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From: michaelm@bcsaic.UUCP (michael maxwell)
Newsgroups: net.bio
Subject: Re: Bipedalism
Message-ID: <533@bcsaic.UUCP>
Date: Wed, 30-Apr-86 11:25:45 EDT
Article-I.D.: bcsaic.533
Posted: Wed Apr 30 11:25:45 1986
Date-Received: Sun, 4-May-86 06:32:56 EDT
References: <1058@h-sc1.UUCP> <1180@umcp-cs.UUCP>
Reply-To: michaelm@bcsaic.UUCP (michael maxwell)
Organization: Boeing Computer Services AI Center, Seattle
Lines: 25

In article <1180@umcp-cs.UUCP> mangoe@umcp-cs.UUCP (Charley Wingate) writes:
>Jane Goodall found that one of her chimps, having a weakened arm from polio,
>had adapted by using walking much more than is ordinary for chimps.  This
>suggests the reason for bipedalism; the more hands become useful as hands,
>the poorer they perform as feet.

If I may revert to my original question, I agree that there is a lot of
"reason" for bipedalism.  In addition to the usefulness of hands as hands, I 
had heard it alleged that bipedalism was "useful" to the dinosaurs as a means 
of running faster, i.e. bipeds are (in general?) faster than quadrupeds.  The
question then was, why aren't more mammals (outside of man and kangaroos, and
chimps with polio) bipeds?  Bipedalism arose in two orders of dinosaurs (or at
least so I thought--more on this in the next paragraph), while it is almost 
nonexistent in mammals.  If bipedalism is so useful, why is it so rare today? 

One poster (I've seen a quote of part of his article, but not the original)
said that the dinosaurs arose (no pun) from ancestors which were already
bipedal, whereas the mammals arose (declined?) from quadrupedal ancestors. 
If this is true, then I was incorrect in thinking that bipedalism arose 
(independently) in two orders of dinosaurs, and this is probably all the 
explanation I need.
-- 
Mike Maxwell
Boeing Artificial Intelligence Center
	...uw-beaver!uw-june!bcsaic!michaelm