Utter twaddle. There is a 100 year old principle called Cope's Law (only a Law, which scientifically means it isn't as firmly established as a Theory - but is nevertheless a good statement on how the real world works) that states that over evolutionary time related animals tend to increase in size.
In evolutionary terms this makes sense: bigger anumals usually have an advantage in survival and breeding and so have a reproductive advantage.
But "bouyancy sorting" says that fossils of the same shape, structure, density should sort out with the largest on the bottom of the fossil record, if it was constructed in one "Flood Event" - which thus falsified.
Bouyancy sorting is observable. What's more, it states that critters with the same level of tendancy to be bouyant will sort to the same level. This is observable with test objects in a lab. Cope's Law, on the other hand, is not observable and actually derives from theory based on theory.. And to the assumption that science has a clue what it's talking about with regard to said theory to the exclusion of all other possibility. For a theory that is yet unproven to produce laws based on assumption which you then inject here as a matter of dispute is begging the question. Where did you learn logic - or did you ever? Because what you just did is beg your argument to support your argument and that violates the first law of logic.