What is the tallest dinosaur?

The problems associated with estimating heights for dinosaurs are many fold.

For starters, we don't know at what angle dinosaurs held their neck. And we don't know how long potentially the longest necks actually were, because dirty great lumps of them are often missing. On top of that, connective tissue, cartillage and whatnot, doesn't fossilize well (or at all, in fact) but they would certainly have added a little something to the height.

For the former reasons, we measure all dinosaurs from floor to hip height. But being the tallest dinosaur doesn't necessarily make it the all round biggest. Some were tall but not especially long, others were insanely long but not particularly tall, and neither length nor height alone are reliable yardsticks for estimating mass.