Dog breed ID?

[treegod]

I have a one-year-old "mastiff", described to us as a Pyrenean mastiff, but by pictures it doesn't quite seem right. He does have the typical "six claws" of a mastiff, but I'm not sure if that's isolated to mastiff breeds or not. At least his mother did bear a resemblance to the Pyrenean mastiff.
Recently I saw pictures of a Carpathian mountain dog that showed a striking resemblence to them.
I'm leaving three pictures of him at different ages. In one he's playing with our bulldog x french bulldog.
Thanks in advance for any help (ID-ing dogs by photo is difficult, I know, but I just want to investigate possibilities).

For what it's worth, here are some relevant Wiki articles:
This is what we were told: http://en.wikipedia.org/wiki/Pyrenean_Mastiff
This is what we are suspecting (we're not aware of other breeds that look like this): http://en.wikipedia.org/wiki/Carpathian_Shepherd_Dog
Catalan Sheepdog (Gos d'Atura) has also been a guess - and by his facial hair I wouldn't be surprised he has some of this or something similar: http://en.wikipedia.org/wiki/Gos_d'atura

 

[Southern by choice]

It is very difficult to say.
How large is he? From the pics there is no way to determine weight or height.
Briards also have the extra dewclaws. They are a very hairy breed that looks similar to the Catalan, it is also a herding breed not a Livestock Guardian Breed.
The ears are saying something altogether different and the coat is questionable.

 

[bcnewe2]

He does look like he has briard ears. What other lgd breeds besides pyrs have the extra dew claw?

 

[BrownSheep]

I think a lot of large breed dogs posses extra few claws actually, but I may be wrong

 

[bcnewe2]

I've seen border collies born with them. Usually they clip them off as wee pups. They tear easy on working dogs.

 

[drdoolittle]

Is he the one in the first picture? Almost looks like he has some Belgian Sheepdog in him (Terveran (sp?))

 

[Southern by choice]

Maybe part Pyrenean Shepherd but not Pyrenean Mastiff.
The Pyrenean Shepherd Dog looks a little similar to a small briard.