Another simple question (I think)

[rking@mailhost.flir.COM (A really swell guy who plays go!)]

I just returned from Alberta.  Its hard to get back to real life.  :-(

At Dinosaur Park, they used abbreviations I thought I understood, but now
have doubts about the specifics.  

In their classifications, they list the genus and species usually.  Its
the exceptions that threw me.  

One listing was:   Pachycephalasaurus n. gen., n. sp.

another:  Tyranasaurid n. sp.

another  Somethingasaurid sp.

Forget my assumptions, what does it all mean?

Thanks,
Randy