Re: The Papers That Ate Cincinnati

["T. Michael Keesey" <keesey@gmail.com>]

On 5/6/07, Nick Pharris <npharris@umich.edu> wrote:
> The problem for etymologizers like myself is that we experience
> cognitive dissonance when the coverage of an apomorphy-based name like
> Mammalia doesn't match up with the distribution of the apomorphy in
> question (assuming, of course, that the apomorphy arose only once).

For this reason, the latest draft of the PhyloCode includes a
hyphenated prefix, "Apo-", which can be used with a crown clade name
to denote an etymological apomorphy-based named. To take your example,
if _Mammalia_ is defined as a crown group (e.g., the final common
ancestor of _Ornithorhynchus anatinus_ and _Homo sapiens_, and all
descendants thereof), then "Apo-Mammalia" may be defined as, e.g.,
"the initial ancestor of _Mammalia_ to possess mammary glands
homologously with those in _Mammalia_, and all descendants thereof".
(Note that this would self-destruct in the unlikely event of lactation
turning out to have arisen separately in monotremes and therians.)

> Maybe we could
> restrict the use of apomorphy-based names to apomorphy-based clades,
> and use all eponymous names for node-and stem-based clades?

I think that's a bit of a tall order, although it might work well in
some instances. Depends on the apomorphy/ies and how the name is
commonly used.
--
Mike Keesey