Thanks a lot, t1ck! Much appreciated.

I am not sure about the final pose. I may open the mouth up a little wider, maybe lifting the upper part of the mouth. What do you think?

I have been working from a ton of hippo photos and, as I think you mentioned in another post, it can be difficult to define the animal when you realise just how different each animal looks.

I eventually plan (hope) to rig the head so that I can open and close it, but that is probably a long way off...