Re: "armoured" spinosaurs

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

Stephen Pickering (StephanPickering@cs.com) wrote:

<As far as being functionally quadruped, admittedly  I should have worded
the sentence a little differently: like Iguanodon, Spinosaurus could when
necessary, bear weight upon its front arms, and, for short distances, walk
forward,>

  There is research out and available on the articulation of the forearm
in dinosaurs, supported by various workers including Sereno, Holtz,
Bonnan, and others, where the ulna and radius in no way could rotate or
supinate/pronate relative to each other, forcing the manus to face inwards
(medially). This would have prevented, in an articulated forelimbs as
known for *Suchomimus*, the ability to place that manus on the ground and
in any way bear weight. The only way for the forearm to likely bear weight
was to have the elbow and wrist simultaneously contact or lay upon the
ground, with the humerus vertical, and this would not have gone anywhere
as the wrist could not then bend or flex outward (at this point, the wrist
would _still_ be facing medially) so that the arm would have lifted off
the ground. This would have prevented any ability to use the forearm in
locomotion. It is unsound, except from the original suggestion by Charig &
Milner (1986, 1993, 1997) that the humerus was long and robust enough to
locomote with. Analysis does not support this at all.

<Most of the lost hypodigm of Spinosaurus lacked centra, so trying to
position the neural spines on a hypothetical vertebral column is fanciful,
and Mr Stromer's efforts to guess their positioning in 1915 are just that,
guesses, and I belive it is an unprovable assumption by Mr Mortimer the
best-preserved vertebra illustrated in 1915 is a more caudal dorsal
vertebra.>

  I find this doubtfullness rather refreshing as it allows the flexure of
brain power. But, it is clear from Stromer that _most_ of the vertebrae
from the hypodigm of *Spinosaurus* contain centra. There are only three or
four neural arches that cannot be associated with centra, and one or two
dorsal centra cannot be placed with neural arches, as well as two
fragments of a minimum of two sacral centra (one isolated and one
comprised of the fusion of two sacral centra) that indicate the phrase is
incorrect. As I elucidated earlier, centra can be used to designate
position in the dorsal series. Stromer (1915), as Mickey Mortimer
indicated but did not himself elucidate, indicated that the one dorsal
vertebra with a fused neurocentral suture is apparently the posteriormost
_known_ dorsal, possibly last in the series, because it lacked features
for bearing ribs, as well as infradiapophyseal lamina. There is nothing
fanciful about this.

<It could be that Spinosaurus was a bulky, hump-backed, piscivorous,
narrow-snouted theropod with some cranial dorsal vertebrae being markedly
opisthocoelous. Since 1915/1934,  no skulls and skeletons have been
discovered  with which to re-establish the taxon within a robust cladistic
analysis,>

  Just you wait ... lol ... but no, seriously, the lower jaw alone is
sufficient to distinguish *Spinosaurus* in any analysis, regardless of the
form this takes. It allows analysis of the teeth, form of the jaw, metric
ratios of proportions, and possible ontogenetic implications (such as
possible fusion of the splenial to the dentary) as well as a few other
tricks that have not been remarked previously in the literature. The lower
jaw of *Spinosaurus* appears to indicate an animal with a skull between
5.5 and 6 feet in length, just under two meters. This is plenty big
enough, as it is larger than *Suchomimus*. Another jaw is known from
Morocco (Taquet and Russell, 1998) referred to *Spinosaurus maroccanus*
which appears to indicate a skull over 7 feet length, in excess of 2.25
meters. So this is not just one of Jack Horner's estimates, though this is
maybe where you got it. Jack is privvy to a few secrets as well.

<Drawings for me are not acceptable nor verifiable because the type is
lost.>

  These are carbon-dust illustrations, and I would agree that the artist
who performed them, as was popular at the time, was in excellent shape to
follow the specimens exactly. For instance, look at work in the monographs
popular in England and elsewhere in Europe in the late 1800's where the
illustrations are almost better than bone. Though admittedly, having the
bone is better than anything else; however, in the absence of access to
the bone, which is dust right now, the illustrations must serve, unless
you're supporting the nomen dubium status as a result of the destroyed material?

=====
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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