Claim: Paleogene is a geologic system that spans 48 million years.
Evidence: The Paleogene -LRB- -LSB- pronˈpæliːədʒiːn -RSB- or -LSB- ˈpeɪliːədʒiːn -RSB- also spelled Palaeogene or Palæogene ; informally Lower Tertiary -RRB- is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago -LRB- Mya -RRB- to the beginning of the Neogene Period Mya.