What kind of animals are my trolls?

Edit: I've written an answer of my own now, and I'd appreciate it if any of you informed on the subject of evolution could review it, then inform me of its plausibility, via the comments (Of the answer).

---

There are four other questions in my series of such, which I am asking to deal with problems I have encountered while working on my current worldbuilding project, which seeks to portray the biology of fantasy creatures in a viable way. The last was How can I explain the evolution of my giants?, and the previous three are linked there.

Now, I am asking about another of my fantasy beasts. The troll is featured in Scandinavian mythology as a burly, large-nosed beast that turns to dust when exposed to sunlight. Trolls are often represented in artwork as heavy-set, giant creatures, but the trolls in my project are slightly different.

My trolls are more lanky, semi-aquatic, with elongated snouts and long, goblin-like noses. Here is an illustration of a similar style of troll:

Image source: Spiderwick Chronicles Wiki

While not entirely the same, the basic anatomy is very similar. But what I can't figure out is: What kind of animal is this troll?

At first, I thought of a derived crocodilomorph with strong forearms, but I later discarded that theory because it has hair and a long, human-like nose, features which reptiles wouldn't have any reason to evolve.

My next idea was that it was amphibian. The hair could in fact be external projections of the skin - there is a frog which has such a trait. But that still doesn't explain the nose.

The only other possibility I can see is that it's a mammal. But what kind of mammal? It has quite a primate-like form, but a reptilian head and skin. However, I think this is the most likely of the three ideas I've put forward, but there are some things that need to be explained should you try to testify this statement.

So, to you, is this beast crocodilian, amphibian, primate or something else? I am open to any theory as long as it is backed-up with information and explains how the traits the troll has but its relatives don't evolve.

Edit: I've thought about this question more, and I can think of some reasons why certain traits would evolve. The hairlessness reduces drag underwater, strong forearms are good for swimming, and an elongated snout is good for snaring fish. Also, I noticed something in the picture I hadn't seen before. In the bottom left, it says:

"These long arms are perfect for reaching over a bridge and grabbing passers-by"

This instantly made me think of a crocodile's predation method, where they hide under the water and grab the snouts of zebra or wildebeest. This also supports my original crocodilomorph theory. If this inspires any ideas, or gives you clues as to why other traits would be useful for a water-to-ground ambush predator, answers would be greatly appreciated.