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Fwd: Long Necks (was Sauropod ONP)



Here's Mark's post:

Back to informed  speculation again, but I think that the long-term success 
of the sauropods as a  group could have been a result of (no pun intended) 
their flexibility, both  environmental and anatomical. Although from the more 
recent studies (Retallack,  1997, Foster, 2003), based on paleosol analysis and 
taxonomic frequency Morrison  (and possibly Tendaguru) diplodocoids and 
macronarians seem to have had broad  habitat preferences, both types existed in 
a 
large geographic area that  apparently swung between mild seasonal aridity and 
wet, humid conditions for  long periods of time. If this was the case, local 
abundance and availability of  plant food items would also be affected. 
Together 
with their worldwide  distribution and prevalance over most of the Mesozoic, it 
suggests sauropods as  a group had to be adaptable in their diets. They 
probably couldn't specialize  too rigidly on any one food source, and for too 
long 
a period of  time.

This is where long necks were a great adaptation. If the  "horizontal sweep" 
feeding mode was effective in garnering such ground forage as  ferns, aquatic 
vegetation and other low-growing forms during the season(s) when  these were 
abundant, it could also have meant survival in the times when these  were 
scarce, and the tallest conifer and ginkgo foliage/ fructifications/bark  may 
have 
been best, or perhaps only accessible, by reaching way up-- not only  
quadrupedally, but if necessary, bipedally and tripodally as well in the case 
of  
diplodocoids. This is where the extreme ventriflection we see in Diplodocus and 
 
Apatosaurus for me makes sense: in an upright position in which the neck was  
nearly vertical, foraging in a downward/ forward range of motion would ensure 
an  effective feeding envelope in this situation. Call it the "cherry-picker"  
feeding mode. Seen in the context of their great spatial/ temporal range, both 
 feeding scenarios could have validity in explaning why sauropods were as  
successful as they were. Behavioral flexibilty probably had a lot to do with 
the 
 radiation and evolutionary success of the earlier prosauropods, and their 
bigger  and later relatives took it to even further specializations. 

Mark  Hallett 

MARK HALLETT PALEOART
4742 Liberty Rd. South, Ste.  175
Salem, OR 97302-5037 USA
ph: 503.831.1164/cell 503.999.8179
fax:  503.831.1544
email: marksabercat@aol.com
www.hallettpaleoart.com