The classification presented in this paper follows Simpson (1945) and Olsen (1972) for the American mastodont, and Simpson (1945) and Maglio (1973) for the mammoth.
The proboscideans that lived in Michigan during the Pleistocene are the American mastodont (Mammut americanum) and mammoth (Mammuthus spp.).
Here, I document a supernumerary tooth in the American mastodont (Mammut americanum) based on USNM (National Museum of Natural History, Smithsonian Institution, Washington, D.C.) 2225 from Pleistocene deposits near Afton, Oklahoma (see Hay, 1924 for locality information).
American mastodont from the Sandia Mountains, New Mexico.