Mammals are plentiful in the Hell Creek Formation. Groups represented include multituberculates, metatherians, and eutherians. The multituberculates represented include "Paracimexomys", the cimolomyids "Paressonodon", "Meniscoessus", "Essonodon", "Cimolomys", "Cimolodon", and "Cimexomys"; and the neoplagiaulacids "Mesodma", and "Neoplagiaulax". The alphadontids "Alphadon", "Protalphodon", and "Turgidodon", pediomyids "Pediomys", "Protolambda", and "Leptalestes", the stagodontid "Didelphodon", the deltatheridiid "Nanocuris", the herpetotheriid "Nortedelphys", and the glasbiid "Glasbius" all represent metatherians of the Hell Creek Formation. A few eutherians are known, being represented by "Alostera", "Protungulatum", the cimolestids "Cimolestes" and "Batodon", the gypsonictopsid "Gypsonictops", and the possible nyctitheriid "Paranyctoides".