I've got to wonder how realistic this pose is.
Even if it could rear up and balance like that, the energy expenditure vs calorific gain seems like a losing proposition. You're talking about raising the center of gravity of it's 40-ton body mass by 10-20 feet just to grab a very small mouthful of low calorific leaves.
I'd guess the reason the sauropods had an extra long neck was rather so they could AVOID moving as much as possible - stand in one place and just swivel neck around to graze a large area.
How can an animal even have a neck that long? Was it clear from the fossils that it is this long because I am skeptical.
No, there's no way to tell—the paleontologists probably just took a bunch of bones from the site and threw them together in a way that looked cool. /s
He's got some neck!
this dinosaur has a soar throat