Re: avian nomenclature

[Tim Williams <tijawi@yahoo.com>]

Saint Abyssal <saint_abyssal@yahoo.com> wrote:


> Why is bird taxonomy so chaotic?


Yep, 'chaotic' sums it up.  The contents and monophyly of many bird orders is 
still in a state of flux.  Also, in many of these classifications oddball or 
hard-to-place taxa are often given their own order (like the hoatzin, or 
cuckoo-roller).  When a molecular phylogenetic analysis finds that a particular 
bird species no longer belongs to a known order, it's assumed to represent its 
own lineage.  But it might just be a 'rogue' taxon, playing havoc with the 
analysis.


The trouble is that (with few exceptions) we lack fossils from at or near the 
critical branching points in neornithean evolution, corresponding to when 
different 'orders' first appeared.  A similar problem occurs with placentals.  
I'm certain we know more about the relationships of non-avian theropod taxa 
than we do about the relationships of modern bird orders (Neornithes).


> Shouldn't genetics be able to resolve disputes quickly? 


Molecular phylogenetic analysis ("genetics") is no silver bullet.  Some people 
treat this method as if it's a panacea to resolving the relationships of extant 
taxa; but unfortunately it's not that easy.  Molecular analyses have just as 
many flaws and quirks as morphological ones - some the same, some different.  


Cheers

Tim