Cetiophidae

This is going off of the idea I introduced a while back about the fully-aquatic spinosaurids. Let's say, for the sake of hypothesis, that Spinosaurus in all of its bizarre-ness survived to reach the oceans. Once in the open, it'd have the opportunity to fill several different niches and possibly even survive to the present. Sure, it hasn't happened yet, but it's still a bit of fun to guess at what they'd do with their unlimited options.
I call its family Cetiophidae, or the 'whale serpents'.

Rendered in Photoshop on a graphic tablet.