Noun: Tertiary period
- The geological period from approximately 65 million to 2.6 million years ago, marked by the development of mammals
"Many modern mammal groups evolved during the Tertiary period";
- Tertiary
Derived forms: Tertiary periods
Type of: geological period, period
Part of: Age of Mammals, Cainozoic, Cenozoic, Cenozoic era
Encyclopedia: Tertiary period