RE: User-friendly classification (was Ankylosauromorpha)

["R. Irmis" <rbi@dana.ucc.nau.edu>]

Ken, I guess you didn't catch the oh so subtle undercurrent in Dr. Holtz's
message.  Oh well.  By the way, you didnt answer Mike's question...what
happens in cladistics?

Regards,
Randall Irmis

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
Ken Kinman
Sent: Thursday, January 31, 2002 9:41 AM
To: mike@tecc.co.uk
Cc: dinosaur@usc.edu
Subject: User-friendly classification (was Ankylosauromorpha)



      This is a wonderful question Mike.  What do we do when we find a new
fossil on "stem 4"?  The answer using the Kinman System is straightforward
and easy to understand (i.e. user-friendly classification).  Before the new
fossil was discovered (call it genus "4-us"), I could have classified them
as follows (Nodosauridae splits off first):

   1  Nodosauridae
   2  Polacanthidae
   3  Ankylosauridae

Now we find this new fossil genus "4-us" on stem 4, and all we have to do is
insert a Plesion as follows:

   1  Nodosauridae
   2  Plesion 4-us
   3  Polacanthidae
   4  Ankylosauridae

Eventually if you find something that is a sister group to 4-us, you could
then erect a formal Family 4-idae for them.  The Kinman System gives you
this flexibility to insert new forms without messing up the established
classification (and without having to constantly create more and more clade
names).  It was a great question!!!
             ------  Cheers,  Ken

******************************************
>From: Mike Taylor <mike@tecc.co.uk>
>Reply-To: mike@tecc.co.uk
>To: dinosaur@usc.edu
>Subject: Re: Ankylosauromorpha page
>Date: Thu, 31 Jan 2002 16:01:07 GMT
>
> > Date: Sat, 19 Jan 2002 19:43:28 -0800
> > From: "Mickey_Mortimer11" <Mickey_Mortimer11@email.msn.com>
> >
> > Isn't the _obvious_ phylogenetic taxonomy for Ankylosauria-
> > Ankylosauria- everything closer to Ankylosaurus than Stegosaurus
> > Nodosauridae- everything closer to Nodosaurus than Ankylosaurus and
> > Polacanthus
> > Polacanthidae- everything closer to Polacanthus than Nodosaurus and
> > Ankylosaurus
> > Ankylosauridae- everything closer to Ankylosaurus than Nodosaurus and
> > Polacanthus
> > What would have been so hard about that?
>
>... feeling suitably chastened by Thomas Holtz's gracious rebuke, I
>venture to dip my poor little toe in the freezing cold waters of
>classification once more ...
>
>I have a question about Mickey's suggestion here.  It's nothing to do
>with ankylosaurs _per se_, but just with how different taxa can be
>related.
>
>I guess we're all familiar(*) with node-stem triplets in which a
>node-based taxon is neatly partitioned into two parts, which are
>stems.  For example, the node {Neornithes + Allosaurus} = Avetheropa
>is partitioned into the stems {Allosaurus <-- Neornithes} =
>Carnosauria and {Neornithes <-- Allosaurus} = Coelurosauria.
>
>(*) If that didn't make any sense to anyone, there's a primer at
>http://www.miketaylor.org.uk/dino/faq/s-class/phyletic/index.html
>
>But what Mickey's talking about here implies a sort of node-stem
>quadruplet:
>
>Nodosauridae = stem {Nodosaurus <-- Ankylosaurus, Polacanthus}
>Polacanthidae = stem {Polacanthus <-- Nodosaurus, Ankylosaurus}
>Ankylosauridae = stem {Ankylosaurus <-- Nodosaurus, Polacanthus}
>       ... and therefore we can't help but think about ...
>SomeNode = node {Nodosaurus + Ankylosaurs + Polacanthus}
>
>(PLEASE, let's not get sidetracked into discussion stuff like whether
>SomeNode is Ankylosauroidea, or equivalent to Ankylosauria, or
>whatever.  And no, I am NOT trying to have people consider the name
>"SomeNode" as published :-)
>
>My question is this: if that kind of three-fold splitting of stems is
>used, don't people feel uncomfortable about the left-over stuff on the
>stem closest to the root?  Suppose it happens that ankylosaurs and
>polacanths are more closely related to each other than to nodosaurs,
>like this:
>
>       Nodo.  Pola.  Anky.
>         \     \    /
>          1     2  3
>           \     \/
>            \    /
>             \  4
>              \/
>               \
>
>Then in this topology, it's clear that everything on the branch I've
>labelled 1 is in Nodosauridae, everything on 2 is in Polacanthidae and
>everything in 3 is in Ankylosauridae.
>
>But what about the poor animals on branch 4 (and on further branches
>that branch off from there, of course)?
>
>* They're certainly not nodosaurids, because they're more closely
>   related to both Polacanthus and Ankylosaurus than to Polacanthus;
>* They're not polacanthids, becuase they're just as closely related to
>   Ankylosaurus as to Polacanthus; and
>   [you can work this out for yourselves, right?]
>* They're not ankylosaurids, becuase they're just as closely related
>   to Ankylosaurus as to Polacanthus.
>
>(But they are, of course SomeNode-ids :-)
>
>In effect, what we have here is an aggravated form of the node-stem
>triplet discontinuity in which the MRCA itself is a member of the
>node, but not of either supposedly-partitioning stem.  We just shrug
>at that problem, because it's only one animal (as in literally on
>specimen, which we'll never find).  But in this case, whole subtrees
>could be affected.
>
>So finally, my actual question is just this: doesn't anyone else but
>me feel uncomfortable about using sets of definitions which leave some
>specimens in this taxonomic no-man's-land?
>
>Thanks for listening.  Hope this wasn't too stupid a question.
>
>  _/|_  _______________________________________________________________
>/o ) \/  Mike Taylor   <mike@miketaylor.org.uk>   www.miketaylor.org.uk
>)_v__/\  "As with most things in life, punctuation doesn't have to
>        be perfect, just good enough to get by" -- Terry Cox
>




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