| Epoch of 50 million years ago | 29 |
| Epoch 50 million years ago | 26 |
| Certain geological epoch | 24 |
| A Tertiary Period epoch | 23 |
| Inits. in the classifieds | 25 |
| Classified letters, perhaps | 27 |
| Unbiased hirer, in ads | 22 |
| Unbiased hirer, briefly | 23 |
| No-bias-in-hiring abbr. | 23 |
| Letters in a help wanted ad | 27 |
| Initials in the want ads | 24 |
| Fair hirer's abbr. | 22 |
| Ancestor of the modern horse | 28 |
| Prehistoric stone tool | 22 |
| One billion years, in geology | 29 |
| Centuries and centuries | 23 |
| Long time, geologically | 23 |
| Long geological stretch | 23 |
| A billion years, in astronomy | 29 |
| Span of epoch proportions? | 26 |
| Mind-boggling time span | 23 |
| Geologic time division | 22 |
| Extremely long unit of time | 27 |
| Waiting period, seemingly | 25 |
| Long geologic time division | 27 |
| It's longer than an era | 27 |
| Indefinable time period | 23 |
| DMV wait time, seemingly | 24 |
| Division of geological time | 27 |
| Division of geologic time | 25 |
| Astronomical time period | 24 |
| Astronomer's time period | 28 |
| A bazillion jillion years | 25 |
| Years and years on end | 22 |
| Unimaginably long time | 22 |
| Unfathomably long time | 22 |
| Seemingly endless time | 22 |
| Phanerozoic, for instance | 25 |
| Period too long to measure | 26 |
| Long, long, long time period | 28 |
| It's split into eras | 24 |
| It may seem like an eternity | 28 |
| Forever and a day, seemingly | 28 |
| Extremely long time period | 26 |
| Billion-year time period | 24 |
| Astronomically long time | 24 |
| A gazillion years, seemingly | 28 |
| A billion years, in geology | 27 |
| What a waiting time may seem | 28 |
| Very long Supergrass song? | 26 |
| Unimaginable time period | 24 |
| Unbelievably long time | 22 |
| Two or more geological eras | 27 |
| Two or more eras, in geology | 28 |
| Twenty bajillion years | 22 |
| Time on hold, seemingly | 23 |
| Thousands of generations | 24 |
| This is going to take a while | 29 |
| Super-freaking-long time | 24 |
| Span longer than an era | 23 |
| Relative of a saeculum | 22 |
| Really long geological time | 27 |
| Phanerozoic, currently | 22 |
| Phanerozoic or Archean, e.g. | 28 |
| Period from B.C. to TV | 22 |
| One hundred million decades | 27 |
| One billion years to Hubble | 28 |
| Nearly infinite perioD | 22 |
| Myriad coon's ages | 22 |
| Millennium upon millennium | 26 |
| Many periods are in it | 22 |
| Long, long time period | 22 |
| Long, indefinite period | 23 |
| Long stretch of history | 23 |
| Long historical episode | 23 |
| Largest geological division | 27 |
| Large timeline segment | 22 |
| L-o-n-g stretch of time | 23 |
| Its make-up is many years | 25 |
| It's a real stretch | 23 |
| It's a big stretch | 22 |
| It seemingly never ends | 23 |
| It might be divided into eras | 29 |
| It keeps going and going ... | 28 |
| It is a long, long, long time | 29 |
| Interminably long time | 22 |
| Inordinately long time | 22 |
| Indefinitely long time | 22 |
| Incomprehensible time span | 26 |
| Incalculably long time | 22 |
| Half a million bimillennia | 26 |
| Hadean or Archean, e.g. | 23 |
| Great geological time span | 26 |
| Geologist's time period | 27 |
| Geologist's measure | 23 |
| Geologic-time measurement | 25 |
| Geologic division of time | 25 |
| Extremely long stretch | 22 |
| Cosmological unit of time | 25 |
| Big, big stretch of time | 24 |