Re: New sauropod refs: Rinconsaurus & Amygdalodon

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

<Calvo, J.O. & B.J.G. Riga, 2003. Rinconsaurus caudamirus gen. et sp nov.,
a new titanosaurid (Dinosauria, Sauropoda) from the Late Cretaceous of
Patagonia, Argentina. REVISTA GEOLOGICA DE CHILE 30 (2):333-353

...

(3) procoelous posterior caudal centra with intercalation of a series of 
amphicoelous-biconvex or amphicoelous-opisthocoelous-biconvex centra. A
cladistic phylogenetic analysis placed Rinconsaurus in the family
Titanosauridae. Within Titanosauridae (Rinconsaurus + Aeolosaurus) is
considered a sister group of the clade (Opisthocoelicaudia + (Alamosaurus
+ (Neuquensaurus + Saltasaurus))). Rinconsaurus caudamirus has preserved
short articulated posterior caudal series with amphicoelous,
opisthocoelous and biconvex centra. This unusual morphology represents 
the first such occurrence in sauropod dinosaurs. From the systematic point
of view, this discovery is important because Titanosauridae were
traditionally defined, among other characters, by strongly developed
procoelia in their caudal vertebrae.>

  And one of the main reasons why I argue the possibility of both caudal
convexity or concavity as well as many other potential and variable
features of vertebrae (such as neural spine bifurcation) in some sauropods
isn't as important as we assume, and cannot be used to account for (or
discount) the phylogenetic relationships of *Opisthocoelicaudia.* This is
in contest to the so-called support for *O.* being a camarasaur;
cladistics being strawman-ned to disfavor the titanosaurian features for
favor of these two, one of which I've communicated on before and is now
the basis of a titanosaur "genus," it should be noted that much of the
support for titanosaurian relationships of *Opisthocoelicaudia* also occur
in the limbs and referrence to pleurocoely form and vertebral pneumaticity
patterns.

<Rauhut, O., 2003. Revision of Amygdalodon patagonicus Cabrera, 1947
(Dinosauria, Sauropoda). Mitteilungen aus dem Museum fuer Naturkunde in
Berlin: Geowissenschaftliche Reihe 6:173-181.

...

  The material includes elements of at least two individuals plus a remain
of another, indeterminate vertebrate, and a posterior dorsal vertebra is
designated as the lectotype of Amygdalodon.>

  Forgive me if I am mistaken, but were not teeth also known and the
source of the designation "almond tooth," and hence, wouldn't the type be
best considered to pertain to that tooth, and vertebrae if diagnostic
rendered to another, if unnamed, species? Kinda defeats the spirit of the
name and reference thereafter.

=====
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.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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