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Joseph:
You said:
Is it possible that the fossil record is over-represented by
sauropods and other very large animals (I mean in relation to other smaller
animals)? The thought came to me that the very large bones might improve
fossilization by taking longer to dispose of and will thus have more of a
chance
to fossilize, at least a piece of them anyway, than smaller animals.
Does this make any sense at all or should I toss it on the huge pile of
interesting but wrong possibilities?
No, quite astute, actually. What you're after is something called
taphonomy, the study of how things in the biosphere make their way into the
lithosphere or, more colorfully, how dead things decay, breakdown, and are
fossilized.
What I'm about to tell you is culled from various sources, but to briefly
answer your question, yes, bigger animals tend to have a preservational bias
up to a point, but really large animals have a lot working against them,
actually, because even though some parts of the body may be preserved, many
parts rot away or get destroyed diagenetically. Cases in point: sauropod
skulls, calcanea, and many times the feet (sorry, had to say it guys).
Birds have a remarkable fossil record considering how poorly they preserve.
Perhaps small dinosaurs, with their fragile, birdy bones, are biased against
preservation and so, as you seem to be suggesting, we're getting a skewed
picture of dinosaur size range and number of big dinos vs. small. Perhaps.
I've been fond of this scenario.
However, many dinosaur sites with the real big dinos also will contain good
skeletons of small reptiles, amphibians, and fish, so the argument about
small dinos being biased against should also apply to these little critters,
too. Perhaps there is not as much a bias against dino size in this case.
I am not near my references now, but I'll post some taphonomic refs later in
the day if you're interested.
Hope this helps,
Matt Bonnan
From: Joseph Daniel <jdaniel@aristotle.net>
Reply-To: jdaniel@aristotle.net
To: dinosaur@usc.edu
Subject: sauropod quantity
Date: Fri, 17 Sep 1999 09:43:57 -0500
Someone made a comment about such a large number of very large animals and
that
got me to thinking. Is it possible that the fossil record is
over-represented by
sauropods and other very large animals (I mean in relation to other smaller
animals)? The thought came to me that the very large bones might improve
fossilization by taking longer to dispose of and will thus have more of a
chance
to fossilize, at least a piece of them anyway, than smaller animals.
Does this make any sense at all or should I toss it on the huge pile of
interesting but wrong possibilities?
Joe Daniel
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