Cryptocrocagator
If this isn't a hoax, then it could very well be a new species. It has no flukes, it has hair, and a skull like a dolphin. At least we have a set of good clear photos, enough so that an anatomical expert can definitely rule out the only "conventional" thing I think it might be: a highly decomposed elephant seal or walrus. The photographer got good shots of the skull and teeth, and that should clinch the ID if it is indeed a known animal.