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Re: Impact QUestion - Re: The birds vs. the pterosaurs

Hi Rich,

At 12:43 PM -0700 2/11/01, Richard W Travsky wrote:
On Mon, 12 Feb 2001, Dann Pigdon wrote:
 Not all the plants would have died. Those living in polar environments
> would have been used to going several months with complete darkness.

Antarctica had a unique environment due to the geographic location of the continent, and the types of currents developing about it.

 > Other species elsewhere could also have become dormant. Insects

Where was the equator at the time of the impact

Sorry to do this but it is a wide open door - In the same place that it is now, at ZERO degrees latitude. ;^)

Now, if you mean where was north America at the end of the late Cretaceous then: go here for a look at the current more or less accepted configuration:

 and where was the impact
located in relation to the equator?

I will conclude, that with your questions that you are looking at a particular single "impact" event - keep in mind that there have been several impacts throughout geological time - just look at the moon; the only difference is that on this planet we have erosion and weathering. Keep in mind also, that Ir is a "heavy mineral" and is prone to concentration, and has other sources. (Devil's Advocate) To answer your question with a visual go to http://www.scotese.com/K/t.htm and check the "Paleomap" pages and you will note that North America was just about almost in the position that it is in today, and where the impact crater that everyone focuses would have been, with respect to your questions.

 If the impact occurred in the summer
of the impact's associated hemisphere, would this not have given an
advantage to the organisms in the hemisphere that was in winter? (Side
question: did summer and winter exist as we know them?)

Paleoclimate is indeed something many of us are interested in. A true Circumpolar Current did not set up in Antarctica simultaneously with the impact. The Deep Freeze took a bit later to occur. It had to wait until the continents drifted a bit farther apart. Note that by the Miocene (http://www.scotese.com/miocene1.htm) Antarctica was "orphaned" by the currents and as such, all was in place for some rather cold weather to become the 24/7 norm. Ocean currents have an intense effect on continental climate.

 I say "advantage"
as these organisms would already have been in a "powered down" mode...

Not necessarily - only, if they did it.

(tell Brent please, if you see him, that I need to talk to him tomorrow wrt my Friday afternoon phone call)

Marilyn W.
                        =00=  =00=  =00=  =00=
                        Marilyn D. Wegweiser, Ph.D.
                Adjunct Curator of Vertebrate Paleontology
                     Cincinnati Natural History Museum

Assistant Professor of Geology
Department of Geology                   mdwegweiser@bsu.edu
Ball State University                   Office: 765-285-8268;765-285-8270
Muncie, Indiana                         FAX:    765-285-8265