In turn, the extinction of the dinosaurs and several other animal groups 65.5 million years ago defines the beginning of the Cenozoic era. We are including several pages with geologic time scale data ...

Prehistoric time line, geologic time scale ... modern humans emerged in the Cenozoic era. The planet has seen an incredible series of changes—discover them for yourself.

I like to use a meter stick and be very intentional with my spacing to model time as a scale. I also avoid using the far right ... of the Earth that is characteristic of a particular span of geologic ...