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Re: _Night Comes to the Cretaceous_ Ad Infintium



Shame we can't inbed tables into our posts.......


Verterbrate extinction magnitudes, freshwater aquatic food chains
TAXON                                      # OF K reps
Extinction(%)
------------------------------------Genera -----Families--------------------
---------Genera----Families----------------------------
Osteichthyans                           13              10
38            10
Amphibia                                   13              10
33            13
Chelonia                                    18                4
11            0
Eosuchia                                    1                   1
0              0
Crocodilia                                   4                1
25            0
Total                                            49            26
26            8

Verterbrate extinction magnitudes, terrestial magnitudes
TAXON                                      # OF K reps
Extinction(%)
------------------------------------Genera -----Families--------------------
---------Genera----Families----------------------------
Eolacertillia                                1                    1
100        100
Lacertillia                                  15                   7
27(?)      0
Serpentes                                    2                  1
0(?)        0(?)
Ornithschia                                14                   8
100        100
Saurischia                                  8                    5
                           100            100
Multituberculta                            11                8
36               25
Marsupials                                   4                   3
75               66
Placentalia                                   9                   4
11                25
Total                                            64                37
55                51

from John....
>From J. David Archibald's: Dinosaur extinction and the end of an era: what
the
fossils say (pub. Columbia univ. press)
% species survival in N.E. Montana
Sharks =0
frogs and salamanders =100%
multituberculates = 50%
PLACENTALS = 100%%%%%%%%
marsupials = < 15%
lizards = < 30%
champsosaurs = 100%
crocs and alligators = > 75%

>So it very much depends on which mammals you are talking about.

Precisely. Given that these data sets are looking at the problem with a
different level of resolution, it might still be fair to say that those that
survived were much more likely to be members of freshwater aquatic
ecosystems. However, I say what needs to be done is to take a list of all
these groups (PS NEED BIRD DATA!!) and we need a very simple database: (1)
take each species known prior to the K/T and fields for  family and genera
as well (relational model, third normal form) and simply associate with a
biome type from a drop-down list and boolean (y/n) if survived.
Unfortunately for me, millions of people depend on me to make sure I can get
them their drugs at the best possible price, so I do not have the time to
collect the data. However, I could constuct a MS ACCESS database with a
simple data-entry form, and then with a little guidance from a Prof, could
program the correct math in. Might be a good thing for my upcoming website
for people to hit and put their data in.  See snip. This would let us see
the pattern as a whole.
>Recapitulating, the real challenge to this idea is to explain why
placentals, birds, frogs, crocs, turtles, and lizards survived an event
that killed _all_ large and small (remembering that there must have been
millions of small juveniles present at the time) non-avian dinosaurs
whether they were in hills, deserts, valleys, river terraces, forests,
plains, at all locations around the globe.

>but the great failing of the bolide-as-sufficient idea is
that it does not do a good job in the particulars.

Bolide impact, I argue, is the ultimate causation. The particulars are
proximate mechanisms. However, in the long-run, it is the proximate measures
that have the more interesting information. And that info is more relevant
today given our collapsing eco-sytems. IMHO, more interesting because we
already have a fair idea what will happen if a comet or asteriod strikes a
planet. We have seen the effects first-hand through telescopes. Sad that it
would be easier to push a bolide off-course than it is to restore an
ecosystem.  The question is are we ready to work with an a priori assumption
( I will admit, I write the word assumption with great trepidation) of the
ultimate causation and then focus on the proximate mechanisms for particular
ecosytems in particular geographic locations. FORENSIC ENVIRONMENTAL
PALEONTOLOGY.

dlessin@accesschicago.net
David.Lessin@Walgreens.Com
David.Lessin@EMC.Walgreens.Com



-----Original Message-----
From: John Bois <jbois@umd5.umd.edu>
To: David Lessin <dlessin@accesschicago.net>
Cc: dinosaur@usc.edu <dinosaur@usc.edu>
Date: Monday, August 10, 1998 1:04 PM
Subject: Re: _Night Comes to the Cretaceous_ Ad Infintium


