| EOCENE | Second epoch of the Tertiary period, between 56 and 34 million years ago (6) |
| OLIGOCENE | Of the Tertiary period between 34 and 23 million years ago (9) |
| PLIOCENE | Epoch of Tertiary period between Miocene and Pleistocene (8) |
| AOLER | One of about 34 million surfers |
| EOCINE | Second epoch of the Tertiary period |
| MIOCENE | Fourth epoch of the Tertiary period, occurring between the Oligocene and the Pliocene (7) |
| OSSIAN | Legendary Irish hero and bard of the 3rd Century (6) |
| PLEIOCENE | An epoch of the Tertiary period, beginning over 5.3 million years ago (9) |
| BEYOND | With more E.T. heads around, close encounters are still out of reach - unless of the 3rd kind? (6) |
| EUCLID | Geometrician of the 3rd century BC (6) |
| HOLOCENE | In geology the second epoch of the Quaternary period (8) |
| NEOGENE | Later division of the Tertiary period of the Cenozoic era, subdivided into the Miocene and Pliocene epochs (7) |
| PALEEOCENE | Earliest epoch of the Tertiary period (10) |
| AMBER | Fossilised resin of extinct coniferous trees of the Tertiary period, commonly used as a gemstone (5) |
| BEAUTY | With 33-Down, where to go for the ends of 16-, 20-, 40-, 56- and 62-Across |
| NEOCENE | Division of the Tertiary period |
| SABRETOOTH | Extinct feline carnivore of the Tertiary period (10) |
| YOUCAN | With 42-Across, "I don't want that" ... or a hint to the starts of 17-, 26-, 56- and 66-Across |
| CECIL | Literary critic and Oxford don who was a grandson of the 3rd Marquess of Salisbury, the Victorian statesman who served as prime minister three times (5) |
| MANETHO | Egyptian priest of the 3rd century BC whose Greek Aegyptiaca (History of Egypt) originated the concept of pharaonic dynasties (7) |
