What breed is my cat?

Hello everyone,

Ever since we adopted our cat Nathaniel from the animal shelter my wife and I have've wondered what breed he might be. He's a relatively large cat (pictures below), who weighs about 15-16ibs, with silky long-to-medium black hair which is amazing to touch, a mane and fluffy tail. He's very muscular and has exceptional jumping abilities. He also appears to have relatively short front legs, but longer back legs. He's quite talkative and makes little chirrup sounds. He's also rather dog-like and doesn't like to be left alone for too long. He's highly intelligent (from what we can gather), and affectionate on his own terms: i.e. he doesn't like being held too long and is usually sceptical of strangers until he gets to know them. A friend of ours thought he looked like a Siberian cat.

Any thoughts?

He very well might be a Maine Coon Cat! I'm saying this based on how fluffy he is, and  the big "M"-like shape on his forehead. They are very nice cats, I have one myself and he is a gentle giant.

Hopefully this helps a little bit, however I could also be wrong! 

One of my cats looks exactly like that! Not even kidding, right on down to the reddish highlights in the mane. It's hard to tell from the pictures, but does he have reddish highlights on his belly too? Ours does. Our cat isn't a Maine Coon, hes just a long-haired domestic, which is what I'm guessing your cat is.