In what era did modern man first appear?

What is a cordon and where is it found

Cell specialization occurs by the process ofa. reproductionb. differentiationc. maturationd. growth

The table shows dates and appearance of index fossils. which rock layers can be dated most precisely? a) a layer containing both a fossil 4 and a fossil 3 b) a layer containing both a fossil 2 and a fossil 3 c) a layer containing both a fossil 1 and a fossil 4 d) a layer containing both a fossil 1 and a fossil 2