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Re: Monolophosaurus



I wrote:

<<To clarify, Carnosauria is all taxa closer to *Allosaurus* than to
*Ornithomimus*.>>

and Jonathan Wagner wrote:

<Where did you get this? That's certainly an odd definition, and not
the one I am familar with...>

  Ooops. The opposing anchor was wrong. But the spirit was there, Jon!

  :)

<<Actually, megalosaur-grade tetanuries can be considered basal to
Avetheropoda, making an un-named node, and may include such wonderful
taxa as *Baryonyx* and *Spinosaurus* and the indominatable
*Torvosaurus*.>>

<I find this unlikely. Tom Holtz has recently shared his (a priori)
opinion that "meggie" may be a carnosaur.>

  I didn't mention "Meggie" on purpose. There is a differentiation
between "Meggie" and Torvo, if at least stratigraphically, and if not
morphologically. The pelvises, for one, are very different. (Dealing
with referred material, though.)

<Looking over the illustrations I have has shown that this is indeed
possible. Some of the evidence used to link spinosaurs and
"torvosaurs" (e.g. enlarged claw on manual digit I)>

  I would think this character either plesiomorphic or function
related, or both. [My opinion on the matter; back to the story...]

<has a wider distribution and may not hold up. Spinosaurs are weird
ducks, and may or may not belong where they have been placed.>

  And where is this? I don't have all the lit., so pardom me if I
missed something, but as far as I know, *Spinosaurus* has been put in
every major group of theropods.

<Overall, I think support for the topology you provide may be much
weaker than you think.>

<<In my view, Carnosauria has three grades: sinraptors,
carcharodontosaurs, and allosaurs,>>

<These are CLADES, not grades. I haven't seen any papers which
serously suggest that any of these are paraphyletic (well, ok, maybe
I've seen one suggesting carchars are paraphyletic).>

  Not my point. I was using the sense of these animals in form, not
group, and in the same sense that megalosaur-grade theropods have
their own taxon, though no current diagnosis/definition exists; we use
grade to put a name for the general idea one has when looking at
*Xuanhanosaurus* and *Megalosaurus* in the same picture.

  Sinraptors (Sinraptoridae, etc.) are long-bodied and large-headed;
funny ischia and long neural spines (dorsal, cervical, caudal, sacral).

  Carcharodontosaurs (*Acrocanthosaurus*, *Giganotosaurus*, and
*Carcharodontosaurus*) are giants with small arms and big hands, long
legs, tall neural spines (sound familiar) and very triangular skulls.

  Allosaurs (Allosauridae, whatever, etc.) are slim to stocky, with
big arms and short neural spines, long tails, shorter-than-carch legs,
more rectanular heads.

  All these you simply _see_; they would not require an autopsy to
observe; forms, in other words. Hence, and while I may need to look up
a dictionary, these are "grades".
 
<<all of which have so many similarities they might be included into
one suprageneric taxon.>>

<Indeed, they are already included within several, e.g. Tetrapoda. ;)>

  I meant immediately suprageneric. To jump to Linneus' side, family,
subfamily, tribe, whatever. Whatever will be popularly used to
nominate an immediate-suprageneric taxon.

  I think I just stumbled over my own tongue.

<In all seriousness, given current tree topologies, these taxa
consitute (by definition, until the intrinsic potential for logical
inconsistancy is discovered) the Allosauroidea:

  Allosauridae == { _Allosaurus_ + _Acrocanthosaurus_ }
  Allosauroidea == { Allosauridae + Sinraptoridae }>

  Hey, I have no problem with this.

<<Concensus seems to show Bary as a megalosaur-grade theropod.>>

<Does consensus show that this *means* anything? :)>

  "Grade" may be plesiomorphic, under my usage above. The form is
there, as described in my post.

<< Elongate jaws, [...] corresponding enlargement of the teeth,
nasal/roof of the skull ornamentation>>

<These hardly sound unique to "Mono to Bary and Torvo" as you suggest,
nor have you established if these are truly derived characters.>

  It was not my intention to do so. I'm not making a case for a clade
here. I'm saying that these characters are similar amongst these taxa.
 
<<dentary with great distal enlargement in front of the shallowest
part of the bone>>

<Huh?>

  Another trip. One of the reasons I shy away from writing a character
is in how I actually do it.

   ___ v
  /   \___________
  |   ___         >
  \__/   --________>
       ^

  Try that. The arrows point to the region and general shape I'm
talking about.
       
<<ischium as long as the pubis or nearly so,>>

<Plesiomorphic.>

  My point. It's not derived.
 
 
<<short hind limbs,>>

<Got morphometrics? I know these guys had longer legs than I do. :)>

  Relative to the length of your arms? I did not put that in, did I?
Should have.

  Sorry, Jon.

  Oh, wow, several posts now and I haven't been whooped by Tom yet!

==
Jaime A. Headden

Qilong, the website, at:
http://members.tripod.com/~Qilong/qilong.html
---
All comments and criticisms are welcome!

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