Paleogene Period
Geologic Age
66.0–23.03 million years ago
Eon / Era / Epoch
What happened during this time?
Geophysical
Climate cools during the middle to late Paleogene
Carbon dioxide levels begin around 900 ppm, increase to 1,000 ppm at the PETM, and then start to drop to 500 ppm by the end of the period
Oxygen levels start at 23% and hover around 21.5%, close to modern levels
Continents in similar geography to today
Biological
Flora
The Paleogene is a time of recovery from the Cretaceous extinction
Many extant modern plants arose during this time.
As the Earth cools and dries, many wet, tropical plants are replaced by coll-adapted, dry-adapted plants
Conifers, retreat to mountainous areas due to angiosperm competition
Fauna
Animals recover from the Cretaceous extinction
This is the rise of mammals in which they begin to fill the niches left empty by dinosaur extinction
Additional Resources
Fossil forest under Antarctic ice (Phys.org, Mar 2021)