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dinosaurs as failures?
Of course, failure is a rather subjective term, but there are some
groups that could be viewed as failures, at least in terms of being very
diverse and abundant for a long period of time, and then not being able to
compete under adverse conditions.
One of the prime examples in my view are the trilobites, which did
extremely well in the early Paleozoic, but suffered a slow decline until the
end-Permian extinction finally did them in. Ultimately however, they may
have just been too vulnerable during the moulting stage to increasingly
advanced predators. But this is just one theory. In any case, I would
think of them as a better example of failure than non-avian dinosaurs. And
even their horseshoe crab cousins are pretty unsuccessful compared to their
terrestrial cousins (scorpions and arachnids). Hyoliths are perhaps the
mollusc equivalent of the trilobites, although their decline wasn't quite as
bad, and they might have survived if the Permian extinction hadn't been so
massive.
At least it took quite a massive worldwide catastrophe to do in the
non-avian dinosaurs. They were just too specialized in their requirements
for a relatively continuous supply of food which is not a good thing when
times get bad. The meek little generalist mammals on the other hand
inherited the earth through a combination of luck, generalized feeding
strategies, underground living, torpor, and other advantages that the
non-avian dinosaurs just didn't need while times were good. They did great
while the party lasted, but kicked the bucket when times got really rough.
Even the avians probably just made it through by the skin of their teeth or
beaks. Ammonites are the other major victim of the KT, which we often
regard as failures since they left no descendants. Just too dependent on
plankton in their larval stage.
But you could call non-mammalian synapsids (which eclecticists call
Synapsida) a failure. Devastated by the Permian and almost wiped out by the
Jurassic-Cretaceous extinction. But their mammal descendants are the
ultimate Cenozoic success story, while the dinosaur descendants (birds)
haven't done too badly. That is why we give the successful mammals and
successful birds separate Class status in eclectic classification, and
regard non-avian dinosaurs and non-mammalian synapsids as failures. It's a
matter of perspective (and in my mind neither cladistic nor eclectic
perspectives are superior to one another).
Perhaps these vertebrate examples are not near the failures the
trilobites and ammonites were, which left no living descendants at all, but
failures nevertheless. Class Sarcopterygea is another failure in relative
terms. Did quite well from the Devonian to Carboniferous, but outdone by
both their sister group (Class Actinopterygea) and also their tetrapod
descendants. Some coelacanths and lungfish still around, but hardly a
success story. And monoplacophoran molluscs are hardly a modern success
story either, with less than a dozen living species.
But when it comes to long term survival, no eukaryote can hold a
candle to the prokaryotes. The great extinctions at the end of the Permian
and Cretaceous were a cake-walk for the bacteria. Even insects can't begin
to compete with them.
--------Ken
*******************************************************
From: Dinosaur Interplanetary Gazette <dinosaur@dinosaur.org>
Reply-To: dinosaur@dinosaur.org
To: ssampson@umnh.utah.edu, dinosaur@usc.edu
Subject: Re: dinosaurs as failures
Date: Wed, 11 Jul 2001 16:49:23 -0400
The best source on this is "The Last Dinosaur Book" by J.T. Mitchell. I
believe it's still in print.
It was discussed at great length on the list about two years ago, so you
might
search the archives for the relevant posts.
E.S.
Scott Sampson wrote:
> Folks,
>
> As we all know, dinosaurs are often put forth as the ultimate example of
> failure, simply because they are no longer with us (birds excluded). I
am
> collecting examples of magazine and television advertising that have
> made use of this inappropriate analogy. Thus, if any one out there
knows
> of any good examples of this (and can provide the reference or source),
I
> would greatly appreciate the input. Please respond offline. Thanks
very
> much.
>
> Scott Sampson
>
> __________________________________
>
> Scott D. Sampson, PhD
> Curator of Vertebrate Paleontology
> Assistant Professor of Geology and Geophysics
> Utah Museum of Natural History
> University of Utah
> 1390 East Presidents Circle
> Salt Lake City, UT 84112-0050
>
> Phone: (801) 585-0561
> Fax: (801) 585-3684
> Email: ssampson@umnh.utah.edu
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