For really, really good (yet quite in-depth) discussions on bird evolution, may I suggest the EvoWiki? I suggested many pages in my thread in Links and Information :
EvC Forum: EvoWiki - Evolution Education Wiki
Although at the time of posting this, we appear to be having technical issues.
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Contributors needed for the following articles: Pleiotropy, Metabolism, Promoter, Invertebrate, Meiosis, DNA, Transcription, Chromosome, Tetrapod, Fossil, Phenotype, Messenger RNA, Mammals, Appendix , Variation, Selection, Gene, Gametogenesis, Homo erectus and others.
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