Talk Origins Archive
Talk Origins: All About Archaeopteryx
Good site which appears to take an unbiased approach to examining the wealth of evidence about the origins of birds. Provides tons of information about specimens, features, feather development, and more.
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University of Bristol: The Evolution of Birds
A short but effective synopsis providing much of the information collected over the years in terms of deciding the evolutionary ancestry issue. Article takes the pro-dinosaurian stance in the end, but includes good, if not brief,...