Let me clarify and amend my previous post. First of all I checked zip code 07054 (Parsippany) instead of 07504 (Paterson)-a little typing dyslexia there.
I just checked the correct zip code in the MLS. What I said holds true at least about the house prices being low (and below assessed value) because of short sales/as is sales/ fixer-upper homes/ fire damaged homes etc in the lower price brackets almost 100% of the time.
However there are 230 homes listed under $300k and it appears that almost all of those are also listed way under assessed value. And from my brief checking even most of the houses listed OVER 300K are listed below their assesed values as well.
I again suggest that you contact a local Realtor and ask what's happening, and/or contact the tax assessors office, to find out why the assesed values is so high as opposed to list/sales prices.