Homology: A Concept in Crisis
Origins & Design 18:2

Figure 2: Common embryonic stages

Figure 2. (a) A common embryonic stage o under different conditions or in different species can directly differentiate into A or into Z. (b) Conversely, two different developmental pathways can converge into an homologous final adult morphology. [Figure after Alberch 1985]

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Copyright © 1997 Jonathan Wells and Paul Nelson. All rights reserved. International copyright secured.
File Date: 1.1.98