How was the environment of the megalodons?

Answer 1

This is a very difficult question to answer, for two main reasons:

a) C. megalodon lived for over 20,000,000 years, and a lot happened in earth's marine and climatic environements during such a long period of time.

b) Paleoclimatologists are still trying to understand the complexity of climate changes during the Cenozoic era which, in turn, directly affected the oceans currents, temperatures, salinity, etc.

C. megalodon appears in the fossil register in the Late Oligocene, when temperatures began to rise after the Early Oligocene abrupt temperature decline (the first time in the Tertiary era that Antarctica was covered by ice).

During Late Oligocene, Antarctica was linked to Australia AND to South America, but Panama Isthmus did not existed yet. This means a totally different oceanic current worldwide system from today's oceanic currents. The Pacific and Atlantic oceans were connected, and no ocean conveyor belt existed.

During the next period, the Miocene, temperatures became warmer, and Antarctica lost its ice cap.

In the Miocene, cetaceans reached its highest diversity, and it was a flourishing period for the megalodon, because of abundance of food and warm oceanic water.

But the megalodon at that time shared the top of the food chain with another formidable apex predator, the Livyatan melvillei, its «Nemesis».

This predatory odontoceti cetacian could reached the same size of extant sperm whales, or could be 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 today's sperm whales - but they had much larger teeth than megalodon (36 cm lenght, confirmed).

The Middle Miocene extinction reached its peak, and a wave of extinctions of marine life diminuished megalodon food supply. Neverthless, the megalodon thrived.

In the Late Miocene temperatures droped again, and Antarctica suffered a glaciation.

In colder waters, more cetaceans became extint, including the mighty Livyatan melvillei. However, C. megalodonsurvived without a significant decrease of population.

The next period, the Pliocene, arrived and temperatures kept dropping. Whale species became much larger, some reaching or exceeding the size of the extant blue whale.

C. megalodon, beeing a warm blooded shark, adapted the best he could to colder oceans, although he prefers warm waters. It changed its prey attack behavior to feed on larger whales, and became also larger and adopted a more brutal attack to the new preys.

The Drake Passage opened and Australia is no longer attached to Antarctica.

North and South Americas are now connected, and the Pacific/Atlantic connection is over, except through the difficult and cold Drake Passage. The Isthmus of Panama made the end of the final remnant of what was once essentially a circum-equatorial oceanic current, for tens of millions of years.

Megalodon populations from the Pacific loose contact with the Atlantic populations, which became reduced to relic populations over time.

The Pacific is much, much larger and megalodon is now the only apex predator in the top of the food chain. Life is good for the megalodon in the warm Pacific.

But the new Pleistocene period brings something that will put an end of more than 20 million years of C. megalodonocean dominance: the severe Quaternary glaciations.

However these glaciation periods are more severe in the northern hemisphere, and each glaciation has a warm interglacial period.

Megalodon's populations are greatly reduced, even in the Pacific. But the monstruous shark is tough, and in 1.5 million years BCE it is still hunting ferociously any prey he can eat.

But his time must come to an end, as all species do.

Reduced to isolated relic populations in the Pacific Ocean, smaller males are fewer, because of cannibalism. The larger megalodon females still try parthenogenesis to avoid the extintion.

But this is not enough.

«Time to live, time to die.»

In Blade Runner movie, Riddley Scott.