Geological Time Scale Chart. 700am-900 pm- Simple soft-bodied organisms like worms Little past 900pm - Complex organisms evolve in oceans Little past 1000pm - Reptiles and insects first appear Just before 1100pm - Dinosaurs arrive. The primary objective of the International Commission on Stratigraphy ICS is to precisely define global units systems series and stages of the International Chronostratigraphic Chart that in turn are the basis for the units periods epochs and age of the International Geologic Time Scale.
The time scale also shows the onset of major evolutionary and tectonic events affecting the North American continent and the Northern Cordillera SCAK south-central Alaska. Calling this span from roughly 66 Myr to 18 Myr the Tertiary Period is fairly common in geologic literature. GSA Geologic Time Scale.
Based on all the available evidences.
Geologic time scale showing the geologic eons eras periods epochs and associated dates in millions of years ago MYA. We are currenty building this geologic site and adjusting times and events listed on this geological time scale. The history of Earth has been divided into three eons. It combines a numerical scale that uses as a unit a million years chronometric scale and a scale in relative time units chronostratigraphic scale.