Re: Opisthocoelicaudia (was Re: Titanosaurids)

["David Marjanovic" <david.marjanovic@gmx.at>]

----- Original Message -----
From: <Dinogeorge@aol.com>
Sent: Wednesday, January 23, 2002 8:20 PM

> And
> if we're going to invoke homeobox genes in the formation of the tail, why
not
> invoke them to explain all kinds of other character anomalies in
cladograms
> as well?

Because developmental geneticists already have an idea about what hox genes
can and can't do (they are e. g. involved in segmentation issues). There is
science in this. You know about the most extreme case, *Sellosaurus*, which
exhibits ?sexual dimorphism in its sacra -- one morph has a dorsosacral and
2 true sacrals, the other has 2 true sacrals and a caudosacral? And about
giraffes, which have transformed the last cervical into a dorsal and have
duplicated another cervical to arrive at 7 cervicals again?

> This would make morphological cladistic analysis pretty much
> worthless.

At the contrary, it can tell us when hox mutations can have occurred.