Could this be a possible use of Spinosaurus' sail?
Black Herons, while fishing, will tuck their head down, spread their wings around their body, and create a sun shade of sorts. The behavior is known as canopy feeding.
Possible advantages to canopy feeding are:
Small fish looking for places to hide are attracted to the shade created by the Heron’s wings.
Could also give the bird a better look at its prey.
The Heron might also be camouflaging itself so that from below all the fish see is a single dark mass—until they’re being tossed down the bird’s gullet.
Could Spinos have done the same? Just thought of this & wanted to share this with y'all to see what y'all think.
Black Heron image & info from: https://www.audubon.org/news/watch-black-heron-fool-fish-turning-umbrella#:~:text=But%20while%20fishing%2C%20the%20bird,on%20a%20trip%20to%20Gambia.
Spino's skeleton image from: https://en.m.wikipedia.org/wiki/Spinosaurus