| Lithornis(noun, fauna, extinction, bartonian) |
| Lithornithidae(noun, fauna, extinction, bartonian) |
| Machaeroides(noun, eocene, extinction, genus) |
| Madtsoia(noun, eocene, extinction, genus) |
| Megacerops(noun, fauna, extinction, priabonian) |
| Mesodma(noun, extinction, paleocene, genus) |
| Mesonyx(noun, eocene, extinction, genus) |
| Metanephrocerus(noun, fauna, extinction, priabonian) |
| Metarhinus(noun, eocene, extinction, genus) |
| Metatelmatherium(noun, fauna, extinction, priabonian) |
| Metopaster(noun, eocene, extinction, genus) |
| Microcosmodon(noun, extinction, paleocene, genus) |
| Mimetodon(noun, extinction, paleocene, genus) |
| Miohippus(noun, fauna, extinction, oligocene) |
| Multituberculata(noun, fauna, extinction, oligocene) |
| Neoliotomus(noun, extinction, paleocene, genus) |
| Neoplagiaulax(noun, extinction, paleocene, genus) |
| Omomyidae(noun, fauna, extinction, oligocene) |
| Orohippus(noun, eocene, extinction, genus) |
| Oxyaena(noun, eocene, extinction, genus) |