I was made aware of this not long ago - it kind of looks creepy, but it gave me an idea:
Did Spinosaurus walk like a pangolin?
That is, with it's hands low to the ground but not touching the ground - so no knuckle walking - and maintaining balance as a biped...
This pangolin seems to maintain balance on its hind legs even though, on cursory glance, its centre of mass seems too far forward for that.
Spinosaurus is supposed to have had a dense femur, so maybe its centre of gravity was farther back than you'd think from overall proportions. Maybe the sail helped tip the scale back?
...or maybe it was a giant ant-eater? Those giant claws look particularly suited to breaking open termite mounds?
Who knows. This is me being silly, but thought it was hilarious enough to share...