Rhoetosaurus

[Adam Yates <zooamy@zoo.latrobe.edu.au>]

While spending a day in Brisbane recently, I had the chance to see some 
of the dinosaur material in the Queensland Museum. I was particularly 
interested in checking first hand wether Rhoetosaurus really had forked 
chevrons or not. Upchurch had rejected Macintosh's placement of 
Rhoetosaurus in the Shunosaurinae (Euhelopodids in Upchurch's 
classification) and cast doubt on its possesion of forked chevrons. 
Well, though most of the chevrons were too broken and eroded to be of 
use, one pair showed without doubt that they were forked. So was 
Rhoetosaurus an Australian Euhelopodid? Upchurch stated that the lack of 
a bridge of bone across the proximal ends of the anterior chevrons was a 
Neosauropd character that excluded Rhoetosaurus from the 
Euhelopodidae. This leaves a number of possibilities 1) Rhoetosaurus is a 
diplodicoid, 2) Rhoetosaurus is an Euhelopodid and adherant matrix is 
obscuring the details of the proximal ends of the chevrons (a bit of 
preparation wouldn't go astray) 3) forked chevrons are primitive for the 
Eusauropoda at least. If this last scenario is correct then hypotheses 
regarding forked chevrons as specialisations for a tripodal feeding 
stance are likely to be incorrect.

Adam Yates