Re: Big Bad Bolide vs. Evil Ecological Encrouching (was KT Boundary)

[Mark Hallett <marksabercat@yahoo.com>]

Rob, In your last post just now you mentioned that ALL
seagoing reptiles were wiped out. Is the geological
range of living marine chelonians known? I'm no turtle
expert, but if these were around before or during the
K/T Event, this possible exception to the otherwise
total marine reptile extinction might be a fruitful
subject for comparative research, i.e., why did the
big guys like Archelon go extinct and not the living
taxa, IF the living taxa were around.... Mark Hallett
--- Rob Gay <rob@dinodomain.com> wrote:
> > Bolide hypo accepts no burden.  For example, what
> firepower:angle of
> attack:terrestrial substrate:latitude of impact
> combination would be
> required to remove neornithines as well as
> enantornithines?  What range of
>  megatonnage would leave no dino alive, yet leave
> mammals, birds, crocs to
> carry on?<
> The energy released/angle of attack/etc. doesn't
> matter, as long as it's
> sufficient enough to stop photosynthesis via
> orbiting detritus...that's your
> primary killer right there. Kill off
> photosynthesizing plankton=oceanic
> ecosystems collapse. Kill off photosynthesizing
> terrestrial plants go
> extinct...and honestly, it doesn't matter if
> "darkness at noon" lasted for 3
> weeks or 12 months, or whatever length of time you
> prefer...if it lasts long
> enough to knock out green plants, its long enough (I
> don't know enough about
> plant biology to say anything about the time certain
> groups of plants can go
> without sunlight)...and what you're left with, in
> both cases, is carrion
> feeders and animals with the ability to control
> their metabolic rate.
> In the above quotation, you say that the bolide
> hypothesis says that impact
> speed and angle of attack are primary to the
> extinction, and start throwing
> out somewhat hypothetical questions. Let me throw
> some other questions back:
> What environmental catastrophe/niche
> failure/migration could eliminate ALL
> seagoing reptiles, many clades of fish, all
> ammonites, all non-avian
> dinosaurs, many avian dinosaurs, many types of
> mammals, and leave only
> moderate sized crocs, some mammals, and some birds,
> globally?
> What wave of outside animals decimated dinosaur
> populations in India (which
> didn't hit Asia until the Eocene, right?)...what
> environmental change forced
> all dinosaurs to go extinct on Madagascar...who
> invaded Antarctica, forcing
> the marine reptiles and dinosaurs to die out there?
> While we know that outcompetition does occur, and
> ecosystems collapses do
> occur (especially in this time of man-made dams and
> pesticides, and what
> not), they don't occur on a global scale (man-made
> ones excluded). While
> animal X may force animal Y to extinction in one
> environment, it does not
> stand to reason that Clade X will force Clade Y into
> extinction...we still
> have monotremes around, don't we?!?! Neither
> marsupials nor placentals have
> managed to outcompete them yet...
> The global famine/outcompetition scenario just
> doesn't appear to offer up a
> solution to all the questions posed by the MASS
> extinction...you're wary
> because the impact theory does. It's good to
> question, of course (which is
> why I'm really enjoying this conversation)...but if
> one hypothesis better
> fits the evidence than another, there's probably a
> reason...
> Peace,
> Rob
> 
> Student of Geology
> P.O. Box 20840
> Flagstaff, Az. 86011
> http://dinodomain.com
> http://www.cafepress.com/robsdinos
> AIM: TarryAGoat
> 


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