[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Syntarsus feathers



Jaime A. Headden wrote-

>   These are not what spinal tables are. Note that the spinal table is the
platform, pretty much
> level, at the base of the neural spine, between the zygapophyses. The
distal end of the neural
> spine is what Rob Gay is referring to. The "t-shaped neural arch" is a
confused statement of a
> distally transversely expanded neural spine, which is seen in animals that
bear paramedian dermal
> ossicles; this includes Ceratosaurus, aetosaurs, crocodilians, etc.

I disagree.  A spine table is a structure formed by the distal transverse
expansion of a neural spine.  Note a few quotes from Makovicky's (1995)
thesis on coelurosaur vertebral morphology-
on Microvenator- "The spine is not expanded into a spine table distally,
..."
on Avimimus- "The distal end does not expand into a spine table."
on Saurornitholestes- "The tip bears a moderately expanded spine table,
which is
proportionally smaller than in Deinonychus."
"Dorsally the cervical neural spine is expanded into a spine table."
on Archaeopteryx- "Each one has a straight dorsal edge that is not expanded
into spine table."
on Ornitholestes- "The distal end is more expanded lateromedially than it is
at midheight, but it does not form a true spine table."
Finally, a character from his phylogenetic analysis-
23. Distal end of dorsal neural spines not transversely expanded = 0.
Distal part of neural spine expanded to form a "spine table" = 1 (Gauthier,
1986).

Rob Gay wrote-

But also present in phytosaurs and aetosaurs. How well developed are they in
those two groups that you mentioned as opposed to known armour-bearing
animals?

I couldn't say, lacking any good references on crurotarsans.  Deinonychus
does have better developed spine tables than Ceratosaurus though.

Mickey Mortimer