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

Re: *Mauisaurus* vs large pterosaurs




--- On Wed, 10/7/09, Augusto Haro <augustoharo@gmail.com> wrote:


> Whatever the reason for Cope's Rule (and if it generally
> holds true),
> may it not be that the latest members of both lineages,
> that
> extinguished at the same time, where the largest because of
> Cope's
> Rule and not because of some coevolutionary linkage? 

Definitely possible, in my view. However, I do not consider a reflexive 'Cope's 
Rule' to be 'best-fit' any case, in the absence of specific size-drivers such 
as temperature or prey-predator interaction.

1) "If size is an advantage, then size will increase until further size 
increase ceases to be advantageous." 
2) "Things just get bigger."

I consider statement #1 to be useful and valid, but not #2. For many years, I 
thought statement #1 _was_ Cope's Rule, and couldn't understand the 
controversy. Then I found that #2 is a paraphrase of Cope's notorious 
rule-of-thumb.

> After
> all, in the
> latest Cretaceous you also have the largest of other
> clades, such as
> tyrannosaurids and ceratopsians (whose evolution may in
> principle seem
> as possibly also coevolutionarily correlated).

If theropods drove size in pterosaurs, then the speculation that pterosaurs 
drove size in elasmosaurs links them all. Speculatively, of course. Complete w/ 
hand motions...