Re: Triassic Sauropods

["David Marjanovic" <david.marjanovic@gmx.at>]

> The postcrania of *Opisthocoelicaudia* is classically
> titanosaur, including phalanx reduction, caudal reduction,
> expanded but singular lateral camerae (non-complexity to
> pleurocoels), femoral morphology (wide-gauge hips), etc.
>
> <Not surprisingly, Chinese euhelopodids are basal to both
> Nemegtosaurus and Opisthocoelicaudia.>
>
>   Upchurch finds this a monophyletic non-Neosauropoda group,
> Wilson and Sereno find this a paraphyletic assameblage with
> *Euhelopus* a true titanosauriform (somphospondylian), and other
> "euhelopodids" splayed radially. No concensus.

I prefer Upchurch's view, based on paleobiogeography and

Mathew J. Wedel, Richard L. Cifelli, and R. Kent Sanders: *Sauroposeidon
proteles*, a new sauropod from the Early Cretaceous of Oklahoma, JVP 20(1):
109 -- 114, March 2000

"The presence of of pneumatic camellae has previously been regarded as a
synapomorphy of (*Euhelopus* + Titanosauria) [ = Somphospondyli] (Wilson and
Sereno, 1998) or of Titanosauria alone (Powell, 1987). However, some basal
titanosaurs had a simple, camerate structure (MW, unpubl. data), while the
derived pneumatic camellae have been recognized in the cervical series of
*Brachiosaurus* (see Britt, 1993; Upchurch, 1998) [and *Sauroposeidon*] and
in the posterior cervicals of *Diplodocus* (see Britt, 1993). This suggests
that camellate internal structure is homoplas[t?]ic in sauropods and evolved
in long-necked lineages as a means of reducing weight."

However, I have a different question -- the same paper states

"The cervical vertebrae of *Sauroposeidon* are the longest among the
Sauropoda and, based on comparison to the HM SII specimen of *Brachiosaurus*
[*Giraffatitan*], we estimate its neck to have been at least 12 m in
length -- the longest of any known vertebrate."

I thought that the neck of *Mamenchisaurus*, with its 19 vertebrae, was 15 m
long? Has this been revised?