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Date: Sun, 02 Feb 2003 16:06:55 -0800 (PST)
From: "Jaime A. Headden" <qilongia@yahoo.com>
To: PhyloCode@ouvaxa.cats.ohiou.edu
Subject: Re: New Dinosauricon Taxon Pages: _Therizinosauria_
Stephan Pickering (StephanPickering@cs.com) 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, StephanPickering@cs.com has also refused to pay attention to any form of professional modicum in regards to dealing with scientists and data, which got StephanPickering@cs.com suspended from the DML. If StephanPickering@cs.com continues to harrass me here, then I will seek to further inconvenience StephanPickering@cs.com's aggressive dissemination of science. Anyone familiar with the DML in the last week will be quite aware of this. If StephanPickering@cs.com 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 StephanPickering@cs.com 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 generations.> 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. Cheers, 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) __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com