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Re: mammal mystery



In a message dated 97-02-16 21:14:04 EST, dunn1@idt.net (Larry) writes:

<< Thriving is precisely what increasing size means.  Animals living in an 
 environment that can support greater size get bigger.  It's been a simple 
 fact since the Paleozoic...>>

This sounds remarkably like a statement of a certain Cope's Rule that has
been bandied about on this list...

<< Can you be serious?  A "group of species" is referred to as a "genus." Do 
 you mean that elephants are doomed because there are no mouse-sized 
 elephants?  Are we doomed because there are no mouse-sized hominids? >>

Elephants and hominids are biding their time, so to speak, until the
inevitable: Just wait until the next large asteroid impact. Extinction has
been the historical fate of all but two genera of elephants and all but one
genus of hominid. But elephants and hominids aren't doomed >because< there
are no mouse-size elephants or hominids. They're doomed because, unlike
small, fecund animals, elephants and hominids are unlikely to give rise to
new species quickly enough in response to a relatively rapid unfavorable
environmental change. Even if there >were< mouse-size elephants and hominids,
the larger members of those families would still be doomed when such an
environmental change occurred. They would, however, likely be replaced by the
larger descendants of their smaller relatives once the environment
restabilized.