Re: DINOSAUR digest 3384

[Jorge Dichenberg <jorgedich@yahoo.com>]

--- dinosaur@usc.edu wrote:

> > Date: Thu, 10 Nov 2005 21:34:48 +0100
> From: David Marjanovic <david.marjanovic@gmx.at>
> Subject: Re: K/T revisited, was: Re: DINOSAUR digest
> 3382
> To: DML <dinosaur@usc.edu>
> 
> > Everything which eats dead plants
> > (detritus) survived.
> 
> Well... a little bit of those survived.
> 
> > Everything else died out.
> 
> Yes.
> 
> > Survived freshwater fish,
> > turtles and crocs which eat freshwater
> invertebrates.
> 
> *Brachychampsa*, an alligator...oid apparently
> specialized for cracking 
> turtles, did die out. Looks like not enough turtles
> survived to support a 
> layer of carnivores above them.
> 
> > One thing which strikes me is how many different
> > amphibians, small mammals and birds survived.
> > According to genetic analysis, at least 20 clades
> of
> > birds and many mammals, including two already
> separate
> > Solenodons from Cuba and Haiti, which were already
> > separate in Mesosoic and never moved away from
> their
> > islands since!
> 
> Most, or all, of those analyses are miscalibrated.
> 
> And so far none takes the effects of metabolism and
> body size on the rate of 
> molecular evolution into account (published in
> January 2005).

Worth knowing. At least Solenodon phylogeny made it to
"Nature" so is quite reliable. 
 
> > Scenarios like wildfires, acid rain or global
> change
> > of climate are against the facts - big animals are
> > more resistant to that than frogs or small birds.
> 
> Do you think so? Small birds can for example just
> fly away whatever happens, 
> frogs can survive wildfires very easily when they
> are in the water, and so 
> on... 

Yes, I think so. Large forest fires are unlikely to
cause extinction of dinosaurs. 

Modern large mammals escape wildfire at least as well
as small animals by running to water or patches missed
by fire. 

Second, in the scale of Earth, there had to be swamps,
seasonally unvegetated  patches, areas of heavy
rainstorm and similar where forest fires couldnt
spread. Burning of 99% of Earth surface leaves as much
land unburned as all national parks combined. 

Finally - one day after fire, plants begin to regrow
providing food. I assume dinosaurs could survive some
weeks without food (and eggs might much longer).

Of alternative theories: amphibians and freshwater
fish are very suspectible to acid rain. Small birds
are very suspectible to smoke (use of canaries in coal
mines). In modern forest fires, birds drop dead from
smoke. 

I agree there were large scale fires in K/T, but they
cannot explain extinction-survival pattern.

> > Date: Thu, 10 Nov 2005 21:06:58 -0200
> From: Roberto Takata <rmtakata@gmail.com>
> Subject: Re: K/T revisited, was: Re: DINOSAUR digest
> 3382
> To: jorgedich@yahoo.com
> CC: dinosaur@usc.edu

> What about that survive/extinction pattern if we
> look at the marine
> biota? Sharks survived, marine reptiles don't.
> Ammonites go extinct,
> squids don't.

Marine reptiles might qualify as top predators. But I
don't know biology of marine invertebrates well
enough.  
Maybe someone else knows, but they might have larvae
which don't fossilise etc.

Jerzy Dyczkowski  



        
                
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