Re: "armoured" spinosaurs

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

Stephen Pickering (StephanPickering@cs.com) wrote:

<If one carefully reads Ernst Stromer's original German papers, it is
clear there is more than one individual being described (as the specimens
are lost, speculations re: another genus are akin to giving taxonomic
status to individual snowflakes), and the elongate neural spines have no
centra. Thus, to say the original type consisted of dorsal spines cannot
be proven.>

  This is bunk.

  If one reads the paper carefully enough, one will find that 1) Stromer
found all the elements scattered in a quarry, but that there were no
overlapping among elements, suggesting to him that they can all be made a
single catalogued specimen, and 2) that there were at least two vertebrae
with fully fused neural central sutures, especially one of the tallest
vertebrae in the series. All centra can be formed in a series of relative
opisthocoely and development of the cranial convexity, which in theropods
decreases towards Coelurosauria from the basal tetanurine condition, so
that more basal tetanurines (e.g., *Torvosaurus*) have the most
opisthocoelous dorsals and all cervicals are opisthocoelous, then
decreasing in humber to only cervical or anterior cervical opisthocoely.
Even this is lost. Study by yours truly from examination of the figures
and form-matching of the elements and fragments indicates that 1) there
are three further sets of centra and neural arches that can be paired up,
though the neurocentral sutures are open, and that 2) the dentary/splenial
and centra of the vertebrae are easily of a size comparable to *Baryonyx*
or *Suchomimus*, further supporting their inclusion in the same probably
individual. Stromer is easily justified in declaring *Spinosaurus
aegyptiacus* as a valid nomen with a valid holotype. The caudal vertebrae
suggested as ornisthischian by Norman in 1990 (The Dinosauria) does not
hold water as it is clearly theropodan based on the hollow centrum
(Stromer, 1915; pers. obs.) and is incomparable to the condition seen in
such carnosaurians as *Allosaurus* or *Acrocanthosaurus* that it cannot be
justified as a probably *Carcharodontosaurus* caudal. The vertebra also
differs sufficiently from *Deltadromeus* to defy referral. So it, in all
likelihood, even though Stromer suggested it was too large for the
holotype (I disagree) belongs to the type. Even so, the vert more than
likely belongs to *Spinosaurus* based on comparison with *Suchomimus*,
with which it shares a good deal of features.

<In fact, both Spinosaurus and Spinosaurus B, as Mr Stromer presented
them, appear to be a disrticulated hodge-podge of elements.>

  *Spinosaurus* B was based on a cervical vert and associated material
that have since (Sereno et al., 1996) been referred to
*Carcharodontosaurus*. Also see Russell, 1994, in _Comptes Rendus_ for
clarification of other possible *Carcharodontosaurus* material from
Morocco, a discussion of the *S.* B material, and comments between both
cited papers on the status of a possibly valid *Sigilmassasaurus* taxon.
*Spinosaurus* B is _not_ to be confused with *Spinosaurus maroccanus* for
which Russell erected an entirely different vertabra as the type.

<To state, as Jack Horner has done, that Spinosaurus probably had an eight
foot long skull is based upon no known evidence,>

  :) no comment ... but ... no comment.

<as is his idea the animal was 19 feet 7 inches  high (including the
"fin") and 43 feet 9 inches long.>

  Based on comparison with *Baryonyx* and *Spinosaurus*, this is a _low_
estimate. The type was not even fully grown, based on the open
neurocentral sutures.

<Coupled with this is the unfortunate use of "Spinosauridae" in various
cladistic analyses, a nomenclatural chimera, as Spinosaurus remains a
nomen dubium>

  In whose eyes? By last count, all researchers on spinosaurids have
supported the validity of *S. aegyptiacus* and especially that *Baryonyx*,
*Suchomimus*, *Spinosaurus*, and *Irritator* form a monophyletic group.

<(along with Therizinosaurus).>

  Instead of being impolite, I'd like to say that no other fossil claws
have been found in the record except for that connected to the arm in the
same level years later that support the nature of *Therizinosaurus*, along
with the type dorsal ribs, which most people seem to follow the later
dismissal as sauropodan because they were flattened mediolaterally (as in
*Alxasaurus*).

<Of interest are the relationships between Baryonyx and  Suchomimus:  taxa
having long forearms, narrow snouts equipped with non-serrated spike-like
dentition.>

  Except that both these taxa have serrated teeth, the ulnae bear
diagnostic olecrana, the snouts are broadened at both maxilla, premaxilla,
and dentary rostrally to form a rosette, and the teeth number seven unlike
all other theropods except *Pelecanimimus* (*Irritator* also has such a
dentition, but unserrated, like *Spinosaurus*). There are numerous other
features used to diagnose Spinosauridae, and Baryonychinae, as supported
by Sereno et al., 1998, but you do not have to use that resource. The list
is rife with discussion on the diagnostic features of Spinosauridae and
its subgroups. Look especially for discussions on *Suchomimus* between
Marco Mendez and myself in 1999--2000 and as well as in 1998 upon its
discovery that remarks on the possibly synonymy between *Suchomimus* and
*Baryonyx*.

<Rather than a "fin", these animals may have looked more like hump-backed
bison.  (I am here, I hasten to add, borrowing freely from Jack Bailey's
fine 1997 paper on these taxa, and thank Jack for his penetrating 
insights.)>

  Penetrating, but not thourough. Dr. Bailey's comments have also been of
great fuel to discussions on this list. "Hump vs. Sail" in the archives
will certainly elucidate various listmembers comments on this subject.

=====
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.

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