Hi Crystal, from the pictures it is obvious to me that the trees are dead.  They have no leaves that are present now.  Maybe a different view with the camera would show you more live leaves but it looks to me that the trees are indeed dead.  
Here is what happens to trees that grow close to each other.  They form root grafts when the roots grow over each other.  They fuse together in a graft so when a pathogen invades the roots of one tree, the pathogen is translocated to the other trees that they are attached to.  I think this is probably what has happened. 
As for the dark area under the bark, I have seen this before but I can't find the reference for it right now.  It is an indication that the tree is dead and the bark underneath is totally dead - hence, black.  
Here is what I would do:  I would ask around if someone knows an Arborist, preferably a Certified Arborist, who can come by and advise you on what your options are right now.  You will have to get someone to take the dead trees down anyway before very long. You don't want to let the dead trees stand there because they are a hazard to you and your property.  The fence is an easy target for the trees to fall upon.  Some trees will stay there for a long time and nothing falls from them and other trees will drop limbs after about a year and a half.  Dead trees are deadly!!!
I hope this helps you.  Don