Re: A long post about DUMB METATHERIANS vs EVIL, SMART PLACENTALS

[Ronald Orenstein <ornstn@home.com>]

At 06:48 AM 21/05/01 -0400, John Bois wrote:
> I think this was _my_ point.  Others are arguing that opossum radiation in
> NA shows they are competitive with placentals.  But, if man has disturbed
> the environment so much that competition doesn't occur, this argument is
> nullified. (I reiterate that I would not be surprised if the opossum were
> fully competitive or even superior in specific niches)

Then what is the point?  How many species are competitive in all 
niches?  The fact remains that the opossum has expanded its range and 
numbers considerably in North America at the same time as placental species 
with similar tendencies have also increased in human-disturbed areas (eg 
raccoons, foxes, skunks, even Norway rats).  Didelphis opossums are very 
common in South America, as are many other species despite the presence of 
placentals of many species that could be potential competitors (including 
primates, procyonids and rodents).  There is no evidence AT ALL that these 
species are being "outcompeted" by any placental that I am aware of.

John seems to be reasoning teleologically: he has decided that all 
marsupials are "inferior" to all placentals, therefore opossums must be 
unable to compete with placentals no matter what the facts say.  This is in 
the same category as the Feduccia argument that dino integument can't be 
feathers because there are no feathered dinos, dammit....


--
Ronald I. Orenstein                           Phone: (905) 820-7886
International Wildlife Coalition              Fax/Modem: (905) 569-0116
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