the way I see it turkey does have a mesora. My Father, Grand father and Great grand father were all God-fearing Jews and ate Turkey. I and most of those I know do in fact have a mesora allowing Turkey.
As to how my Great great great (insert as many as needed) Grandfather ate turkey without a mesora, well that is a very interesting historical question that doesn’t have much practical application.
So, in essence, once something has lasted long enough (subject to debate, but, just to pick a number, let’s say 100 years), then it has de facto mesorah status, even if, in fact, there may be no actual mesorah on the matter beyond then?
The Wolf