Tertiary

The Tertiary period is one of the major divisions of the geologic timescale, from the end of the Mesozoic period about 64 million years ago to the start of the Quaternary period about 1.6 million years ago. The Tertiary includes five geologic epochs -- the Paleocene, Eocene, Oligocene, Miocene and Pliocene. The Tertiary is sometimes divided into two sub-periods called the Paleogene? and Neogene.

The term Tertiary dates to the 19th Century and relates to the fact that it was the third of four geologic periods identified by European geologists. It covers the time span between the demise of the Dinosaurs and a time in the recent past when periodic glaciations started and when recognizable human ancestors had evolved.

The sixty million years of the Tertiary represents the time during which most modern families of birds, mammals and flowering plants evolved . Marine invertebrates and marine vertebrates other than the marine mammals experienced only modest evolution.

Continental drift was modest. India broke loose from Africa and attached itself to Asia. South America attached itself to North America toward the end of the Tertiary. Antarctica -- which was already separate -- drifted to its current position over the South Pole. Climates during the Tertiary slowly cooled starting off tropical to moderate worldwide in the Paleocene and ending up with extensive glaciations at the end of the period.