Ah stu, surprised at you. I thought you were a fully informed evolutionist.b you should know that humans only(supposedly) came from one line of apes.          Organisms in fossil layers ? There is a general order as might be expected from 1 not living in the same areas , and 2 some creatures could get further and higher as the flood prevails. However, I think that if you were to look , there are instances of organisms washed and buried together.   If you want to know how speciation works try Darwin . Pity he speculated beyond the bounds of speciation within the limits of each organism. Plate tectonics , would that be slow as now , or rapid plate movements as perhaps occurred at the flood.      And the last ones real easy.... , the snail ,it evolved into a mudcatter who challenged you all to show him some evolution lol !