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Re: Some Comments on *Bahariasaurus ingens* Stromer (1934)



Mickey Mortimer (Mickey_Mortimer111@msn.com) wrote:

<So basically, there is no interpubic foramen, no anterior longitudinal
midline groove, no pubic apron (contra you), it fuses completely anteriorly,
and there are different pubic remains preserved.  Sounds quite reasonable to
me, and from someone who's actually examined it first hand.  More than can
be said for you or I.  Your information regarding the unpublished morphology
comes from unclear photos of the mounted skeleton, in which I can not see an
apron between the bones.  Furthermore, the extent of real bone is
indeterminable from the photo. The ischia may be large for a coelurosaur,
but not for a ceratosaur.  Even tyrannosaurids (Maleev, 1974) and
ornithomimids (Osmolska et al., 1972) have broader pubes than would be true
in Deltadromeus, and that of abelisaurids (Kellner and Campos, 2002) is
broader yet.  If Longrich is right about pubic scraps being present, they
might shed light on the synonymy issue.>

  As pointed out by Darren previously, and as would be obvious in studying pubes
of dinosaurs generally, not every theropod has a pubic fenestra. I also stated
that the pubic fenestra was absent, a feature that in my comparisons is not too
bad to find in the pubes of any theropod, if it was acquired then lost
throughout theropod history; as noted multiple times elsewhere, this is
typically a pneumatic feature and such things can be acquired and lost multiple
times in a lineage, as occurs in the antorbital anatomy of theropods and
archosaurs in general (Witmer, 1997: SVP Memoir 3). Nick Longrich attempts to
point out a form of longitudinal groove as being indicative of pubes, but does
not support this statement, akin but not indicative of the "because I said so"
statement. However, in my earlier post, I alluded to *Dromeciomimus,* an
ornithomimosaur with a cranial longitudinal ridge on the midline of the pubic
apron. Though I'd hate to neigh-say Longrich on this, Sereno has come to an
alternate conclusion, "from someone who's actually examined it first hand."
Before we get into the battle of the experts, while I commented on the possible
points of identity of these being ischia, I pointed out reasons they were just
as, if not more so likely, to be pubes (or ossa pubis, if you prefer). As also
alluded to by Sereno et al. (1996) and in press-releases and on the various
websites maintained by him and crew, *Deltadromeus* is diagnosed by the
slenderness of these elements, and rather than shoehorning a taxon to fit some
idea by "revolutionarily" reassigning material sight-unseen, and based partially
on word of mouth of a public, unsubstantiated claim -- and I think adding a
little doubt into the machine is always a good thing, mind, but not in that
way -- should make us be a bit more skeptical, than to just take a man's word
for it, start using "ischia" in place of "pubes," and deciding this makes the
data superb enough to contradict an alternate placement. Confirmation and
speaking to Paul has confirmed the nature of the composition of the pubis as
listed, then though they consitute multiple associated fragments; as explained
in my previous post, this material when oriented as an ischium differ markedly
in orientation from known ischia with large boots, such as in *Carnotaurus,*
ornithomimids, *Torvosaurus,* and *Elaphrosaurus.* I wrote:

  "[A] rather bizarrely huge ischium, with a distal ischial profile remarkable
identical to that of the pubes of avetheropods, as in distal view (pers. obs.)
the "ischial" boot is triangular in aspect, narrower caudally than cranially,
with an up-turned cranial process of the boot, and a tapering one of the caudal
margin; the angle of shaft to the boot shows that, if an ischium, the point
pointed ventrally with the expanded ventral surface facing caudally ... or it
pointed so that the longer process of the boot, with the "pug-nosed" tip was
caudal rather than cranial[....]"

  Mickey also makes allusions to a photo I showed him a few days ago (the photo
was taken by Ben Creisler, and derives from the old Dinosauricon, for purposes
of credit). This was part of my source material for comparing the pubis in
*Deltadromeus*. I have also seen footage of the mount and until recently had a
lot of other photos available of views of the mount for impersonal examination,
and possibly linked to the recent virus infections I had to switch my email to
avoid. I have also talked to Paul Sereno, in which manner these observations
were confirmed. Though it shoudl not be so circumspect in this manner to suspect
a reasercher of falsifying or "fixing" their work to conform to observations
through photographs, the skeletals drawn by Carol Abraczinkas and Paul were done
with the material at hand, and not though figures of bones; these tend to be
"cleaned" up, as it would be rather tedious to draw all the imperfections,
though eventually this may occur. Many of the illsutrations in work from Paul is
schematic and obviously so, so using these as 1:1 comparisons in favor of
examining the mount or going to Chicago to see the 1:1 casts present there (the
original material is in Morocco) is rather difficult. One reason I tend not to
concern myself with perfecting phylogenies at the moment, as access around the
country is limited and otherwise tends on the favor of others.

