Message 2003-02-0010: Re: New Dinosauricon Taxon Pages: _Therizinosauria_

Sun, 02 Feb 2003 16:06:55 -0800 (PST)

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Date: Sun, 02 Feb 2003 16:06:55 -0800 (PST)
From: "Jaime A. Headden" <>
Subject: Re: New Dinosauricon Taxon Pages: _Therizinosauria_

Stephan Pickering ( wrote:

<Alas, Qilongia's tortuous semanticism obscures the fundamental reality
of evolutionary processes: new species arise from both hybridization and>
mutations (among other factors).>

   Aside from ignoring my recent posts on this subject, has also refused to pay attention to any form of
professional modicum in regards to dealing with scientists and data, which
got suspended from the DML. If continues to harrass me here, then I will seek to
further inconvenience's aggressive dissemination
of science. Anyone familiar with the DML in the last week will be quite
aware of this. If is not civil here as he was
there, where the rules against _ad hominem_ forbade his attitude, then
fruitful discussion is impossible.

<Natural, not experimental, hybridization is a fulcrum of much speciation,
as the work of R.G. Harrison explicates.>

   Problematically, the observation of natural hybridization is a work of
theory, as to prove hybridization requires control experiments. The
subject is innately connected to the observer/scientist. If knows of a way, or any one else, for that matter,
to show how hybridization occurs outside of man's ken that is not in fact
a form of natural non-hybrid speciation or mutation with reversals or
convergence (happens a lot in the land bird and viperoid speciations ---
there's only so many things you can do to a crest, beak, fang, or maxilla,
for instance).

<Such successes, by definition, are fertile F1 progenies (contrary to what
  many may think, hybridization is not uncommon in "nature"), i.e., are the
  offspring of matings between individuals of two populations, groups of 3+
  populations, these offspring passing synapomorphies to further

   This data comes from plants, which have a genotypic plasticity rather
above that of animals. Nearly all hybrid species of animal, whether mammal
or bird, are infertile except with a parent species. Best such example is
the mule: *Equus caballus* x *Equus assinus*. A female mule can mate with
a horse stallion, but not a donkey jack; the converse is true: a male mule
can only mate with a jenny donkey. This does not permit a population of a
hybrid species to occur. For plants, the hybridization of a population
into another is exactly what I referred to as a possibility of
distingusihing this form as a different species, for communicative
purposes. There are different definitions of hybrid species as well, and
rather than propose others, this one is being contradicted? Data, anyone?

<A final note: it is premature to establish Therizinosauria, a
phylogenetically redundant name (the goal of phylogenetic systematics is
clarity, not obfuscation).  The ongoing plethora of redundancy, as it
relates to post-K/T Theropoda ( i.e., "birds"), is in the long overdue
process of being revised on the principles of anatomical analysis and
phylogenetic systematics by Bruce Livezey.>

   Since therizinosaurs have little to do with birds, this is pointless.
However, use of "Therizinosauria" has very real circumstances involving
names not covered by the ICZN (therefore priority is not an issue) and
phylogenetic taxonomy as laid out in the various publications of de
Quieroz and Gauthier (1991, 1992, 1994, 1998, 2001). The name
Therizinosauria, though using *Therizinosaurus* as an eponym, has little
to do with *Therizinosaurus* itself but rather the entirety of a group
whose relationship to one another is undeniable. The same is for
Segnosauria, an earlier name that, on the basis of structure, cannot be
compared (as per Keesey's discussions) to Therizinosauria. If it were
defined, it should be defined separately from Therizinosauria, perhaps as
a stem containing all therizinosaurs. Thus, the name is not redundant,
just unaware as to definition and content. As pointed out by Keesey, at
the times it was used, though used concurrently by Maryanska in 1997, the
name does not compare to Therizinosauria Russell, 1997. Just sad it should
have been named.

<Therizinosaurus itself is barely diagnostic if one ignores the suite of
characters found in other, more complete taxa>

   So says one who not only has a lack of awareness of the literature, but
a lack fo awareness of the material. *Therizinosaurus*, as establish by
Maleyev, has at least three autapomorphies in its claws that differentiate
it from all known therizinosaurs. This includes relative taper and
curvature of the claw "blade", shape of the claw in section, and shape and
position of the flexor tubercle. Those familiar with therizinosaurs and
not what other people say about them, have no trouble in recognizing *T.
cheloniformis* as a unique animal. Perle's work in 1974 referred a large
arm with two other specimens of claws to the hypodigm on the basis of
joint retention of these ungual features, and this supplements the
identity by features of the carpus, metacarpus, humerus, and ulna, all of
which are unique as yet to *Therizinosaurus*. Similarly the type contains
ribs of a dimension and shape not yet known in other therizinosaurs except
for the more "curvy" and broader ribs of *Alxasaurus*. *T. cheloniformes*
is far from un-diagnostic.


   Jaime A. Headden

Jaime A. Headden

   Little steps are often the hardest to take. 
We are too used to making leaps in the face of 
adversity, that a simple skip is so hard to do. 
We should all learn to walk soft, walk small, 
see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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