Re: Gallery and Commentary for Copenhagen Mamenchisaurus

[DinoBoyGraphics@aol.com]

>>>Except that rearing in sauropods has yet to be demonstrated or even modeled. 
>>> There is a classic Matt Bonnan post on that subject<<<

Mike and list, a few thoughts:

     Matt is right that rearing as a habbitual feeding behavior has "yet to be 
demonstrated," but this doesn't make it any less likely than the hooverasaurus 
interpretation.  There is this really sad (and totally "undemonstrated") 
asumption that some workers make that a long neck is good for grazing because 
you can stand in one place and not have to move while you eat.  Except that 
everybody who studies locomotive energetics knows that the bigger you are the 
cheaper it is to walk (that is, equal amounts of locomotion consume a smaller 
percentage of your daily energy budget).  It is far more expensive to have an 
insanely long neck your whole life than to simply take three steps any time you 
want to get to new ground fodder, which is why no grazing animals have really 
long necks today (that is, their necks are just long enough to reach the 
ground).

     The energetics viability of a long necked sauropod grazer is just as 
"undemonstrated" as habitual rearing in diplodocids, and while rearing has a 
shot (I would suggest a good one) of eventualy becoming "demonstrated," via 
modeling, viability of the energetics of long-necked grazing likely never will 
be.  

     What's more, while I cannot comment on Steven's SVPCA talk, his SVP talk 
had absolutely no dinomorph modeling of Brachiosaurus, instead it had Photoshop 
manipulations of Janesch illustrations; not exactly confidence-inspiring rigor.

I currently have two WDC Camarasaurus specimens with good necks, and they show 
clearly an upturned keystone-shaped centra in the cervico-dorsal region, 
despite Steven's "conclusion" that Camarasaurus had a horizontal neck.  I have 
not been able to check Brachiosaurus or Mamenchiosaurus, but if Steven's is 
wrong again (and I have no problem imagining such a situation at this point), 
then there is no Fundamental Sauropod Problem, because long-necked sauropods 
either reared or had upturned necks.

I am not claiming that this is "proven" or any such thing, but it's ridiculous 
to cite the anatomically "undemonstrated" nature of habitual rearing while 
ignoring the equal lack of demonstration (if not outright impossibility) of the 
engergetics of long-necked grazers.

Rigor goes both ways

(and now I'm off my soapbox)

Scott Hartman
Zoology & Physiology
University of Wyoming
Laramie, WY 82070

(307) 742-3799