Friday, July 2, 2010

Into the Details (1)

In an earlier post I had said:
It is important to realize that the result of cladistic analysis (ie. the comparison of characteristics) is completely consistent with the sequence I have been presenting.
I will elaborate on that now.
Consider the following, based on cladistic analysis:

This shows that the flying birds (eg. the Eumaniraptora) are close, in terms of characteristics to Ornithomimosauria (the flightless Cretaceous maniraptor birds).

And we also know that there is a tremendous difference, in terms of characteristics, between those birds (flying and flightless) and the dinosaurs such as the Tyrannosaurs. In fact, there is actually no reason to think that those groups are even related.

Now looking deeper at the flying birds and the flightless birds, we can conclude that the flightless birds developed from the flying birds. The cladistic analysis tells us that they were similar in characteristics. It does not tell us which developed from which. But we know from the fossil record which group came first - it was the flying birds. So the logical conclusion is that the flightless Cretaceous birds developed from the flying birds.
This by the way, is the accepted thinking concerning modern flightless birds. See here:
"Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim, and are thought to have evolved from their flying ancestors.[1])"

So we see that cladistic analysis supports the sequence that I have been presenting.

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