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Re: Protoavis is part pterosauromorph, no details about Novacaesareaia, etc.



Mickey Mortimer (mickey_mortimer111@msn.com) wrote:

<Thankfully, Jaime realizes that he has also formed opinions based on written 
and illustrated data instead of personal examination and presented them on his
website.>

  My observations are not limited to publications, actually, but while I have
viewed some specimens personally, most are treated from photos viewed
personally. So yes, I have personally examined several fossils. A few
exceptions include using Jain and Bandyopadhay's *Titanosaurus colberti* paper
to draw a skeletal diagram, and Benton's *Scleromochlus* monograph to draw a
skeletal diagram; these being largely limited to skeletons, I figured they as
pieces in continuous progress based on published data speak for themselves and
thus I should not need to defend them, since I am literally my own harshest
critic. Since the website in question (http://qilong.8m.com/) has a disclaimer
about the utility of the data and my sources and all references used are
listed, I am also on stable ground as to changing data. Similarly, unlike
Mickey, I do not have "opinions" formed on these data, but follow data until
there is no more data; hopefully, I will be dead before there is an end to data
that can be gleaned from the fossils I hope to study.

<Where were you to chew out Scott for using the term 'silesaurid'?
http://dml.cmnh.org/2005Aug/msg00175.html>

  Offlist, actually. Though admittedly in my reply to Scott Hartman publically
on this topic (http://dml.cmnh.org/2005Aug/msg00232.html) I used "silesaurid"
once in quotes and once without. Scott is aware of my sticklership and I felt
he was professional enough to slide (especially as the Science Director for the
Wyoming Dinosaur Museum). If any taxon is applied of late with a stem like -id
on the end, this usually applies to an -idae, yet neither does one exist nor
does it seem reasonable yet to use it until such a clade is diagnosed to allow
reference of taxa to this group.

<And for that matter, what's the reference for anything being incontrovertibly
a member of any clade?  Or is this science?>

  Metataxa are a figment, in my opinion, of the observer's imagination. I also
think there should be diagnostic reasons to refer a taxon to a clade, and that
if all life is united in levels of increasing community among taxa, then these
levels of community can be cladistically formulated, forming "clades". Thus all
taxa belong to clades. This is theory, however. Certainly there are taxa that
seem difficult to place. I am right now of the opinion that some of these
simply show ghost lineages time will resolve (placodonts are a good example, as
are ichthyosaurs, and even *Doswellia* and such taxa like *Protoavis* will
eventually find agreed-upon "homes") as we find new specimens, but that general
conclusions can be made. *Silesaurus* for example is unlikely to be anything
but a member of Dinosauromorpha by both diagnosis and definition, so it is a
member of a clade. By definition and diagnosis, it may not be a member of
Dinosauria or any subgroup thereof. For me, any "Silesauridae" is just another
clade with another definition and/or diagnosis. Thus, scientific equality.

<In any case, I agree with Irmis, Nesbitt et al. that Eucoelophysis is a 
'silesaurid' after comparing the photos in its description with the figures of
Silesaurus.  The femur is especially convincing, as Silesaurus shares
Eucoelophysis' supposedly apomorphic proximal groove and is nearly identical in
shape.>

  *Eucoelophysis* Sullivan & Lucas (1999) as I recall, was applied to the
Ceratosauria largely on the basis of the caudally-backswept diapophyses of the
dorsal vertebrae, a feature unknown in *Silesaurus* (Dzik, 2003). 

  In addition, the tibia of *Silesaurus* possesses a fibular crest, while that
of *Eucoelophysis* does not, as far as published descriptions go, though the
crushed *Eucoelophysis* material is a far cry from the relative perfection of
the *Silesaurus* quarry. Admittedly, the scapulae are nearly identical, and
while the femora both possess a mediolateral sulcus the breadth of the femoral
caput's dorsal surface, in *Eucoelophysis* the anterior trochanter is a tall
crest without a lateral or medial shelf, while in *Silesaurus* this crest does
not rise higher than the lamina that connects it to the femoral shaft further
proximally on the femur. Additionally, the morphology of the *Silesaurus* femur
otherwise indicate a far more primitive condition in the fourth trochanter as a
larger structure than as a triangular lamina as in *Eucoelophysis*. Femoral
curvature is inferred, not actual, since the femur is in two pieces, the distal
half of which is flattened obliquely -- but, unlike *Silesaurus*, the fibular,
lateral condyle of the distal femur projects with a dorsal shelf. Taphonomic?

  Furthermore, *Silesaurus* seems to possess many more plesiomorphies relative
to the Theropoda, Saurischia, and even Dinosauria, that restrict it compared to
*Eucoelophysis* which, unlike *Silesaurus* seems to be much more likely as a
primitive theropod. This data, of course, is independent of the dorsal capital
sulcus of the femur shared between the two. The pubis of *Eucoelophysis* bears
a larger pubic foramen than in *Silesaurus* based on the preserved curvature
and diameter, though this is indistinct based on lack of preservation of the
entire obturator plate. The referred pubis, AMNH 2706 (a paratype of
*Coelophysis longicollis*) seems however MUCH more consistent with *Silesaurus*
than that of *Eocoelophysis*, and the proximal ischioacetabular "notch" is
virtually absent if not an artifact of perception, limiting its reference to
the type pubis. The curvature of the shaft, absent in the type, and the shape
of the proximal end given the acetabular margin and iliac peduncle, are
virtually identical to *Silesaurus* and this is less so than in
*Eucoelophysis*; the primary differences seem to be the presence of a pubic
boot and less angulation in the proximal facets of the pubis in the latter. The
type femur of *Eucoelophysis* shows, relative to *Silesaurus*, an angle of
greater than 90 degrees between iliac peduncle and acetabular margin, rather
than less as in AMNH 2706 and, for example, ZPAL Ab III/361. But since this is
all based on two papers, and not on personal examination, this is all very
speculative, and we have not seen Nesbitt et al.'s data on the subject, but
until then, the proximal groove doesn't resolve the position of two taxa in my
book without a more extensive comparison and supportive data between two or
more taxa. The rest of the data that I can see to refute this argument seem to
support a plesiomoprhic use for the proximal groove.

  Cheers,

Jaime A. Headden

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


        
                
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