Don't forget the MD-80 and you can add 777's as well. Though we never acquired a 777, it was on the certificate and pilots were trained. When deals fell through for a 777, that's when they switched to 330's.

As James said, if you aren't flying a certain type, resources are not usually spent, both within the company and the FAA, to maintain the type. If they aren't maintained, they come out of the Ops Specs. It's all irrelevant anyway, PEX didn't acquire the Ryan certificate. Rumor has it the FAA closed the Ryan certificate in the last few weeks. Rather unfortunate, not many certificates had as many authorizations and types flown throughout the years.