I wanted to add these two beasties. Hopefully I can convince a DM to at least let my character have the dog-croc as a familiar for my Genasi wizard, but it'd be stellar if I could convince one to let me have the kaprosuchus as a mount for my lizardman barbarian. BTW, if you're playing
Tomb of Annihilation, both of these would be good encounters to add.
The kaprosuchus is for pretty much any version of the game since I couldn't find 3.5/Pathfinder stats for giant crocodile. The above dogcroc is for 5e, and the one below is for 3.5 and pathfinder.