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Re: Hell Creek (long)
On Wed, 29 May 2002 15:21:39
> The article in June 2002's
>"Discover Magazine" only puts the icing on the cake for me....
Really? I didn't see much new data at all in this article; really, just a
bunch of rehash.
>animals that by all accounts should have died out because of the massive
>climatic effects that should have taken place via the poisoning of the air
>and water (just like they die out today via industrial pollution).... didn't
>die out like they should have. The ones that did go bye byes were the ones
>that should have survived such an environmental holocaust.
Why? Were dinosaurs really "better" suited to survive an impact? I know this
is often stated as a priori fact, but is there any true evidence of this? If
anything, some larger dinosaurs may be vulnerable. Just a thought.
>Too bad for the impactor lovers..... The blast wave apparently didn't make it
That's a tough statement to make. I think some more study is needed.
>Since I know that the majority have Paul's DA,
Yep, just started reading it!
>I will go so far as to say that with this new study out in Science entitled
>"Ascent of Dinosaurs Linked to an iridium anomaly at the Triassic-Jurassic
>boundary" that deals with finally finding an iridium anomaly (all be it a
>tiny one) at the Triassic/Jurassic boundary, and the apparent take-over by
>the dinosaurs after it, there might indeed be a connection with massive
>impacts and SOME recorded extinction events.....
While I wouldn't go as far as to parrot the entire Raup-Sepkoski hypothesis, I
do think that many studies have shown that most of the major extinction events
are tied to extraterrestrial causes. Whether or not these extraterrestrial
causes were the main causes of some of these extinctions is open to debate,
>To me, this equals malicious environmental effects caused by a volcanic
>onslaught stressing life before the impact(s) did its dirty work.
How exactly would the volcanic eruptions stress life? Was only dinosaur life
stressed? Why wouldn't the volcanoes stress, say, birds, mammals, amphibians,
etc.? Or, did it? Are there any studies?
> and you get a canvas who's paints paint a picture that doesn't
>say impacts are the most important villains when it comes to mass
>extinctions. They are only one in a multitude of players that can conspire
>together in the wrong place at the wrong time to wipe out entire ecosystems
>and their associated dominant fauna and flora. For the KT situation, the
>impact(s) might just have been the last straw that broke the tyrannosaur's
Perhaps...however, there is a general pattern that shows that impacts may be
THE major cause of mass extinctions. Many would disagree, saying the pattern
is basically a function of damn statistics. But, iridium anomalies are known
for a few of the major extinctions.
>The KT was a completely different story, as is being told by Horner's study.
>The dinosaur populations (at least in Montana) were having to deal with the
>environmental shockwaves being left behind and in front of the inland sea as
>it transgressed and regressed across the North American continent. Was this
>same type of scenario being played out on other dinosaur populations on other
>parts of the globe? I have no idea.... though it's highly plausible.
This is what really makes me skeptical. Here in the Late Pennsylvanian of
Illinois we have a continental sea that was constantly transgressing and
regressing (which, of course, leads to the classic cyclothem pattern that is so
prevalent). My preliminary studies have shown that different brachiopod
populations were under stress at certain times, possibly resulting in intense
progenesis that led to early maturity as a vehicle by which to survive and
reproduce. But, this is a very local thing. Certainly it wasn't happening
across the globe, as other brachiopod populations appear stable during this
time. Heck, although they are really reduced in numbers, brachiopods continue
to hold on today.
Horner's study is akin to me saying that brachiopods were gradually dying off
worldwide because they appeared stressed in one part of the Illinois basin.
Even if his data is right, and if I am correct, this only means that
populations and faunas were undergoing change due to stress in one part of the
globe. It is foolish and unscientific to extrapolate to include not only the
entire globe, but the entire lineage of a type of organism. If I claimed that
brachiopods were gradually going extinct based solely on my studies in Illinois
I would be shot down, and certainly any paper I wrote would be sunk in peer
review. Why Horner's study in Hell Creek keeps generating sensational press is
beyond me. It is a good study...a very good study, and it is telling us much
about the environment of Hell Creek during the close of the Cretaceous. But,
extending that to include the entire world is going too far.
I think the evidence points to an impact finishing off the dinosaurs. Was the
population stressed? Possibly. But, this stress, if indeed it was real, was
likely just another episode in the 160 million year history of the dinosaur
lineage, much like similar stresses that occurred in the Triassic and Jurassic.
It may have just so happened that a friggin' huge rock crashed down in the
middle of this stress, and, unlike during earlier episodes, the dinosaurs
weren't able to recover.
These are my thoughts, anyway. More data is needed, though!
Steve Brusatte-DINO LAND PALEONTOLOGY
ONLINE CLUB: http://clubs.yahoo.com/clubs/thedinolanddinosaurdigsite
INTERNATIONAL LANGUAGE SITE: http://www.geocities.com/stegob/international.html
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