Re: Revising Hou et al, 96 (woo-o-o-o-o-o-o doggy!)

["Jaime A. Headden" <qilongia@yahoo.com>]

Mickey Mortimer (Mickey_Mortimer111@msn.com) wrote:

<You keep changing what you say you're writing about.>

  I have maintained one theorem during this entire discussion: ambivalence
of character support for *Sinornithosaurus* as an avialaean. I will
continue with a refutation of your features supporting *Sinornithosaurus*
as avialaean as refutation of your interpretation of its anatomy. This is
below.

<1. I listed the elongate prezygopophyses and chevrons of Sinornithosaurus
as one of the characters Xu et al. (1999) used to assign it to the
Deinonychosauria, but said this was also found in Microraptor, "which is
even more bird-like (but still thought to be a deinonychosaur by many)."
2.  You replied by saying yes Microraptor is thought by many to be a
deinonychosaur, and "for many other reasons, including the pes
construction (an apparent troodontid + dromaeosaurid synapomorphy, along
with pedal digit II features)."
3. I replied that these "deinonychosaurian" pedal features are "also found
in Rahonavis, a probable avialan."
4.  Now, you become confused.  You cite my quote above as being in regards
to "elongated rostral chevron processes", which it wasn't.>

  Uhm, err, no I didn't. My statement above (now deleted) was in direct
reference to "pedal characters", nothing more. I wrote very little (if
any, as I recall) about the tail in any of these animal. Elongated
prezygapophyses with forked cranial ends and a medial facet for the
preceding postzygapophyses coupled with chevrons bearing elongate cranial
processes that are similarly forked and form "crimped" bundles as far
cranially as the first few caudal vertebrae are distinctive, though.
Thanks for refreshing my memory ... and sincerely, appologies if I
confused you, but I was staying very true to each comment's origin, not to
refer to different subjects.

<After this you reply that they are present in Rahonavis "Too a much
smaller degree.">

  I never said anything about *Rahonavis'* tail ... are you sure you're
not confusing me with David? What I have to say about *Rahonavis* will
come later....

<...>

  Cut that part out because it refers to things I never said....

<5. Finally, you say you were talking about the caudal metatarsal flanges,
directing me to you "very previous paragraph", when in actuality you did
not bring those up until the very end of your post,>

  Confusingly, I was hoping this would indicate the last paragraph of my
previous post, which was, to quote, my "very previous paragraph." Sorry.

<A. Elongate caudal prezygopophyses and chevrons are a possible
deinonychosaur character of Sinornithosaurus, assuming Microraptor is also
a deinonychosaur.  However, if (as in my phylogeny) microraptor is an
avialan, they tell us little about Sinornithosaurus.>

  And because your phylogeny does not include *Sinovenator*, I will for
the moment disregard it as ... outdated. However, presently,
*Sinornithosaurus* and *Microraptor* affinities are weighted by their
number, rather than any feature on it's own. These, as I attempted to
show, are (1) not found in Aves proper, are (2) found in *Archaeopteryx*
but not in Pygostylia, and are (3) possibly plesiomorphies of Paraves
generally, a contention supported in both Xu and Wu (2001) and Xu et al.
(2002). [Yes, I finally found I actually had Xu and Wu (2001) (thanks for
the help in recovering that, Mickey).]

<B. Rahonavis has a more strongly developed sickle claw than Microraptor,
so sickle claw characters are very poor evidence for deinonychosaurian
affinities in the latter taxon or Sinornithosaurus.>

  At some point in the past, I suggested that claw morphology in the
sickle-clawed dinosaurs were possibly functional to effect, and would play
little, if any, phylogenetic part.

<C. Caudal metatarsal flanges are found in Sinornithosaurus and
Microraptor, but also in Archaeopteryx (Paul, 2002) and possibly
Rahonavis.  These are thus also poor indicators of deinonychosaurian
affinity. Whew!  Glad we got that cleared up....>

  And back to my refutation, which was ignored, I guess, that
*Archaeopteryx* does not have the caudal metatarsal phalanges, in any
metatarsus I've seen (I have photos of each specimen) that _would_
indicate that, except to compare the caudal convexity of the outer and
inner shafts. This is seen in many bird metatarsi, including *Avisaurus*
and many other enantiornithines, much more derived than seen in
*Archaeopteryx*, and are probably not flanges but simple ridges on the
exterior corners of each shaft. I said this before.... Any ambiguity makes
a _bad_ usage of the qualifiers "poor" or "good."

