"One of the strangest living birds is the hoatzin, which seems to be a link with birds that became extinct millions of years ago, and even shows similarities to the first known bird Archaeopteryx... About the size of a rather slender, upright pheasant, the hoatzin has an untidy crest of feathers, blood-red eyes encircled by bright blue skin, a long neck and long tail feathers. But perhaps the most interesting characteristic is the presence of claws on the wings and these, although useless to the heavy adult bird, are employed by the youngster to clamber among the branches near the nest- just as Archaeopteryx must have done so many millions of years ago.
The main function of the wing claws, it seems, is to assist the young hoatzin in times of crisis. The nest is normally built on branches overhanging water and is thus exposed to the eyes of marauding hawks. It is a rudely constructed platform of short twigs of roughly pencil thickness. If danger threatens, the parents usually abandon the nest for the safety of dense bushes nearby. The chick, left to its own devices, either uses the wing claws to help it clamber through the branches to some inaccessible spot, or dives into the water and emerges farther downstream to clamber back to 'the nest once the danger has passed."
Here's a quick look at the critter...
Perhaps Professors Hans Larsson and Jack Horner should be studying the DNA from the hoatzin rather than that of the chicken; it looks like Mother Nature has done some of their work for them. Though, in fairness, I'm guessing that chicken eggs are generally more available for study then those of the South American, swamp-dwelling hoatzin.
Read Adrian Warren's entire, very interesting article here: RELIC OF PREHISTORY?
Update (July 27, 2011) - Here's another nice look at the modern dinobirds:
More here: Chick uses Wing-Claws to rescue itself from drowning...