Re: body size and the species/genus ratio

["Tony Canning" <tonyc@foe.co.uk>]

On Apr 28, 10:34am, Colette H. Adams wrote:
> Subject: body size and the species/genus ratio
> What I wish to achieve is an understanding of why, for example, mammals
> stayed so small during most of the Mesozoic, while no dinosaur that we know
> of was smaller than a ferret.
>

The fact that several mammalian lineages increased in size after K/T
does suggest that competitive exclusion was operating - perhaps by
small, probably feathered active dinosaurs of the bird-like clade
(I mean the things that are often referred to as primitive birds which
were not actual bird ancestors, eg Cretaceous forms).  However, we
shouldn't neglect abiotic factors (climate etc) as possible factors.

  It is true that in
> many cases the groupings do not reflect this.  For example, turtles and
> crocodilians are lumped together in the class Reptilia.  But few doubt that
> crocodilians are much more closely related to birds than to turtles.  I
> would prefer to see the four main lineages that arose from stem reptiles be
> the basis for classifying reptiles and their descendants.  But this does
> not change the fact that higher-level classification does to one degree or
> another reflect phylogeny.
>

I don't see the problem here - there are many, many monophyletic groups
within the monophyletic Reptilia (which includes dinosaurs & birds,
obviously).


> There are lots of good reasons to have a standardized nomenclature, and
> that is what the ICZN is for.  None of them, however, have much to do with
> science.  If this were the case, every scientific field would have a list
> of "standardized" working hypotheses.

The utility of unique names is obvious, as you say, and it is useful to
name other clades - I don't think the ICZN is interested in the CONTENTS
of a clade which is the hypothesis open to testing and refutation.
There are many of us who would like to see Classes, Families etc consigned
to history's dustbin, but there is no reason why the names should not
be retained, if they are useful for communication.


> The way that credentials came into this discussion is that it was suggested
> that Greg Paul did not have any "scientific" credentials.  Presumably this
> is supposed to justify giving his ideas less credence.

If Greg Paul uses scientific method, which he does, he is a practicing
scientist and deserves to be respected as such.  It doesn't matter what
degrees one does or doesn't have, nor what one does for a living - the
knowledge and understanding are what matters.  A degree or three is the
USUAL route for getting started down the road of scientific knowledge
but is not the only valid route.   In fact, the degree route is the EASY
way...

Best of luck with the mammal problem..

Tony