However, in today's "Nature" an even more detailed study appears (by Prum et al), which changes things dramatically. Here is a comparison of the 2 evolutionary trees, Prum on the left and Jarvis on the right.
Amazingly, according to the new study, the hummingbird group branched off from all other extant bird groups right from the start! Thus they appear on their own at the top of the Prum tree. The other group of birds gave rise to all other living bird species!
However, the Prum and Jarvis trees differ greatly. Which is right? Prum et al argue that the earliest roots of the tree are tangled (see the way some of the red and blue lines cross each other) and under these conditions one needs a lot of data (genomes of a lot of current species) to correctly untangle the longest twistiest roots without breakage (a problem every gardener knows well).
The reason for this appears to be that almost all primitive bird groups died out at the K-T transition, the massive meteor event, 65 million years ago, that wiped out the dinosaurs, and also triggered massive diversification of primitive mammals (an event without which you would not be reading this).
The world recovered quite rapidly (on a geological time scale) from this catastrophe, and the few remaining bird groups then underwent a rapid explosion of diversification. Was the fact that a few protomammals and protobirds survived while dinosaurs did not, mere chance, part of God's plan, or because these groups could more quickly adapt to the new conditions? More to follow.......
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