<I'm also using a length/height ratio (ventral edge vs. subnarial
respectively), not a premax length / skull length ratio.>

  Uhm, I was not saying you were using a length ratio, I was saying this
might be a good ratio to look at. I was wondering if you were using a
premax height (supranarial) to length, at which point using my own
figures, we get two different comparisons.

<Oh come on, you don't seriously expect a nice smooth curve of values for
a character like this, with Sinornithosaurus' being taller than
Archaeopteryx's, which are taller than Sinornis', etc.?  And while
confusiusornithids have very modified beaks, Protopteryx, Sinornis, the
Spanish nestling, Eoenantiornis, etc. do not.  Therefore, there is no
reason to suspect convergence.>

  Yes, I do expect a nice smooth curve. Otherwise the character is too
"lumpy" and possesses too many anomolies for effective use. Were it that
life were binary, but even a gradational model is not apparent, as each
taxon appears to affect the position of the nares or premaxillary
subnarial depth (which is relative to tooth-root length) differently.
Providing a commonality to each level higher into birds, and maybe I'll
agree with you, but I see this as functional variation. As I said,
ornithomimids have modified snouts, each dromaeosaur varies on its own, as
do troodontids, and this cannot be used as you do. I think the wheat was
lost in the chaff....

<Even if a character is definitely very homoplasious, it should not be
removed from a matrix.  There still may be subsets of the apomorphic taxa
that truly share the character, like ornithomimosaurs + alvarezsaurids for
instance.>

  Size-related characters are homoplasious, as is the very condition of a
ziphodont tooth morphology. Would you leave or have these in your matrix?

<Unknown for all three, but it doesn't matter.  We don't have to show the
presence of a character in intermediates to use it as a synapomorphy
between two taxa.>

  It is for there to be any lack of refutation. As I said, intermediates
are important for asserting gradation. *Archaeopteryx* lack rib facets, as
even do other maniraptorans sans birds. That the nesting oviraptorid
(refered to *Citipati* on the basis of unpublished data) and
*Velociraptor* (fragementary sternum with three broken "ventral ribs" on
one side, and none actually touching the sternum itself) do not show, in
the absent of actual facets on the sternae, the actual number of sternal
ribs.

<I said "with each sternal plate being longer than the sacrum and
supporting about five attachments for sternal ribs", not that they were
neccessarily correlated.  I was just correcting your statement that
Sinornithosaurus "doesn't have much in the way of sterna".  Point is
Sinornithosaurus and basal birds have more than three sternal ribs, while
Velociraptor and Citipati do not.  Also, Microraptor has four pairs.>

  And *Bambiraptor* has five facets reconstructed, but the elements are
said to be in very poor condition. My point was that this value may not be
of any phylogenetic utility. Both troodontids and ornithomimosaurs have a
hollow parasphenoid rostrum (*Sinornithosaurus* is said to as well) but
*Sinovenator* does not; it's still useful for troodontids unto themselves,
as for ornithomimosaurs. Spinosaurs and the basal ornithomimosaur
*Pelecanimimus* have seven premaxillary teeth, another character that is
meaningless to coelurosaurian phylogeny. Your contention that "if any two
taxa have it" must be considered on the phyletic space in an anlysis. If a
character contributes no information, it should be culled. This does not
mean it cannot be included for later analysis. But presently, in theropod
systematics, the robust-gracile dichotomy is not diagnostic to taxon and
cannot be used for phylogeny as shown by Colbert, Raath, and Padian and
Gauthier.

