Just got laid off, what to say/put on my resume/interview?

[AngelFire132]

So I just got laid off from my first job about 4 days ago...it was a part time job that I had for 10 months. Unfortunately, I have put this job on my resume, as the duties I performed were relevant to future jobs I am seeking.

The clinic I was working at came under new management two months ago, and this new supervisor I had wasn't...good at what he did. He never made his expectations clear to me, rarely told me what I needed to do (he gave me a short list of my duties, which I followed religiously while at work, and I always finished my work rather quickly) other than my normal duties, and just didn't seem like he knew what he was doing. When he became director at our clinic, we also got a new coworker who was rather incompetent and seemed to have a lot of trouble doing her job.

I was laid off last Friday, and my bosses cited the reasons as such:

1) He felt like he couldn't depend on me (even though he never made it clear what time I was supposed to come in...I was part time and my hours used to vary).
2) He felt like I didn't do enough, even though I did all my duties I was trained to do under the original management. He also rarely gave me additional assignments.
3) He complained that I always "seemed like I was in a hurry to leave", though he knew I had to rush to catch the bus after work. There was also a period that I was undergoing summer classes and had to leave earlier than expected, but my supervisor knew this several weeks before my class started, and was fine with it. There were also many times when I stayed longer than my shift, and before I left I would always talk to him and ask if there was anything else he needed done. I never left work until he was satisfied with everything I'd done that day.
4) Lastly, he said that he needed somebody with more medical reception experience, dealing with insurance/billing, etc, which I wasn't trained to do.

When I asked my supervisor why he didn't just give me a list of everything I could possibly do, his excuse was that he was too busy (when he really wasn't...his schedule was never full on patients and his office was close to my desk).

He also mentioned that he thought I was a great person, that everything I did, I did a really good job, and that I was great with patients. He then said I asked him about being a reference for future jobs, and he said that he would be honest and tell them what he liked about me, as well as what he didn't like.

I've written up my resume, but I didn't include my reasons for leaving (I'm hoping to discuss that during the interview). Though I'm sure the question will come up as to why I left...and when it does how should I answer it?

My second question is, would it be a good idea to list this supervisor as a reference? If not, would it be okay if I listed my previous supervisor as a reference instead?

Thanks in advance for any answers/advice