Show your work.
My rough calculation based on numbers from Wikipedia is that with Indohyus around ~50mya and Basilosaurus ~40mya, there were 10my between them. If the generation time was ~5 years, that’s 2m generations - so for your 10^11 to be correct, the average global population of cetaceans throughout that time would have to be less than 50,000.
Since the current population of a single species of whale (orca) is about that size, your estimate is ludicrously low.
Ok. I’ve pondered the difference between a ludicrous overestimate and a ludicrous underestimate, and I see no problem whatsoever.
So show your work.