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Theropod Cervicodorsals and *Monolophosaurus*
Okay, short question.
I don't have the papers available, so I will ask on
the good fortune and aid of the list this plea:
Could someone out there inform me on the relative
condition of the transition of cervicals through
dorsals in *Baryonyx*? That is, cervicals in theropods
tend to be opisthocoelous, then transform to
playcoelous or extremely to amphiplatyan. More avian
taxa appear to possess opisthocoely all the way
through the dorsals, so I'm curious as to the
condition in one spinosaurid theropod.
Also, and I mentioned this to some list members at
SVP: *Monolophosaurus* has the longest skull relative
to its presacral column of any theropod, or in fact
I have made a visual scale up using the figures from
Zhao and Currie (1993) but cutting out each vertebrae
and trying to find the neutral articulation, then
copying the results on a different peice of paper, and
the result showed the short neck (or long skull)
compared to other dinosaurs, and used the measurements
in the same paper to reconstruct aside from that to
determine if, in fact, the neck was so short compared
to the skull. [see below]
The type specimen (IVPP 84019), for instance, has a
skull 67cm long, the complete cervical column length
(including about 10% of the total length to allow for
cartilage and vertebral disc's) is about 60.2cm, minus
the atlas, but that bone doesn't appear to affect the
length of the cervical column when reconstructed as
the occipital condyle fits onto the axis and axial
intercentrum most proximally. The dorsal column
measures an estimated 111.1cm, and total, the skull is
1.113 times the length of the neck, and about 39% the
total presacral column (Zhao and Currie, 1993). Even
*Suchomimus* has a skull only the length (or shorter)
of the neck (Sereno et al., 1998).
skull = 67cm
cervical column (est) = 60.2cm
dorsal colum (est) = 111.1cm
[presacral column (est) = 173cm]
sacrum = 36.7cm [data from Zhao and Currie, 1993]
The first dorsal figured by Currie and Zhao (1993)
may be the last cervical, based on the parapophyseal
position, declination of the diapophysis from the
neural arch, and position of the diaprezygapophyseal
lamina. Currie and Zhao (1993) do not discuss the
vertebral transition, but in addition, the supposed
first dorsal rib bears a strait tuberculum, the distal
articular facet for the diapophysis parallel to the
long axis of the costal shaft, as in the more rostral
cervical ribs, unlike the caudal dorsal ribs, which
have more curved shafts and so the long axis passed
obliquely to the articular face of the tuberculum.
Thus, I suggest the first dorsal is the last cervical,
and the new adjusted measurements are:
cervical column (10, not 9 vertebrae) = 67.6cm
dorsal column (13, not 14 vertebrae) = 103.7cm
The ratio of skull to neck is reduced to nearly 1,
with the neck 6mm longer than the skull, so
technically, it falls within the dinosaurian regular.
One possible solution, though: was the skull
actually a part of the animal to which the vertebral
Jaime "James" A. Headden
"Come the path that leads us to our fortune."
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