Did the megalodon live before dinosaurs?

C. megalodon was definitely an apex predator for more than 20 million years.

Amazingly, this doen not mean megalodons could not have been preyed by other very large predators.

During the Miocene, very large predators, like Livyatan melvillei, shared the same waters, and searching for the same preys. Encounters were inevitable.

This predatory odontoceti cetacian could reached the same size of extant sperm whales, or even larger. Confirmed lenght of more than 17 metres is accepted today by paleontologists, but VERY FEW fossils of this apex predatory whale were found. Larger individuals are a probabilistic certitude.

Moreover, Livyatan melvillei had not only teeth in BOTH upper and lower jaws - unlike sperm whales - but they had much larger teeth than megalodon (36 cm lenght confirmed).

(As a matter of fact, Livyatan melvillei had the largest teeth EVER found in a carnivorous predator, incuding tyranosaurus, pliOSaurs, mosasaurs and...

...megalodons!)

And Livyatan melvillei most probably hunted in packs, and were formidable predators.

About the maximum size of C. megalodon, the present consensus among paleontologists is that megalodons probabiy had an average lenght of about 16 metres, and large specimens could be not much more than 20.3 metres, according to the fossil teeth and vertebra centra available at the time of this consensus.

In the meantime, a considerable larger fossil teeth was found, with 193.67 millimetres (7.625 inches) in total height (previously, the maximum fossil teeth height was 168 millimetres (6.6 inches).

The truth is nobody knows for sure how large a megadolon could be.