You may well be right. But I'll counter with the relevant paragraph
from Heinrich et al. (2011):
"Several fully articulated feet of Brachiosaurus, Janenschia
and Tornieria, buried in an upright natural
position, indicate that huge sauropods also visited the
lagoon and, at least occasionally, got stuck in the
mud. Such articulated parts of skeletons are rare and
accumulations of disarticulated bones of sauropods
prevail. Interestingly, all these assemblages are dominated
by bones of adult individuals. Therefore, some
palaeontologists believe that body weight was an important
selective factor for the survival of sauropods.
Because of their lower weight, juvenile sauropods less
frequently mired than adults who often passed the
point-of-no-return due to their heavier body weight."