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Re: predators for large animals?



Derek Tearne <derek@fujitsu.co.nz> wrote:
> 
> Future palaeontologists will have a devil of a job sorting out what
> happened here, especially as, overnight, examples of select groups of 
> mammals (us, our domestic animals and retinue of rodent pests) suddenly 
> appear on every continent (imagine the hypothetical land bridges they 
> will construct!).  
> 
> Those future scientists will probably largely discount the role of this 
> medium sized omnivore with soft flattened teeth called Homo.  They 
> certainly won't pick us as being the primary predator of our times.
> 
> I do not envy those future scientists one little bit.

Maybe it will go like this:

The T/Z mass extinction event was accompanied by a sudden increase
in atmospheric CO2 content.  A layer rich in organic, metallic and
short-half-life radioactive residues is associated with a dramatic
decrease in species diversity in terrestrial, fresh water and marine
environments.   Pollen studies show a characteristic `disaster flora'
of single-species cereal grasses displacing established ecological
communities, exactly coinciding with the extinction.
 
The leading theory posits the impact of a swarm of microplanetoids
ejected from the nearby collision of two stars, including both
chondritic accretions (the source of the complex hydrocarbons),
stony/metallic fragments that may represent fragments of a planetary
core, and chunks of material that must have come directly from a
small-scale but very intense nucleosynthetic reaction during the
collision!  A supernova is ruled out because of the peculiar
elemental profile of the boundary deposits, and the fact that the
hydrocarbon tar was not vaporized and dissociated.

Perhaps radioactive and organic mutagens provoked the appearance of
poisonous or inedible grasses, which, with no herbivores able to
control them, displaced ordinary grasses and wiped out first the
large ungulates, their direct predators and in an ecological domino
effect, the fluvial and marine communities which had been stable
for many thousands of years!  Scientists are still puzzled by the
presence of curiously-shaped artifacts of metal and polymerized
hydrocarbon in the boundary layer, which indicate that some
quasi-intelligent species had been learning to use the asteroidal
residues as raw materials for tools and/or display objects, when,
tragically, they too succumbed to the worldwide mass extinction!

[misinterpetation of causes and effects could very well occur]  :-)

Mike Bonham        bonham@jade.ab.ca