Tuesday, November 07, 2006

Additional Novarchosaurian Detail

I realized that there were a couple details about the Novarchosaurians that I had been leaving out that makes them rather distinct from birds. After all, despite the changes I had talked about already for various Novarchosaurians, there's not much difference in the descriptions than from birds. So far, three distinctions have either been the odd forms of feet that birds, as yet have not evolved, the recovered arms, or more properly the 100% lack of wings (either replaced by regression to arms or completely by complete removal of even the bones).

The first change is that the keel on the sternum of the novarchosaurians has gone positively ratite. Since these are nonfliers, that is no longer needed. That's a distinction that wouldn't make much difference to most people. You would hardly notice. if at all.

The biggest difference is one you cannot help noticing. They have a tail. Not merely a bird tail of feathers and a little stub of flesh, but a full grown, nearly dinosaurian tail. It has two functions. The first is to act for balance. Some of the novarchosaurians have very long necks that are quite heavy. This balances out the weight for these bipeds (since all of them are bipeds). Secondly, this is where they store their fat for the long dark winters.

Yes, they're still feathered though. :)

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