Re: Re-emergence of lost features.

[John Bois <jbois@umd5.umd.edu>]

As an Australian and a placental I have an identity problem.  Sometimes it
makes me say things I later regret.  To my marsupial brethren: I
apologize.

On Sat, 14 Mar 1998, Matthew Troutman wrote:

> Some comparative studies trying to see the intelligence of 
> some marsupials have shown that many are smarter than your common 
> eutherians. 

I would like to read these if you have the refs.  My comments came from my
memory of Lillegraven's "Reproduction in Mesozoic Mammals".  He notes that
due to their mode of reproduction placentals
"thus show greater rates and degrees of cerebralization than
marsupials...".  While marsupials are wonderfully diverse and skillful it
must be admitted that this brain space must count for something.
Lillegraven notes the lack of social groupings, social hierarchies, and (I
think) the lack of play among marsupials.
But then he notes that very little is "known about the relative
intelligence of marsupials and placentals."

> They also have a higher learning capacity. I happen to own a 
> pet marsupial, a sugar glider ( _Petaurus breviceps_) and it is not only 
> smart, it is has very acute sensory abilities ( I've seen it jump and 
> catch things in mid-air in very, very dark areas.) 

I own a male and female Gray Short-tailed opossum.  They are also active
at night.  Their eyes protrude way out of their face.  What sort of
sensory equipment would be the best aid to locating a phorusrhacoid
nest--probably olfactory.  I wonder how marsupials rate with this?

> Marsupials are not inferior in their 
> intelligence, sensory ability...

Then what is the purpose of placentals possessing all those extra neurons?

>...or reproduction ( the marsupial 
> reproduction though it produces far less offspring, is very easy on the 
> mother and produces a more stable species community). 

How? Unless it makes a community which moves at a slower pitch.  It would
be easier for a phorusrhacoid to get along in such a community.