[Taxacom] Poor flying hoatzins dispersed (on flotsam) from Africato S. Am...

Robinwbruce at aol.com Robinwbruce at aol.com
Mon Oct 10 07:16:38 CDT 2011


I am afraid I am with John on this. At the considerable risk of putting my  
head above the parapet and being ignored, vicariance and dispersal are not  
antithetical. The former concerns a spatial and temporal generation of  
taxic difference, i.e. continuity and novel creation within a space/time  
framework; the latter concerns a spatial range extension of the  same taxic 
entity. Why were these two concepts ever linked  thus? Intellectual paralysis? 
Ideological exhaustion?  Or ......what?
 
Robin
 
 
 
 
In a message dated 10/10/2011 5:07:02 A.M. GMT Daylight Time,  
jgrehan at sciencebuff.org writes:

Good  grief. No wonder geologists don't take biogeographers seriously.
According  to the press release the authors say that "We assume that the
bird crossed  the Atlantic upon drifting flotsam.". In other words its
all an assumption,  a fantasy. Creationists are obviously not the only
purveyors of fantasy -  some evolutionists are also deep in the same camp
in this  respect.

John Grehan

-----Original Message-----
From:  taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu]  On Behalf Of Kenneth Kinman
Sent: Sunday, October 09, 2011 10:29 PM
To:  taxacom at mailman.nhm.ku.edu
Subject: [Taxacom] Poor flying hoatzins  dispersed (on flotsam) from
Africato S. America?

Dear All,
A very recently published article provides a probable example of  a
major taxon (Order Opisthocomiformes) establishing itself in  South
America having drifted on flotsam from Africa during the  Cenozoic.
Unlike other such cases, this involves a bird (and a poorly  flying one,
and with a life style which makes it a perfect candidate among  birds to
have made such a trip).    
At  first, I was frankly a bit skeptical, as this dispersal would
have taken  place tens of millions of years ago, and thus not quite the
"slam-dunk"  example of a Nile crocodile making the same dispersal trip
much later in  time.  There is also the problem that the closest
relatives of the  hoatzin are still very uncertain.   
However,  in spite of my initial wariness, I believe it more likely
that the hoatzin  family (presently classified in a monotypic Order) most
likely did (as the  this paper suggested) originate in Africa and
introduce itself into South  America by flotsam dispersal across the
Atlantic Ocean (and then  subsequently went extinct in Namibia, or any
other parts of Africa in which  it may have originally lived).  If there
is another equally likely (or  more likely) explanation for this new
information on hoatzin origins, I  would certainly find it interesting
(given my initial skepticism about such  an unexpected hypothesis).
However, at present I am inclined to see it as  yet another case of
unexpected dispersal (not vicariance).  Anyway,  see one discussion of
this recent paper through the weblink below.   
-----------Ken Kinman     

http://www.sciencedaily.com/releases/2011/10/111004175929.htm   



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