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Re: Theropod "migrations"



At 12:48 PM 4/23/99 -0400, Larry Febo wrote:
>...
>variety were "more alike across continents" .Here Currie explains that
>"Hunters are more mobile than their prey, quicker to exploit new
>areas....and....tolerate a wider range of enviornments..."
>I don`t know if I follow that reasoning. Why wouldn`t the herbivores make
>the journey as well (after all, it`s proposed that they were likely to have
>undergone long distance seasonal migrations).

Migration and *immigration* are two different things.

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.

Indeed herbivore migration is often to *avoid* environmental change.  That
is herbivores tend to migrate in a manner that keeps them in a relatively
narrow range of temperatures.  Certainly few, if any, species of herbivore
has a range anything like that of the lion, and none even come close to
that of the wolf.  (The widest ranging herbivore I can think of at this
moment is the American Elk/Wapiti).

Thus, in living forms, Currie's observation holds true.  Carnivores are
more able to exploit new habitat.

--------------
May the peace of God be with you.         sarima@ix.netcom.com