I’m wondering how one could know that no cetaceans were killed in the flood. I have never heard anyone say that the fossils are a complete record of all individuals who ever lived. Some could have died without being buried, floated and rotted, etc. The hundreds of species of reptiles mentioned as never living after their layers of fossils aren’t evidence that the flood narrative in inaccurate. The ark carried air-breathing land animals only. And even then some could have survived the flood and later gone extinct.