First appearances of biota during the Chattian Age, the geologic time between 28.1 and 23 million million years ago, during the Oligocene Epoch of the Paleogene Period in the Cenozoic Era.
This category has the following 3 subcategories, out of 3 total.
The following 23 pages are in this category, out of 23 total. This list may not reflect recent changes.