It spans the time between 55.8 ± 0.2 Ma and 48.6 ± 0.2 Ma (million years ago). The stage is named after Ypres, Belgium. The famous Messel shales in Germany are from this age. Primates had appeared by 55 Ma, although the molecular clock and new paleontological finds state that they may have existed as early as the Late Cretaceous, 90 Ma.
|Paleocene epoch|| ||Oligocene epoch|
| Danian | Selandian|
| Ypresian | Lutetian|
Bartonian | Priabonian
|Rupelian | Chattian|