Segregated vs age-mixed sauropod herds

[David Krentz <ddkrentz@charter.net>]

From what I've been reading, there seems to be a good amount of  
evidence for segregated sauropod herds, but not as much for mixed  
age.  If there were mixed age groups, would the youngsters have been  
cared for at birth until they were older as some accounts suggest?   
That seems silly to me, as the food requirements for sauropods would  
cause the herd to constantly keep moving, and all those little feet  
would surly slow the faster moving adults.  Or, would the lighter  
juveniles be able to keep up with the weightier adults?  I recall  
reading that there are sauropod trackways with juveniles in tow to  
support the mixed theory, but are there bone beds too?
 I suppose that there were many different strategies that were  
employed by the many sauropod species, just like the many kinds of  
child rearing/abandoning behavior in crocs and turtles.