Evolution

Evolution spiral

Usually animal enclopedies like ours count time from Phanerozoic, which starts about 500 million years ago and divides in three parts, Paleozoic, Mesozoic and Cenozoic.
Paleozoic divides in six smaller periods and first form of life is created in Cambrian which is first of six periods. Those were small fossils and celled organisms. Ordovician, formation of first multicellular organisms. Silurian period is specific for first small bugs and ancient critters. Devonian and Carboniferous periods are tipical for evolution of citters into small animals, and form of primitive mammals.
Next big period is Mesozoic which is period of dinosaurs. Sepparated in three smaller periods, Triassic(small ancient dinosaurs), Jurassic(most known by people, top of dinosaur evolution) and Cretaceous(end of period is extinction of dinosaurs).

Development of mammalian
About sixty million years ago large meteor hit Earth and raised dust in atmosphere. Dinosaurs couldn't live without Sun energy, and after few months they extinct. That is the end of one great period Mesozoic and beginning of Cenozoic or period of mammalian. It took about 50 million years to human ancestors start walking on Earth. That was the beginning of human race.