Supertide wiped out the Dinosaurs.
The comet cameth, and it brings with it an immense gravitation pull.
It pulled Mars oceans into space, and it caused an unbelievable tide on Earth.
Perhaps a thousand feet high.
This tide inundated entire continents, and when it drained out, the tremendous flow of water carved out all the canyons and fiords on earth.
As the water waned, the bodies of the drowned dino's washed up together, into piles, and its the reason so many fossils are found all bunched up.
As the tide grew higher, the low tides began to drain the ocean basins. and as the runoff poured into the now empty basins, it carved out river canyons, that are still visible today, but under the sea,