| Hyposaurus(noun, extinction, paleocene, genus) |
| Hypsamasia(noun, eocene, extinction, genus) |
| Idrissia(noun, eocene, extinction, genus) |
| Isocrania(noun, extinction, paleocene, genus) |
| Jiangxia(noun, extinction, paleocene, genus) |
| Kankatodus(noun, extinction, paleocene, genus) |
| Kimbetohia(noun, extinction, paleocene, genus) |
| Kingena(noun, extinction, paleocene, genus) |
| Krauseia(noun, extinction, paleocene, genus) |
| Lambdopsalis(noun, extinction, paleocene, genus) |
| Lammidhania(noun, eocene, extinction, genus) |
| Leptictidium(noun, fauna, extinction, priabonian) |
| Leptoreodon(noun, fauna, extinction, priabonian) |
| Leptotragulus(noun, fauna, extinction, priabonian) |
| Linthia(noun, eocene, extinction, genus) |
| Liotomus(noun, extinction, paleocene, genus) |
| Lithornis(noun, fauna, extinction, bartonian) |
| Lithornithidae(noun, fauna, extinction, bartonian) |
| Machaeroides(noun, eocene, extinction, genus) |
| Madtsoia(noun, eocene, extinction, genus) |