His is the chronicle of evolution over millions of years of geologic time engraved in the order which fossils appear in rock strata.

Fossil Record

Explanation:

    The fossil record is evidence that beings existed for many millions of years on the planet, the fossil record ranges from small amber insects, as in the figure below, to bones of large dinosaurs.

    Although not showing a complete view of the evolutionary process, the fossil record provides information on the minimum age of taxa, where time and intensity of differentiation is important in reconstructing the scenario of animal evolution.

a tetrad is the foursome during meiosis made by two homologous chromosomes that have each already replicated into a pair of sister chromatids.