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R: Spare ribs?
regarding sacral ribs/transverse processes, you may find of some interest
the drawing of Edmarka's (i think) sacral bertebrae(fig 3 C-D-E) in
"Megalosaurid Dinosaurs from the late Jurassic Morrison Formation of eastern
Wyoming", by J.D. Siegwarth and others that can be read online at
While S1 is depicted as not bearing any Sacral Rib , but only its
Transverse process, other sacral vertebrae(2-5) have both ribs and trans.
>From what I see from the picture(have't read the paper yet, sorry) they're
fused to one another(rib-tran.proc).
In Sinraptor attachment scars for sacral ribs only are found on the medial
side of ilia( there's no indication of the attachments sites for the
transverse processes);however in Allosaurus there is a clear separation
between the attachmente sites for tr.prs. and ribs(Madsen pag.147).
Madsen clearly depicted sacral ribs and transverse processes on sacral verts
as separate structures;interestingly the fifth sacral vert. bears a big rib,
while the fifth sac. vert. in Sinraptor is considered as having a
transverse process, but no rib.
Other sacral verts in Sinraptor are poorly preserved(excluding the first,
almost completely preserved, missing only the caudal portion of centrum ,
neural arch and spine, but bearing a transverse process and no rib, as in
Edmarka but differently form Allosaurus in which a "vestigial"[doesn't seem
to contact the iliumat least ] first sacral rib is present), so it's not
possibile to know what the condition was like in this beast.
Fig. 12-B in the above mentioned reference(Megalosaurid dinos etcetc..)
shows Edmarka's right ilium in medial views so i'm sure that someone with a
more knowledged eye than mine will find the exact position of instertion of
both sacral strucures.
Hope this helps.
----- Original Message -----
From: Mickey_Mortimer <Mickey_Mortimer@email.msn.com>
Sent: Wednesday, February 14, 2001 5:49 AM
Subject: Re: Spare ribs?
Here's what I would like to know- what are sacral and caudal ribs?
> I hear about caudal ribs in relation to diplodocids and some other
> sauropods. Are these just transverse processes? Are sacral ribs
> processes or actual ribs.
> Mickey Mortimer