I know they were at least 10 years old, probably older. I found some images and discussion of this line of shoes from ~2007. Unfortunately I didn't check what the make of the shoe was before I threw them away. The Adizero Pro logo looks more familiar but the images that most look like my shoes I've found as "RC DC".
I asked for some advice in a running shoe forum and the suggestions don't really look like what I'm looking for, they all have thick heels that stick out. There are some track and field shoes that look like a similar profile, but they have the metal holes for spikes. Xero shoes also look kind of what I am looking for, but I don't really want barefoot shoes, just lightweight flats.