Rav Shmuel Halevi Wosner was asked (Shevet HaLevi 10:114:1) about an animal eaten in America that seems to be from the Buffalo family and clearly has the required Simanei Kashrus but it is unclear whether it qualifies as a beheima or chaya and has no Mesora. May you eat it?This question revolves around a Shach and Pri Megadim. There are differences in halacha with regard to eating the fat of an animal, whether it is a Chaya or Beheima. The Shach says that when there is a question whether an animal is a beheima or Chaya we should not rely on the Simanim without a mesora.
The Pri Megadim holds that even according to the Shach the chumra of mesora only applies to the question of whether you treat it like a chaya or beheima but in any event you can be assur the fat like a beheima and eat it without any mesora since the simanei kashrus are very clear. Only by birds do we require mesora and not rely on simanim.
However the Chazon Ish says that the Shach is to be taken literally and one may not eat any animal even if it clearly qualifies as kosher without a mesora. He bases this on Chochmas Adam and says that this was the minhag in Lithuania.
Rav Vosner says that adding all this up, in America there is no problem to eat this new kind of Buffalo since a) the minhag of mesora was only in Lithuania, b) the Pri Megadim holds the Shach didn’t require a mesora only for birds, c) this new Buffalo is close to the Buffalo family that has a mesora.