|How are birds related?
This is not just an academic question.
Every living thing is the end-product of an evolutionary history and
carries the evidence of that descent.
Until recently there were only two ways to reconstruct this history:
from the fossil record and from the constitution and distribution of living things.
Now there is a third: the comparative studies of DNA and its byproducts, which
form the basis of the work of Charles Sibley and his collaborators.
Based on DNA hybridization comparisons
by Charles G. Sibley - Burt L. Monroe, Jr.