<So your theory is that terrestrial taxa will have more robust fibulae
than arboreal/scansorial ones?>

  I said nothing about fibulae. Fibulae may become reduced not as an
arboreal function but as a relation to tibial compression; the presence of
a single element in the shin that effects the autopodium decreases splay
during the compression phase in a walk. Cursors will either loose the
fibula, or fuse it to the tibia; this is also seen in many primates (e.g.,
*Tarsius*) which have elongate metatarsi are are "leapers" (they will hit
the substrate with all four limbs, but for purposes of manipulation, the
forearm retains it's supinatory ability). Theoretically. It is
corroborated in metapodial fusion in many leaping rodents. As a parallel,
more robust limbs occur in larger sciuromorph rodents than smaller, where
the smaller are arboreal and the larger are terrestrial/fossorial.
Plesiomorphies apply in some groups, but this is good contentions that
many rodents who are scansorial are the more primtive, ancestral ones, and
recent fossils appear to support this (not just *Eomaia*).

<Perhaps you're right.  In addition to possible measuring problems (this
was from my old character list), there may be a behavioral link.  Some
highly cursorial taxa have robust fibulae though (Gallimimus, Avimimus,
etc.).>

  *Avimimus* does not have a robust fibula. The distal end is fused to the
tibia and tarsus ... the proximal end is reduced and at one point it was
conjectured (Norman, 1990, I think) that the fibula was in fact in two
parts, the proximal caput and the distal fused portion. They are probably
one element, and it is very, very slender. Ornithomimosaur and tyrannosaur
fibulae are fairly sturdy, not as expected in many avian and quadrupedal
cursors, but this may be related to other mechanical effects and may show
that they were not truly as cursorial as previously shown. They would
permit ease of twisting in the lower limb, and this is destructive to
tibial compressive forces during the walk-run phase.

<Also, it's odd that such probably secondarily flightless taxa as
Sinornithoides and Microvenator retained gracile fibulae, while
Velociraptor and Caudipteryx redeveloped robust ones.>

  Err, not if you think of them as terrestrial grade compared to arboreal
forms. I accounted for this, actually. Oviraptorosaurs, oddly enough, have
slender fibulae, and that of *Caudipteryx* is more slender than other
forms. I would like to know what you call a slender fibula if you consider
that of *Caudipteryx* to be robust.

<So you were referring to the mandible (I was thinking of the lateral
quadrate process, oops).  I would counter with the fact that while some
basal birds (eg. Gobipteryx) have a strong lateral mandibular process,
they still only have two distal quadrate condyles.  Thus, the two
characters are not conditional.  Indeed, Clark et al. (1994) state
Erlikosaurus' third quadrate condyle does not articulate with the
mandible.>

  And that of *Sinornithosaurus* is completely unique to it, unlike the
third condyle in avian jaws, or *Erlikosaurus*' extra apparent "condyle."

<"The condyle, or the shaft? I see the element is rather flattened in
aspect, but this does not appear to be the same in pygostylians, which
expand the shaft proximal to the distal terminus (condyle). Archaeopteryx
lacks it, however, as does Microvenator.">

  But the second metacarpal is known, as is ... apparently, the first
phalanx of the second digit. Which lacks the flange. I may be wrong, but
there is no apparent flattening.

<But we're talking about MANUAL phalanx II-1, not pedal phalanx II-1.
Remember, you were just talking about the manual phalanx being flattened
in pygostylians.  Regardless of whether you meant Microvenator or -raptor,
neither has a described manual phalanx II-1.>

  We were talking about both.

<Okay.  Why did you suddenly switch from manual phalanx II-1 flattening to
pedal phalanx II-2 proximoventral heels?  Why did you state Microraptor
lacks a flattened manual phalanx II-1.  Do you have an early copy of the
new AMN description of Microraptor?>

  We were talking about both.

<I agree that neither side is obviously correct at this point.
Sinornithosaurus could be a basal deinonychosaur, but I feel the evidence
for it being a basal avialan is at least equally strong.  Sinovenator does
influence a few of my characters, but not all.>

  Have you fully coded it?

  I will pause here as I work retrograde and grab some back posts. Big
thingie on *Sinornithosaurus* coming up....

  Cheers,

=====
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.

__________________________________________________
Do You Yahoo!?
Yahoo! Health - your guide to health and wellness
http://health.yahoo.com