When Flightless Birds Ruled the Land: The Terror Birds of the New World:
http://thenaturalhistorian.com/2013/03/16/terror-birds-extreme-flightless-birds-creationism/

Size comparison of various living and extinct flightless birds. The largest ones here are all extinct including the moa, elephant bird from Madagascar, and terror birds from South and North America. Image linked from:
http://getouterspace.tumblr.com/post/25857819106/giant-birds-camelidae-and-giraffidae
Yet, somehow, other predators like the cave bear and the smilodon were ‘dealt’ with, as were mammoths - all bigger and more dangerous that the birds.
I think the idea humans becoming of ‘bird food’ is a little misplaced. Or a site hit piece. And who do you think extincted them? Nice drum sticks and large portion white meat breasts ... yum.
Back to the DNA - i think, but could be mistaken, that I saw a post on FR that questioned the African origin DNA theory. As I vaguely recall the fossilized DNA in Australian Aborigines does not lead to an African origin.