A Big Dinosaur

[Dark Lightning]

It's amazing that the thing can even hold its head up with that long skinny neck.

[Recusant]

Astute observation. 

Apparently there are differing opinions regarding the neck posture of sauropods. Some argue for a more horizontal posture, while others argue for an upright posture. There are a number of pages about it, and what I took from my explorations is that some of the big sauropods may have had an upright neck posture and likely many did not.

The two pages linked are only examples (it's a rabbit hole one can spend some time on) but there's a Wikipedia page on the topic that I think does a fair job of giving an overview.

I sort of assume that the artist consulted with the authors of the paper when he was creating his "artist's impression." If so it would seem they're firmly in the upright neck posture camp for this particular sauropod.