See:
http://www.abc.net.au/science/articles/2011/04/05/3181871.htm
Article reads: White and colleagues compared six genes from 16 of the 21 different species of cockatoos we see today. The amount of DNA sequenced allowed the researchers to not only draw up a family tree, but to use DNA mutations to date when different groups of cockatoos evolved. Their research found that cockatoos and parrots branched away from each other around 40 million years ago.
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