1. The Developmental Theory of Feather Evolution By Jesse Seale

2. Feathers are complex hierarchal structures with multiple interacting parts necessary for function (for example: interlocking barbules and asymmetrical rachis in flight feathers)

3. Because feathers are novel structures we see no evidence of their evolutionary history in other animals Because feathers are so well adapted we see no evidence of their evolutionary history in extant birds ( all primitive forms are secondarily derived) Archaeopteryx shows advanced asymmetrical flight feathers

5. Since a feathers function relies on its complex structure how did it get there? What where its primitive forms? How can we know this?

6. Developmental evolution seeks to reconstruct evolutionary history from observable developmental pathways. Prum and Brush in 2002 used this theory to construct an evolutionary model for feather evolution. Theory is supported by paleontological evidence and morphological evidance. Sound criticism of fossil evidence. But, it is the most logical theory so far

7. Feather Morphogenesis