"Please, someone, explain how on earth a long neck is of benefit to any
grazer/low browser?"
Scott Hartman
For very massive browsers such as the sauropods, a long neck makes sense to
me in terms of energetics. A long neck, which allows the animal to vacuum
up biomass over a large area without moving its entire body, would have
tended to increase the time spent feeding and decrease the time spent moving
from one feeding location to another. Moving from one feeding location to
another is more energetically expensive than standing in one place and
eating. Not only does it take a lot of energy to move 50 or 100 tons, but
it's likely the animal wasn't actively browsing while moving to a new
location.