It also shows up in Genesis 1 but to be fair, almost nobody understands Genesis 1 and to your point, Genesis 1 is covering the same scenario as Genesis 9: pole flip cataclysm that caused a global flood event. The 7 day story is meant to tell us what the aftermath of the pole flip looked like to the few survivors who made it through these evolutionary bottlenecks that explain punctuated equilibrium and stratigraphic homogeneity.