Re: Opisthocoelicaudia (was Re: Titanosaurids)

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

----- Original Message -----
From: <Dinogeorge@aol.com>
Sent: Wednesday, January 23, 2002 10:20 PM


> The big problem with
> cladistics is that there is no way to weight characters, so it becomes a
> phony one-character-one-vote situation.

Only morphological cladistics has this problem. In the molecular world it is
apparently often possible to state in % how much more or less possible it is
that, say, an A in the 2nd position of a particular codon will change into a
G rather than a T.

> You can't equate a character that
> appears everywhere along the spine with a character that is a single small
> lump on a long bone.

Depends on development. Bifid neural spines are definitely one character
(failure of the embryonic left and right neural arches to fuse early
enough), even if -- possibly -- one with much weight. (But wait*, where does
that occur... independently in euhelopodids, diplodocoids, camarasaurids...
that's 3 times. If it can evolve 3 times it can easily evolve 4 times IMHO.)

* Choose yourselves whether a pun is intended :-)