Mickey wrote:

<In regards to my statement that the pubes preserve more than the distal boot.]
Perhaps, but exactly how much?  The skeletal also differs from the closeups n
how much of other elements are known (eg. scapulacoracoid, humerus).  I
don't believe it's very trustworthy in this regard.>

  In regards to the material of the pubes, entire portions of the shaft, apron,
and distal end are present as a whole. I also said this earlier. One of the
"ischia" I noted from Stromer (1934) I made allusions to with a largely
protracted proximal edge of the apron, with superficial similarities to the
ischia of *Elaphrosaurus.* If ischia, they would be coelurosaurian, as they do
not appear to possess a puboischiadic plate as in *Elaphrosaurus* and would form
a triangular obturator process; however, again as noted before, elements in the
Baharija are subjected to often extensive distortion, and it is easy to see how
curvatures of shafts and compression can occur; this can easily distort
observations, and so I was skeptical of my own identification. And why I warned
caution in making far ranging id's on plates of material that have been lost for
over 60 years. Yeah, so it makes a lot of comparisons difficult, but that's the
way it is; solve this by going to Baharija and looking for more.

<I still say 1912 VIII 82 is an ischium, regardless of the presence of a
posteroventrally everted pubic apron in some taxa.  The distal narrowness,>

  Which is not indicative of an iliac relationship, or *Carnotaurus* has some
peculiar ischiadic morphology in an articulated and VERY narrow pubes (and it's
a "ceratosaur"!).

<absence of an interpubic foramen,>

  Answered by Darren and above.

<the wider and shorter separation proximally between the shafts,>

  Answered above.

<and the narrow (in lateral view) ilial peduncle all argue for this.>

  Many taxa have narrow iliac peduncles of the pubes, among them
maniraptoriforms. As explained, even the identification of an ischium or a pubis
is ambiguous based on a wierd element. The absence of a pubosichadic plate in an
element compared as a ischium on similarity to *Elaphrosaurus* is questionable,
but evidenciary does not stand when breaking the material down to its
identifications.

I had written:

<<1922 X 48, found near the type of *Bahariasaurus,* is distinct in the slight
curvature of the shape, and the presence of a rather distinct caudal process of
the boot; there is no iliac peduncle, just the facet for the ilium, and in this
it is fairly small. However, only the distal end can be compared to
*Deltadromeus*, and in this it does not appear to be at all consistent.>>

to which Mikey replied:

<I take it you're basing the straight shaft, absent posterior foot and large
ilial peduncle of Bahariasaurus on the translated text?>

  Most of these features are absent in *Bahariasaurs,* though I never said
anything about large iliac (or if a mistype, ischiadic) peduncle. As provided by
me in other posts, Stromer's words only talk about the pubic decurvature or
straightness (I quoted the passage); Stromer (1934) posited that 1922 X 48,
being a "next-door" specimen, may have been conspecific. The appearance of the
specimen, including the lack of any apparent iliac peduncle, is questionable,
but not immediately flasifiable. I used this on the face that, if at least the
two 1922 X specimens are conspecific, they add information on comparisons and
supporting the known material comparable in *Bahariasaurus.* Comments about the
composition and relative use of the material with regards to comparison were
given in my first email in this thread. (I am working on getting a more complete
translation of this section of Stromer's monograph, so that I can track down his
words, but German has changed in 60 yeards and he uses uncommon compounds and
archaic phraseology that make translation difficult.) The holotype pubis of
*Bahariasaurus* lacks the iliac peduncle, as shown in Taf. II,:Fig. 4, where the
surface is significantly illustrated as broken, and apparently missing the
ischiadic pedunculae.

<By "flared glenoid margin"I meant the ventral deflection from the ventral
scapular surface.  As both Baryonyx and Deltadromeus have a laterally angled
glenoid, I don't think its absence in 1912 VIII 60 has much relevence to our
debate.>

  It has a lot to do with this thread as Mickey brought this up to point to 1912
VIII 60 as possibly being a spinosaur, which was heavily part of the last post.
I was refuting this.

<I don't see much resemblence to Carnotaurus, perhaps you would point it out?>

  This had already been pointed out in my post. The same features can be alluded
to these belonging to a tyrannosaur, as the ventral margin is as deflected. The
main criteria for ceratosaur features is in the size of the scapulocoracoid, as
in *Deltadromeus;* one perchance can assume, as I did, that the scapulocoracoid
of 1912 VIII 60 must relate in saze, as it does in tyrannosaurs and
baryonychines, which was alluded to previously. The remainder of the inference
was in the other referred material as being of possible "ceratosaur" affinity; I
was working along this thread.

Mickey finalized with:

<If you don't concern yourself with referred material, why almost exclusively
use referred material to place Bahariasaurus phylogenetically?>

  I never said that I just simply do not concern myself with referred material,
otherwise I would never discuss the other material referred to *Therizinosaurus*
that described the arm in detail; what I recall saying, at least, is that I do
not concern myself with referred material in regards to the synonymy or
application of comparing TYPES and their relevence to synonymy, along much the
same lines as being unable to compare a pubis to an ulna.

  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.

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