[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: "Cope's Rule" Put to the Test

At 09:41 PM 1/21/97 -0500, DinoGeorge wrote:
>I use a rather different form of Cope's rule: Large organisms tend to evolve
>from smaller organisms rather than vice versa. The version of Cope's rule in
>parentheses above is obviously false and never needed any kind of 10-year
>study for disproof.

Even this formulation is not entirely true, as the fossil pygmy elephants
from the California Channel and Mediterranean islands show (and also,
probably, the Inaccessible Island Rail, just to give a maniraptorian example).

What might be better to say is that as the vast majority of living animals
are small, and as we all evolved from tiny critters somewhere down the line
(Pikaia?), any animal above a certain size must,somewhere in its lineage,
have evolved from smaller ancestors, and the ancestry of any really huge
animal must include a number of creatures of gradually increasing size that
could be placed in a temporal sequence (though there might have been some
reversals along the way - at least some of the modern mammalian megafauna
may (I think?) have recent ancestors that were larger than their modern
descendants).  This situation might give the APPEARANCE of a general trend
such as that stated in Cope's "rule", when it is really only an observation
that really big animals must at some level have evolved gradually from
smaller ones.
Ronald I. Orenstein                           Phone: (905) 820-7886
International Wildlife Coalition              Fax/Modem: (905) 569-0116
1825 Shady Creek Court                 
Mississauga, Ontario, Canada L5L 3W2          Internet: ornstn@inforamp.net