Mhh... crossopterygian got outta the water and was transformed due to the radioactivity that was resident at primal-earth (his genes in fact). That was goin on for some time so shore- and land-living reptiles evolved.
Reptiles rul0red for some time. Then mammals took over. Pro'lly meteor impact or heavy volcanic activity.
At some time ape-like animals divided into some branch that developed into humans.
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