Definition of "heterodontism"

Now that all mammals are led back to a distant diphyodont stem, it is also true that the further we go back both in palingenesis and embryogenesis, the more widespread heterodontism is—all modern homodontism proving to be secondary.

1894, “Address by Henry Fairfield Osborn”, in Proceedings of the American Association for the Advancement of Science‎, volume 42, page 197