To those who don't know what a Megalodon is, below lists the basic information about this animal:
1: It's the largest predatory fish in history measuring at 50-60' long! Some specimens can be even bigger, though all size estimates are from the teeth they leave behind. Fossil records on these sharks begins about 20 million years ago and disappears about 2 million years ago.
2: They resemble more robust versions of Great White Sharks. Assuming you got a MEG tooth the same size as a Great White Shark's, you will notice that the MEG's is 3x thicker! Also, in the world of sharks, the females are bigger and stronger than the males.
3: Fossil evidence shows that they hunted whales, even Sperm Whales! Male Sperm Whales (who are 50-60' long) have no non-human predators today, even Orcas who hunt all other whales don't go after them. Male Sperm Whales are too large, powerful, and aggressive for Orcas (they even sink wooden whaler ships). However, these tough guys were hunted by MEGs!
Okay so the above is a basic info on Megalodons, Paleontologists would agree with the above. Now what is debated is how the disappeared. Below are the basics of MEG extinction theories by the Paleontologists:
Cooling Water Temperatures:
This theory states that, because of the last major ice age that started around 2 million years ago. Now most sharks love tropical to temperate waters, this includes the Megalodon. Without warm waters, especially the nurseries that housed the newborns, was turned too cold for them to survive.
Decline in Food Source:
This other theory states that some whale species died off and the rest migrated to arctic waters. Paleontologists say that the MEGs were coastal predators only, so no whales ment no food for them. This resulted in them dying off as they had nothing to eat but themselves.
Alright so the above theories are the basics for the top theories of MEG extinction. Now I will list my own counter arguments to those theories. Now any of the above and below you can look up to confirm what I'm saying.
Not Coastal Predators Only:
As far as I'm aware of, it was in 2010 that scientists first tracked Great White Sharks diving to the depth that we find the 60' Giant Squids. Since then, we've tracked several specimens diving to these extreme depths. A lot of these areas have no seals, whales (the pygmy kind, Great Whites only eat already dead giant whales), or dolphins in the area yet they are the Great White's food source. However those locations are spots for Giant Squid. Even the Sea of Cortez at Mexico not only has Giant Squids deep down, but also Great Whites (a 19.8' Great White was caught recently in fact) live there. This discovery has dispelled the belief that Great Whites are coastal predators only. If Great Whites are mini, non-robust versions of MEGs and they can go after Giant Squids (though at 60', it's might be younger ones), then why not the MEG? We don't even know the full depth range of Giant Squids, they are still mysterious to us as well as most of the ocean is unexplored. An adult MEG could easily dive deep down (being the same design as a Great White only stronger and bigger built) and dine on Giant Squids if whales were not around.
It's Warmer Deep Down:
Now I'm not saying the ocean got colder or not. We do have evidence that we had an Ice Age back then. Now I'm not sure why we still have Makos and Great Whites today even though they lived in the same time as MEG, but let's say they were not as affected by the cold or lived in areas not as affected... what about the MEGs? Deep in the ocean are hydro-thermal vents, plumes of black smoke who's temperatures can be very high. The Cayman Trench has some of the hottest vents known. Deep sea trenches with these vents create a warm zone, warm enough for a MEG to be comfortable living in. To me it's not a matter of diving capability but how deep. Considering how deep the Great Whites go, a MEG could
go very deep. Several deep sea animals, such as some squids and known deep sea sharks, are deep dwellers that sometimes travel higher up for food. It's not known just how deep Giant Squids live, but I think they too swim up from great depths for food as well. However deep they can live, the MEGs could feast on them while they are at lower levels. Considering that MEGs are cold-blooded (but warm bodied thanks to its and Great White's unique design) they don't need to eat much per day as opposed to a warm-blooded animal.
Sorry for the long counter-arguments, but it was necessary for explaining my point. Diving deep down for food and survival does creates problems for the Paleontologists. Just the Coelacanth was a fish that supposedly died off around the same time as the dinosaurs, yet these 6' fish were found to be still alive just deeper down.
Now I know what some of you are thinking, "Well if it was still alive, wouldn't we see evidence of it?"
. This is a good question, but you must remember my thoughts from earlier. The MEG swam deep down to survive as its old habitat had changed too much for it to survive. Once it swam deep down, and found Giant Squids to feast on, it had no reason to return to the surface. Just the Cayman Trench is 25,217 feet and it's not the deepest trench in the Atlantic Ocean (let alone the whole ocean)! Being that deep down, fish tend to lose color on their skin and become white (cusk eel in the Puerto Rico Trench and Hadal Snailfish are great examples) and the eyes are more adjusted for the total darkness. Remember, any teeth that falls from a shark sinks, it only reaches the beaches if a current can push it towards the beach.
I hope this debate can be an enjoyable one for all, no matter which side you think is right. Ultimately it will take deep sea exploration to determine this once and for all. Fortunately we have the technology to do this, but the ocean is big and will take time to explore. Even if they are not around, I look forward to seeing what does live in the depths of the abyss.
EDIT: Here's a great picture, not by me but a user called SharkeyTrike, of 3 prehistoric Megalodons eating a Sperm Whale http://browse.deviantart.com/?order=5&q=...n#/d4znzxo