K/T revisited, was: Re: DINOSAUR digest 3382

[Jorge Dichenberg <jorgedich@yahoo.com>]

> > Date: Wed, 09 Nov 2005 04:43:15 -0200

> But, yes, we have to answer: why dinos died, and
> frog and crocs
> survived? Maybe they are not so sensitive to
> climatic change in a
> medium term. Some frogs species manage to resist
> freezing.

> > Moving to the other side. I admit that frogs are
> very
> > sensitive animals. So if the Permian-Triassic
> > extinction was caused by a massive drought and
> > increasing temperature and the K-T extinction by a
> > comet impact how did the amphibians survive? In
> WWM
> > the labyrinthodont "cocooned" itself (in what
> > exactly?) in an attempt to wait out the drought.
> Do
> > amphibians do this?

Isn't KT extinction easy? Perfectly selective for
feeding preferences. Everything which eats dead plants
(detritus) survived. Everything else died out.  

Survived insects and fungi eating detritus on land.
And freshwater invertebrates feeding on detritus
carried to rivers and lakes.

Survived insectivores - frogs, small mammals, lizards,
birds - which fed on these insects. Survived
tortoises, which eat fungi. Survived freshwater fish,
turtles and crocs which eat freshwater invertebrates.

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!
 
Shortly, extinction scenario is consistent with
blocking any plant growth for one or several years.
Only food chains were based on decaying organic
matter. 

Also consistent might be my idea of "Edens" in which
very small pockets of land (size of meters or
kilometers) survived almost unscratched due to freak
combination of topography, soil, drainage etc. They
might support sensitive species, but only the smallest
ones.

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.

Jerzy Dyczkowski



        
                
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