Hi, I would not say that the lack of fossils in flood deposits proves there was no global flood. However, it is not consistent with YEC expectations unless they think that cetaceans rapids evolved post-flood which I have not seen in their literature. Likewise the lack of sea reptiles after flood deposits is inconsistent with what one would expect. The same shallow seas that preserved whales should also have preserved sea reptiles. There are many more pieces of evidence to consider that I did not have room to talk about here. For example, the teeth of sea reptiles are also found in Triassic/Jurassic/Cret deposits even apart from the rest of the bodies attesting to their presence but none are found in later rocks. No part of any whale is found in lower rocks. If both had been swimming around in pre-flood waters which would be the null hypothesis unless there was some reason to believe they weren’t (AiG thinks they were since they show them swimming together in the image) then the pattern of the fossil record does not support a global flood as the causative agent of the geological column.