Q. Can you wear shoes made of alligator, shark or ostrich skins on Yom Kippur?

A. Horav Shlomo Miller Shlit’a pointed to the Talmud (Shabbos 108:1) that teaches that for the purpose of making tefilin, even batim made from the skin of fish would have been permitted, if not for other ulterior reasons, since they are actually considered as leather. See similar opinion in Maadanei Danniel (614: p. 440).

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a