[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Geeze, yet another stupid question.



At 02:34 AM 11/22/96 -0500, Jeff Poling wrote:

>   Dinosauria without birds is paraphyletic.  But what are birds without
>dinosaurs ... polypheletic?  The definition of polyphyletic, it seems to me,
>wouldn't apply in this case.  So what is the proper term?
>
>[The question is rather ambiguous since you must first precisely
> define what you mean by "bird" and "dinosaur".  The way most of us
> here use the words the question is rather non-sensical (just like
> "what would you call the group that includes seals but not mammals?")
> -- MR ]

   C'mon, Mickey, does anybody *really* wonder what I mean by "dinosaur" and
"bird" in the context of this question?

[Yes, quite frankly I do.  The term "bird" in particular has no
 taxonomic significance. -- MR ]

   And, as I understand cladistics, what I am asking is PRECISELY like
asking for the term to describe the grouping of seals outside of mammals.
You would call the group of "mammals excluding seals" paraphyletic.  If
seals are excluded from mammals, they're not mammals.  What is the term to
describe "seals excluding mammals" (as many try to describe birds as being
something "new" and different from dinosaurs, ie they're not dinosaurs) ....
a term *other than* "non-sensical" as you put it?

   The question can be conceptualized using Linnean terminology.  You have
Class Aves (birds) and Order Dinosauria (not birds), considered to be
completely separate.  Order Dinosauria is paraphyletic because it doesn't
include birds.  What is Class Aves because it doesn't show its descendance
from dinosaurs, it isn't nested within Order Dinosauria and thus is a
grouping of birds without dinosaurs.

[You're missing the whole point of my objection.  Precisely how you
 define "bird" or "dinosaur" determines the answer to your question.
 Said answer could be monophyletic, paraphyletic or polyphyletic.  If
 you want a more complete discussion on "what is a bird?" then I
 recommend (among other sources) the Nature paper describing Mononykus
 (then Mononychus). -- MR ]

** Dinosauria On-Line. Home of THE DINOSTORE ** "Those who trade a        **
** (Dino stuff for sale), Jeff's Journal of  ** little freedom for a      **
** Dinosaur Paleontology, Jeff's Dinosaur    ** little security will soon **
** Picture Gallery, and The DOL Dinosaur     ** find they have none of    **
** Omnipedia. http://www.dinosauria.com      ** either." -- Jeff Poling   **