species ranges (Re: Theropod "migrations")

[Bill Adlam <sagitta_elegans@yahoo.com>]

Stanley Friesen wrote:

> It is an observed fact that *living* carnivores are indeed more
> tolerant of
> variations in environment than herbivores, and have wider
> distributions.
> Wolves (Canis lupus) lived throughout the northern hemisphere north
> of the
> tropics, including forests, prairies, and even into the tundra. 
> Lions
> lived from south-central Africa to central Europe, and well into
> Asia.

I hate to disagree with observed facts, and with everyone else on
this thread, but...

Large carnivorous mammals are observed to have wider distributions
than large herbivores.  But that does not imply that they are more
tolerant of environmental variations.  It could as easily be due to
competitive exclusion.

When competitors (and predators) are removed, domesticated herbivores
can tolerate widely varying conditions.  For example, sheep thrive in
both Middle Eastern semi-deserts and the Falkland Islands (Malvinas
if you prefer).  This is a 'potential habitat' almost as broad as the
wolf's.

Wolves are not a success story.  They have simply failed to speciate,
in contrast to the many ungulate radiations on both sides of the
Bering Straits.

Bill
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