Mangelia phrixae
Mangeliidae
Marginella vadosa
Marginellidae
Megalonyx jeffersoni
Megalonychidae
Megaselachus megalodon
Otodontidae
Megokkos macrospinus
Macropipidae
Mennerotodus mackayi
Odontaspididae
Menoceras arikarense
Rhinocerotidae
Merycoidodon culbertsoni
Merycoidodontidae
Mosasaurus hoffmani
Mosasauridae
Mosasaurus maximus
Mosasauridae
Mulinia congesta
Mactridae
Mulinia lateralis
Mactridae
Myliobatis aquila
Myliobatidae
Myliobatis californicus
Myliobatidae
Mylohyus nasutus
Tayassuidae
Negaprion brevirostris
Carcharhinidae
Neoglyphioceras subcirculare
Neoglyphioceratidae
Odocoileus virginianus
Cervidae
Odontaspis macrota
Odontaspidae