[Leo Shaw (OP)]

In an illustration I saw on a science program it appeared dark matter was concentrated around galaxies.  Is it possible that dark matter is actually only a myth caused by a special unknown type of gravity created by super massive black holes that causes the speeds of stars being equal at all places in the galaxies? 

[imatfaal]

It's very unlikely.  We still are not sure what dark matter is, but we try to look for the simplest explanations.  Changing the law of gravity, or introducing a new form of gravity is a very complicated and difficult solution.  The solution we currently favour is that the law's are the same but there is some stuff out there we cannot see and which, because we are not including it, screws up our sums.  But it is still up for grabs. 

[PhysBang]

The short answer is that there are too many things that dark matter has to do for it to be black holes. It has to change the behaviour of things in galaxies and in the early universe in such special ways that it cannot be localized to point sources like black holes.