>
>
>On Sun, 9 Aug 1998, David Lessin wrote:
>
>> The problem here is one of resolution. Catastrpohic extinctions WILL look
>> like a gradual extinction if too "coarse" a scope is taken. In order to
>> regress the dangers of pseudo-extinction from the question at hand,
simply
>> do not look at species level extinctions. Look at the number of familial
and
>> genera represented before and after the extinction event. Individual
species
>> evolve much more quickly than families and genera. It is unlikely that
all
>> members of a family or genus would be caught in the middle of a
speciation
>> event during anytime, never mind a mass extinction event.
>
>And when you do that and other adjustments the kill rate goes down,
>according to Archibald: "In comparison to other intervals in the late
>Cretaceous and early Paleocene, the K/T vertebrate turnover which is only
>10% higher at the generic level."
>( source for this is at
>http://cass.jsc.nasa.gov/meetings/programs/kteventwa.txt)
>
>> Yes it is true that many taxa were in a decline during the late
Cretaceous.
>> This decline, however, was in all likelihood, not significant enough to
wipe
>> out whole families GLOBALLY!
>
>But universality is a problem for all explanations (see below).
>
>>  51% of all families (55% of the genera) in
>> N.A. that have been associated with terrestial food chains were wiped out
at
>> the K-T, whereas only 8% of families (26% of genera)from  freshwater
aquatic
>> foodchains. Bony fishes, lissamphibia, turtles, and crocodylians show far
>> greater survivabilty than lizards, snakes, dinosaurs, and MAMMALS.
>
>>From J. David Archibald's: Dinosaur extinction and the end of an era: what
>the
>fossils say (pub. Columbia univ. press)
>% species survival in N.E. Montana
>Sharks =0
>frogs and salamanders =100%
>multituberculates = 50%
>PLACENTALS = 100%%%%%%%%
>marsupials = < 15%
>lizards = < 30%
>champsosaurs = 100%
>crocs and alligators = > 75%
>
>So it very much depends on which mammals you are talking about.  And I
>really can't think why a bolide winter would favor placentals over
>marsupials.  A more plausible explanation for this differential is
>competition, i.e., placentals were outcompeting multis and marsupials!
>And if this is so you have another major element missing from the
>so called mass extinction.
>
>> In modern
>> ecology, it also well-understood, that freshwater aquatic biomes can
recover
>> much more quickly than other ecosystems.
>
>But there are easier explanations than the bolide.  For example,
>regressing seas create more stream systems.  This was occurring just at
>this time.  (This also explains the disappearance of sharks and rays from
>this particular strata).
>
>> Further....., there is DIRECT evidence of PRIMARY SUCCESSION across much
of
>> this continent (from New Mexico to Saskachewan)- strangely enough, these
>> sediments are deposited directly on top of the layer containing the
iridium
>> spike!
>
>And yet at other locations (Europe, for example) searches for such a spike
>have been unfruitful-even in places with a continuous sequence across the
>K/T.  So universality is an issue here as well.  I know it is difficult
>for any theory, but the great failing of the bolide-as-sufficient idea is
>that it does not do a good job in the particulars.  How long a period of
>photosynthesis reducing conditions is long enough to kill all
>non-dinosaurs but leave all placentals unharmed?  How hot is hot enough to
>kill all non-avians but enable mass survival of avians?  How cold is cold
>enough...  How many firestorms?  How much acid rain is enough to kill all
>non-avian dinosaurs and allow frogs and salamanders to live.  The devil
>really is in the details.
>
>> Given that all animal life is dependent upon plant life, I would pay more
>> attention to the plant fossil record to determine what really happened to
>> different animal groups at the K-T.  If anyone is interested, I have
>> several references on this subject and will be glad to send them
>> off-list.
>
>I am sure there are enough of us interested for you to post these
>publicly.
>
>Recapitulating, the real challenge to this idea is to explain why
>placentals, birds, frogs, crocs, turtles, and lizards survived an event
>that killed _all_ large and small (remembering that there must have been
>millions of small juveniles present at the time) non-avian dinosaurs
>whether they were in hills, deserts, valleys, river terraces, forests,
>plains, at all locations around the globe.
>
>