DUMB METATHERIANS vs EVIL, SMART PLACENTALS

[<darren.naish@port.ac.uk>]

On metatherians vs placentals and so on....

I haven't been following this thread, so apologies if I'm adding 
comments that don't add up to much BUT - - the concept that 
metatherians are somehow intellectually (??) or 'adaptively' (??) 
inferior to placentals is surely very very flawed. I don't know if John 
Bois is actually stating this in his communications but the inference is 
certainly there.

Marsupials successfully invaded Europe, eastern Asia and northern 
Africa during the Palaeocene-Eocene and stuck it out in Europe until 
the Miocene. In historical times,  _Didelphis_ has moved north 
through N. America and now occurs as far north as Canada. This all in 
the proverbial face of established placental competition. Also worth 
noting is that Australasia is far from a 'marsupial haven': murids have 
(probably) been in Australia since the Eocene yet there has never been a 
mass die-off of small Aussie marsupials at the hands of ruthless clever-
witted rats and mice. 

John wrote...
 
> Then how exactly did marsupials get snuffed when placentals
> didn't?  Marsupial bolide homing device? 

The [Cretaceous] animals being discussed are not marsupials: they are 
metatherians. John's theories seem to rely on simple notions of 
competitive replacement, an idea that is too simple when we're talking 
about ecologically diverse groups consisting of hundreds of species. 
Other researchers recognised this several decades ago.

DARREN NAISH 
PALAEOBIOLOGY RESEARCH GROUP
School of Earth & Environmental Sciences
UNIVERSITY OF PORTSMOUTH
Burnaby Building
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