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

Re: Bradytely, etc.




Hi All,
I wrote a long e-mail responding to David's questions, but decided I should send it privately since most of it is not dinosaur related. I will e-mail the long response to anyone who requests it from me (offlist please).
Bradytely is an unusually slow rate of evolutionary change, and since Tinamiformes (tinamous) seem to be the most bradytelic of living birds, I believe they are genetically the living birds most closely related to dromaeosaurs. And I completely agree with David that another name should have been coined for a "holophyletic Dinosauria" (but as he noted, it's too late now).
Since it is offtopic, if you want to know why I proposed the name Martiobiota (a few years after proposing Geobiota), you can visit my homepage and do a "find word" search for Martiobiota. Nothing fancy, but does contain the text of some of my published papers. The URL of my homepage is:
http://www.geocities.com/CapeCanaveral/5074
------Have a good weekend,
Ken
*********************************************************
From: "David Marjanovic" <David.Marjanovic@gmx.at>
Reply-To: David.Marjanovic@gmx.at
To: "The Dinosaur Mailing List" <dinosaur@usc.edu>
Subject: Re: Bradytely (thanks Jaime) + Trees of Life
Date: Fri, 12 Jan 2001 21:00:02 +0100

> And I also complete agree with you that dromaeosaurs were not
> bradytelic at all, and in my Interstate example, I said that evolutionary
> rates or speeds on the dromaeosaur "offramp" probably did not slow down.
If
> the K-T extinction had killed off all of the birds (Aves) and some
> dromaeosaurs had survived and diversified instead during the Cenozoic, I'd
> be classifying birds as an extinct family (maybe two),


That's why I don't like ranks -- they are closer to the way human brains
work, but what actual information to they carry?

Question -- what is bradytely? A "broad range of goals"?

> and probably be
> defending a Class Dromaeosaurea (and trying to decide whether it is less
> arbitrary to put the bird family in Reptilea or Dromaeosaurea).

That's why I don't like paraphyletic taxa (above the species level, of
course). These examples are all sauropsids, ..., diapsids, ..., dinosaurs,
..., theropods...
        (Nitpicking: I would have liked it if a term had been coined for
holophyletic Dinosauria and if Dinosauria were discarded instead. Dinosaurs
aren't lizards, and "fearfully great" is a generalization. But such a term
isn't there, and even if someone had a good idea for such a name, it's too
late. But Sauropsida, which was coined as holophyletic by Seeley, is there
and can and IMHO should be used instead of paraphyletic Reptilia.)

>      The common ancestor of life on Earth (I use the term "Geobiota",
rather
> than "Biota")

Hm. Good idea at first glance, but if there is or was life on Mars, it is
very likely to have a common origin with that on Earth, because prokaryotes
can very probably travel between planets in rocks blown off of a planet by
an impact, and life may even have originated on Mars and later traveled to
Earth. "Geobiota" could be a misnomer.

How official is "Biota", anyway? I have never seen it in print...

> The only thing I would disagree with (below) is that I believe that
is
> not nearly as difficult as you might think to determine what is
> plesiomorphic for "Archaea". Unlike Woese, I believe that they are a
> comparatively derived and later-evolving branch of thermophilic bacteria
> (and should be called Metabacteria, as Osawa and Hori named them way back
in
> 1979, rather than the totally inappropriate name "Archaea" proposed in
> 1990).


Interesting, why do you think so? (And where would you look for the origin
of Eucarya, which is commonly viewed as the sister group of Archaea?)

> Since 1995, I have been warning that Woesian "Trees of Life" are
> almost certainly totally misrooted and badly skewed as a result. When
such
> trees (actually just "Tree of Ribosomes") are finally discarded and real
> "Trees of Life" replace them, this will be a terrible black eye for
> cladistics, and for a while I suspect it will overshadow and throw a pall
> over the relative successes of cladistics in the study of dinosaurs.


Pardon me :-], I am sure you won't think it's appropriate if I compare this
to Feduccia's statement "The theropod origin of birds, in my opinion, will
be the greatest embarrassment of paleontology of the 20th century", but what
are your arguments? :-]


> *********************************************************
> >From: "Jaime A. Headden" <qilongia@yahoo.com>
> >Reply-To: qilongia@yahoo.com
> >To: dinosaur@usc.edu
> >Subject: Bradytely and Evolutionary Distance: Plesiomorphy
> >Date: Thu, 11 Jan 2001 00:02:26 -0800 (PST)
> >
> > distance logarhythms,

related to arithmetics, not rhythm... :-)

> >   A last example, close to home: Ceratopsidae have numerous
> >autapomorphies that perhaps rival any other dinosaur group. So
> >do Ankylosauria. Slowly, we find basal forms along these
> >highways that reduce the distance each organism differs from a
> >set group as one takes into account the truly gradistic
> >relationship of _all_ taxa.

=8-) That's why I don't like "evolutionary distance" to be used in
classifications. A few new fossils, and taxonomy goes the way of the
pterosaur. :-( .

_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com