The offspring that can be described by the genotype is Gg while for the phenotype is green pod color
The cross between GG and gg give a heterozygous offspring that Gg offspring. The offspring are have a green pod color since the green pod color is dominant over yellow pod color and therefore the offspring have a green pod color. The cross is as the punnet square below.
You could use the fossil record to help explain the evolution of a species by watching how it aged, what it ate, how it breed and where it lived along with a million of other things. It could have lived in the 20 below freezing and then you find that same fossil in the warmest place in the world it shows that the species either adapted or possibly had an offspring that could handle the high temperatures.