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From: friesen@psivax.UUCP (Stanley Friesen)
Newsgroups: net.bio
Subject: Re: why are sauropods as big as they are?
Message-ID: <736@psivax.UUCP>
Date: Tue, 17-Sep-85 11:29:46 EDT
Article-I.D.: psivax.736
Posted: Tue Sep 17 11:29:46 1985
Date-Received: Mon, 23-Sep-85 00:23:32 EDT
References: <188@rtp47.UUCP>
Reply-To: friesen@psivax.UUCP (Stanley Friesen)
Organization: Pacesetter Systems Inc., Sylmar, CA
Lines: 43
Summary: 

In article <188@rtp47.UUCP> throopw@rtp47.UUCP (Wayne Throop) writes:
>
>While thinking about why sauropods are as large as they are, and why
>evolution would have favored such outrageous size, I had a (perhaps
>original) thought.  I seem to recall that many of the "lower" creatures,
>(especially sea-borne ones, but some land-borne also) grow "without
>limit" as long as they live.  That is, they grow until the square-cube
>limitations of their design kills them off, or they die for other
>reasons.  They have no particular point where they stop growing in a
>completed, "adult" size.
>
	This is actually not how indeterminate growth works. Such a
growth pattern does *not* mean that there is no standard "adult" size
(or size range). The growth pattern called indeterminate or
"unlimited" is not linear, it is perpetually slowing. That is size is
not linearly proportional to age, it is proportional to some function
of age like the square root or the logarithm (probably the latter).
This means that after these animals reach a certain size (which may be
called the adult size) they grow *very* slowly, but while they are
young they grow quite fast. The limiting factor is thus not the
square-cube stuff, but the genetcally determined reduction of the rate
of growth with age. Sauropod fossils show quite clearly, based on size
distributions, that the known sizes represent normal adult sizes, not
overmature adult sizes. Actually we have found one Allosaurus(not a
Sauropod) which may well have been extremely old at time of death, it
was almost as large as a Tyrannosaurus.

>I guess I am proposing that size is to sauropods what age is to humans.
>After all, if you look at an average 80-year old man, you'd say he
>simply couldn't compete (physically) in earth-like conditions.  Perhaps
>the larger sauropod finds are a similar phenomenon.
>
	The problem with this is that the only reason Humans live to
such an age is that we protect one another. In solitary species such
extreme old age as we find among humans is almost unheard-of. Even
among other social species where old age does exist, it rarely exists
in such an extreme form as it does in modern society.
-- 

				Sarima (Stanley Friesen)

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