If Giant Meteor Killed Off the Dinosaurs Then Why are All the Fossils Found Within Sedimentary Layers Laid Down in Water?

Why would a huge meteor impact have caused the extinction of the dinosaurs while not the extinction of the other kinds of animals, and why are the dinosaur fossils found within sedimentary layers which were laid down in water if the fire and debris from a meteor impact killed them? See the dynamics of the flood which entombed them at Page titled Natural Selection by Noah’s Flood.