Re: K/T birds

[Daniel Bensen <dbensen@gotnet.net>]

>>or was extinction event so precise so as
> to intersect the precise division between the two taxa--that is a surgical
> strike, indeed!<<
The problem here is you are laboring under a classification (the distinction
between birds and dinosaurs) that was created after the KT extinction.  Before
the KT, there existed a wide range of dinosaur/bird-type critters.  Then, the
asteroid hit (or whatever) and a chunk of this diversity was deleted.  Through
fate or chance we are now left with the descendants of only some of  the
paleognaths and the neognaths (which the Natural History states were distinct
from each other before Tertiary).  So, no surgical strike is necessary; the
chain of events goes (wide range of diversity)---(asteroid)---(small range of
diversity=modern birds).  What is so interesting about the article is that the
only part of the range of dinosaur/birds that weren't killed were all Southern
Hemisphere.  What if the asteroid had hit Gondwana instead of Laurasia?  Our
skies would be populated with enantiorniths and we would be writing theses about
how these birds easily outcompeted those silly southern forms with their
ridiculous finger-less wings and upside-down ankles.

Dan