Re: Sauropods Size

[<TWILLIAMS@canr1.cag.uconn.edu>]

George Olshevsky wrote:

> Largest sauropod overall: Amphicoelias fragillimus
> This is the largest dinosaur ever described in the scientific literature. 
> Trouble is, the only known specimen is a huge partial vertebra (a neural 
> arch--the upper part of a vertebra: largest such fossil ever described) that 
> is estimated, when complete, to have been more than two meters tall. This 
> fossil was extremely fragile (very thin bony laminae) when Cope described it 
> in 1878 (hence the species name: and we need the species name because Cope 
> also described smaller species in the genus Amphicoelias),

McIntosh (1990) regarded _Amphicoelias_ as a suspect genus, and based 
upon the poor quality of the material known for the genus at the time, 
that's no real surprise.  There was a presentation at the 1996 SVP 
meeting regarding new _Amphicoelias_ material - all I've seen is the 
abstract (Wilson and Smith [1996], J. Vert. Paleontol. 16(3):73A).  

Wilson and Smith mention a partial skull, 12 presacrals, 7 caudals, 
pelvis, and femur, all from the same individual.  They regard 
_Amphicoelias_ as a basal diplodocoid (i.e. outside the 
diplodocid+dicraeosaurid clade).  Wilson and Smith refer the new 
material (from Park County, Montana) to _Amphicoelias_ on the basis 
of femoral characters. 

As I understand it, most of the knowledge of this genus comes from 
_A. altus_, not _A. fragillimus_, and I don't know to which species 
Wilson and Smith refer the new material.  I have seen _A. altus_ 
listed as a junior synonym of _A. fragillimus_.  Does anybody know 
why _A. altus_ is referred to the genus _Amphicoelias_? 


Tim