; available in PMC: 2026 Mar 18.
Published in final edited form as: Dev Biol. 2025 Mar 18;522:171–195. doi: 10.1016/j.ydbio.2025.03.011

Figure 7. Temporal transition: Regulatory patterning enable a high level of adaptability.

Figure 7.

A. Regional difference and temporal difference of skin appendages in human and chicken (Chuong et al., 2012). B. Primary and Secondary feather transitions in birds. 1st row: Juvenile frigate birds show white and fluffy feathers. In the adult, the feathers transition to powerful flight and contour feathers, including red breast sacs that are used to attract a mate. 2nd row: feathers from the chicken (Chen et al., 2024; Widelitz et al., 2019). Frigate birds photo by CM Chuong. Darwin images from Wikipedia website.