Are you thinking predation in packs, or of small tick grooming critters hitching a lift like the lizards that groom seals on Galapagos? If the latter it makes me wonder whether sauropods could shiver.
ie, if something grabbed them by the neck*, could the sauropods move their necks side-to-side/up-and-down fast enough to dislodge/hurl away the grabbing thing?
thanks.
* = no, not a large therapod....say a person, or a small maniraptor.
_________________________________________________________________ http://liveearth.msn.com